Ropemanshdbk3rded Uk

ROPEMAN'S HANDBOOK

Hopeman~

Handbook

Published by the National Coal Board in collaboration with the Health and Safety Executive and The Federation of Wire Rope Manufacturers

Rrst Edition Reprinted Reprinted Reprinted Reprinted Reprinted Second Edition

1952 1954 1955 1956 1960 1961 1966

Reprinted 1971

Third Edition 1980 Reprinted 1985

Preface to Third Edition The ropeman is the person responsible to the colliery management for the examination of winding, haulage, guide and balance ropes, and this handbook is intended to assist him in carrying out his duties. Since the first edition was published in 1952, the handbook has received international recognition as the ropeman's book of reference. In this third edition the text has been updated once again and new illustrations

incorporated.

©Crown copyright.

622.625.505 National Coal Board, Mining Department Ropeman's hSndbook NCB Printed by Simpson Drewett and Co. Ltd., Richmond, Surrey

As in previous editions, the handbook deals with the construction, installation and maintenance of the various types of rope used for mining work. For convenience, winding, haulage, guide and balance ropes are again treated in separate chapters each of which deals with the choi.ce, installation and care of ropes and the common forms of deterioration and damage likely to be experienced. Other chapters give details of rope handling including serving and splicing, rope lubrication, rope examination methods and procedures for fitting various types of cappings or end-fixings. The appendices give a summary of the circumstances under which a rope should be withdrawn from service and some useful information on the tension in ropes on various gradients. An index is also provided to help the ropeman to find the subject ,he requires.

Acknowledgement This third edition of 'Ropeman's Handbook' has been prepared jointly by the National Coal Board, The Health and Safety Executive Research and Laboratory Services Division (previously Safety in Mines Research Establishment), HM Inspectorate of Mines and Quarries and The Federation of Wire Rope Manufacturers of Great Britain. Acknowledgement is made to the many engineers, writers and illustrators who have helped in its compilation.

5

Contents TypesofWire,Strand and Rope

9

2

Rope Handling, Serving and Splicing

26

3

Rope Lubrication

44

4

Methods of Capping Wire Ropes .

52

5

Rope Examination

70

6

Types of Deterioration in Ropes

80

7

Winding Ropes

104

8

Balance Ropes

129

9

Guide and Rubbing Ropes

139

Haulage Ropes

149

10

Appendix 1-Amethod of determining the minimum breaking strength required of a haulage rope

167

Appendix 2-When to discard a rope

169

Bibliography

170

Index . . .

172

7

Chapter 1

Types of wire strand and rope A wire rope consists of many individual wires laid into a number of strands which are, in turn, laid round a centre core (Fig 1). The type and size of wire used, the number of wires in the strands, the type of core and the rope

construction determine the characteristics and strength of a wire rope of any given diameter and hence the uses for which it is suitable.

Figure 1.

Components of a rope

Rope wire

Mild steel as used for structural purposes (for girders, arches, etc) has a tensile strength q.f about45 kilogrammes per square millimetre (28 tons per square inch); ie 1or every square millimetre of its cross-sectional area a piece of mild steel will take a load of about 45 kg (99 lb) before breaking. 9

Ropeman 's handbook

On the other hand, rope steel may have a tensile strength of 180 kgf/mm 2 (115 tonf/in2) or more; ie it can be more than four times as strong as mild steeL The increased strength is obtained mainly by wire-drawing, that is by drawing the wire several times through small tapered holes in metal blocks or dies, the holes being always slightly smaller than the wire to be drawn through them. This treatment steadily decreases the diameter of the wire and increases its length, elongating into fibres the grains of which the steel is composed, and thus increasing the tensile strength of the steel as measured in kgf/mm2 or tonf/in2 (not the breaking strength of the reduced wire as measured in kgf or toni).

Types of wire strand and rope

Wire shapes used in the manufacture of ropes are as follows: -Round - Half-lock - Triangular - Full-lock

Wire manufacture is a very complicated process. Wire-drawing tends to make the steel brittle and heat-treatment is needed from time to time to correct this tendency to brittleness or, in other words, to restore ductility (the ability of the wire to stand up to bending and other forms of wire distortion without breaking abruptly). Also, to produce good rope wire, the manufacturer must start with clean steel of suitable composition and must take care not to introduce any faults at any stage of production. Eventually a wire of the required size and tensile strength, within acceptable tolerances, is produced, which still retains the ductility and other properties necessary in good rope wire. If the wire is to be used in the making of stranded ropes, the tensile strength will normally be 160 grade (160 kgf/mm2 to 189 kgf/mm 2) or 180 grade (180 kgf/mm 2 to 219 kgf/mm 2). Wire in 180 grade is therefore stronger than wire in 160 grade. However, the fatigue strength (ie the resistance to fatigue) of wire of tensile strength up to 110 kgf/mm2 is proportional to the breaking strength. For higher tensile grade steels, the ratio of fatigue strength to breaking strength decreases with increasing breaking strength. Therefore the higher the tensile grade of the wire the more likely it is to suffer fatigue, ie to develop fine cracks which eventually propagate throughout the wire cross-section and cause breakage of the wire (see Chapter 6).

Guide ropes have large wires which have not been much reduced by drawing; they usually lie in the tensile grades 80 or 90 (80/104 or 90/114 kgf/mm 2). Some older rod guide ropes, which were made by spinning six rods around one and are now no longer produced, may be in the tensile grades 50 or 70 (50/74 or 70/94 kgf/mm 2 ). The specification to which round wire rims! conform before being made up into ropes is generally covered by British Standard (BS) No 2763:1968, although large diameter wires and shaped wires, for example those used in half-locked guid<: ropes, are outside the scope of that specification and are covered by the relevant NCB Specification. A complete list of specifications relating to ropes will be found in the Bibliography (p 170). 10

ie circular in cross-section (Fig 2a) ie rail-shaped, with the sides curved to take a round wire on each side (Fig 2b) ie triangular in cross-section, as used for the core wires of

some strands (Fig 2c) ie Z-shaped or shaped like an inclined bull-head rail which will fit snugly against, or lock into, another wire of the same shape (Fig 2d).

(a) Round

(b) Half-lock

(c) Triangular

Figure 2.

(d) Full-lock

Wire shapes

Strands

A strand is formed by laying up or spinning one or more layers of wires around a strand core as shown in Fig 3. The strand core is either a single wire or a built-up-core of a group of wires (Fig 4). The types and shapes of strands are as follows: -

Round Triangular Oval F1at or Ribbon

as as as as

in in in in

Fig 3a and b Fig 3c and d Fig 3e Fig 3f

Apart from the flat (ribbon) strand, which has no core, all other types should have a core which gives good support to the outer wires. Fig 4 shows the types in general use, those shown in 4h and j being known as built-up-cores (BUC). A simple method of describing briefly, but in detail, the construction of a strand is to quote its type (shape) and the number of wires in each layer, starting from the outside. In Fig 3a the strand is 'round 6/1 ';in Fig 3d it is 'triangular 9/12/BUC'; in Fig 3f it is 'flat 6/nil'. 11

ku~man 's

Types of wire strand and rope

handbook

Triangular strands

Round strands

Round strands may be of simple construction with only one layer of wires around the strand core (as in Fig 3a) or of compound construction with more than one layer (as in Fig3b ). In any shape of strand of a given size, the more wires there are the smaller those wires will be and the more flexible will be the strand. However, from the point of view of safety, there is a limit to obtaining flexibility in this way. When the outer wires of a strand are less than 2 mm (0.08 in) in diameter they may be insufficiently sturdy to stand up to the normal degree of wear and corrosion that occur in colliery service. Therefore, for winding and haulage purposes, the so-called 'flexible' type ropes with outer wires of less than 2 mm (0.08 in) diameter (14 swg) should be used only after careful consideration.

Triangular strands (Figs 3c and d) should have strand cores which are tri~ngular in shape as in Figs 4f to j. The solid triangular core (Fig 4f) is sansfactory when small, but when large is rather inflexible and therefore liable to break up in fatigue when subjected to bending round small drums or pulleys. For the larger strands triangular cores composed of several round wires should be used (Figs 4g to j). Oval strands

Oval strands are used mainly as the inner strands of multi-strand ropes. They normally consist of one or two layers of round wires laid up as shown m Fig 3e round an oval core composed of three round wires (Fig 4d) or one fiat ribbon wire (Fig 4e). Flat strands

(e) 9/1 Oval

(c) 7/6 Triangular

(a) 6/1

Round

Flat strands also are used, in general, only in multi-strand ropes. They are normally composed of six or eight wires laid up as shown in Fig 3f and are used mainly in ropes for shaft duties where non-rotating properties, coupled with flexibility, are very important - eg balance ropes and shaft-sinking ropes.

Ropes

Figure 3.

(b) 6/1

(a) 1

(f) 6/nil Flat or ribbon

(d) 9/12/BUC Triangular

(b) 9/9/1 Round

Strand shapes

(c) Die-formed

(d) 3

(e) Ribbon wire

OVAL

ROUND

~

w

(f) to SMRE

(h) Woven

(g) 3

TRIANGULAR

Figure 4.

12

Strand cores

(j) Rolled

A rope of the stranded type is formed by laying up one or more layers of strands around a main core and a rope of the single strand type by laying up only one straight strand containing one or more layers of wires. Both types are descnbed here. The mam core of a stranded rope is designed to support the strands and IS usually a fibre rope (fibre main core or FMC) but it may be a wire strand (wire strand core or WSC) or a small wire rope (independent wire rope core or IWRC). A fibre main core, which may be of natural or synthetic fibres, is flexible and suitable for all conditions except those in which the rope is subjected to severe crushmg (workmg under high load and on very small pulleys and drums, coilmg on top of Itself m numerous layers on a drum, etc). The wire strand core makes the rope more resistant to crushinrr but also makes it less flexible. The independent wire rope core (Fig 5a, right) makes the rope resistant to crushmg without greatly reducing its flexibility. Natural fibre cores are covered by BS 525:1973. This standard and the appropriate NCB SpecificatiOns (see Bibliography) state that jute shall not be used for the cores of winding or haulage ropes; this is because jute is liable to rot and is too soft to give continued support to the strands throughout some three

13

I1

t\.'l .

Types of wire strand and rope

Ropeman 's handbook

years of service. Synthetic fibres such as polypropylene (fibrefilm core or FFC) may be used as a main core. Such cores have several advantages in that they are easier to manufacture, are rot-proof and are more resistant to crushing, so giving better support to the wire strands. Ropes with synthetic fibre cores are being used successfully as haulage ropes. Extreme care should be taken when socketing these ropes with white metal since polypropylene, for example, melts at about 130°C and there is a danger that the part of the core close to the capping could be adversely affected by heat during the capping process. To reduce corrosion and friction between wires, the various specifications for ropes (see Bibliography) state that the wires and any natural fibre core must be thoroughly lubricated during manufacture unless otherwise stated by the purchaser. These specifications also give the different sizes (diameters) of rope available and quote their breaking strengths.

(a) Round strand rope

•

(b) Triangular strand rope

The main types of wire rope are as follows: Round strand, as in Fig 5a; Triangular strand, as in Fig 5b; Multi-strand, as in Fig 5c; Flat rope, as in Fig 5d; Locked coil, as in Fig 5e: Half-locked, as in Fig 51, used only as guide and rubbing ropes; Rod guide rope, as in Fig 5g, now being superseded by the half-locked rope. The first four above are stranded ropes, being composed of several spirally-laid strands; the last three are single-st..and ropes having only one straight strand. The standard method of denoting the construction of a rope is to quote its type, number of strands, number of wires per strand, construction of strand, direction and type of lay and the type of rope core. For example, the rope shown on the right of Fig 5a is 'Round strand, 6x19 (9/9/1) RH Lang's IWRC', meaning 'Round strand rope having six strands, each consisting of nine wires over nine wires over one wire, with an independent wire rope core, laid up in right hand Lang's lay'. The rope on the left of Fig Sb is 'Triangular strand, 6x8 (7/ 6) RH Lang's FMC' meaning 'Triangular strand rope having six strands, each consisting of seven wires over one triangular wire laid up in right hand Lang's lay over a fibre main core'.

-

(d) Flat rope

(e) Locked coil rope

(f) Half-locked guide rope

Round strand ropes SMRE

Round strand rope consists of six ronnd strands laid around a main core, the strands being either of simple construction with only one layer of wires, as in Fig Sa (left), or of compound construction with more than one layer of 14

(a) and {b) each show simple {left) and compound {right} forms of construction.

Figure 5.

Ropes and rope sections

15

Types of wire strand and rope

Ropeman 's handbook

wires, as in Fig Sb (right). Round-strand ropes are uncomplicated in construction and relatively easy to examine in service as about half the length of each outer wire lies on the surface. Depending upon the actual application, round strand rope constructions can range from the comparatively inflexible haulage rope, with strands of six wires over one, to the flexible type with strands of 36 wires. In round strand rope approximately 55 per cent of the cross-section is steel when the main core is of fibre. It will have a tendency to twist (rotate about its own centre-line) when the load changes in value and, therefore, when used as a winding rope, to twist the cage in the shaft. Reference should be made to the section on round strands on page 12for other qualities and possible faults in this type of rope. Round strand ropes are covered by different specificatiOns accordmg to therr intended use (see Bibliography). Triangular strand ropes

Triangular strand ropes have six almost-triangular strands laid around a main core, the strands being either of simple constructiOn, as m Fig Sb. (left), or of compound construction as in Fig Sb (right). As the strands are triangular and have almost flat sides, they fit together more closely than round strands and give a more compact rope in which about 62 per cent of the cross-section is steel (when the main core is of fibre). They are about 10 per cent stronger than round strand ropes of the same size and tensile strength material, they stand up better to wear as they are of more smoothly circular shape, and they resist crushing better as the strands have a greater bearing area. However, they are slightly less flexible (because they are more compact) and a smaller proportion of the totallength of wire in the rope can be examined at the surface. Like the round strand rope the triangular strand rope has a tendency to twist when the load changes in value. Reference should be made to triangular strands on page 13 for further characteristics. Triangular strand ropes for colliery use are covered by the specifications listed in the Bibliography.

the rope manufacturers (see p 73). It is a fairly flexible type of rope, the degree of flexibility depending on the shape of the strands. Multi-strand ropes are suitable for conditions where rope twist must be minimised but where flexibility is required (as for balance ropes beneath the cages). There is no British Standard or NCB Specification for multi-strand ropes for colliery purposes, but BS 302 (see Bibliography) covers these ropes for general engineering purposes. Flat ropes

A fiat rope (Fig Sd) is made up of several small ropes called 'srn.ntls' or 'ropelets' laid side by side. The ropelets are usually composed for four 'reddies' over a fibre core, each reddy being of 6/1 wire construction. The ropelets are stitched together with one or two fiat or slightly twisted stitching strands of soft wire so as to hold the rope together and equalise the load between the separate ropelets. If there is only one stitching strand (single stitching) this emerges from one edge of the rope, encircles a reddy at that edge, re-enters the rope and passes through the rope to the other edge, following a wavy path of W-form. If there are two stitchings (double stitching) the second stitching strand follows a similar wavy path but at a position half a wave behind. The rope in Fig 5d is made up of six rope lets lymg side by side, each laid in the opposite direction to its neighbours in order to make the rope non-rotating, and fiat parts of the double stitching strands may be seen appearing regularly at the two edges of the rope. In Fig 5d (left) it may be seen that each of the six ropelets is composed of four reddies of 6/1 wire construction; the stitching strands are shown as a white line passing through the rope. This type of rope has a high percentage of the wire surface present on the rope exterior so that it is easy to examine, but It IS also more vulnerable to corrosion attack than an equivalent round rope which will have much less of its wire surface area exposed. For this reason and because; being hand-made, they are very expensive, these ropes are now becoming obsolete.

Multi-strand ropes (non-rotating stranded ropes)

locked coil ropes

A multi-strand rope is built up of two or more layers of strands laid around a main core which is either a small fibre rope (fibre main core), as in Fig 5c, or a wire strand core (WSC), or an independent wire rope core (IWRC). Each layer of strands may be composed of round, triangular, oval or fiat strands. The outer layer of strands is always laid in the opposite direction to the inner layer or layers so as to discourage the rope from twisting when the load changes; hence the term 'non-rotating'. This type of rope is not easy to examine visually as only about half the length of the outer wires of one layer of strands can be seen and there may be several layers of mner strands whose wires cannot be seen at all unless the rope is carefully opened up by

Locked coil rope (Fig 5e) consists of one straight strand containing as many wires as are necessary to give the required rope strength. Its main core is a single central wire as would be present in any round strand. To make the rope non-rotating, the outermost layer or 'cover' is always laid in the opposite direction to the next layer (and usually in the opposite direction to all the inner layers or 'core'). The outermost layer is always composed of full-bck wires (Fig 2d); these lock together and give a very smooth circular shape to the rope, thus minimising external wear. The locking action of the full lock wires is designed to reduce the possibility of a broken wire unravelling from the rope and, at the same time, restrict the ingress of

16

17

Types of wire strand and rope

Ropeman 's handbook

moisture to the internal wires. If a broken wire is detected in the outer layer it should be repaired by lifting out the two broken ends for a distance of approximately 500 mm and either annealing and caulking them back into position leaving a small gap between the wire ends or by brazing in a new length of wire. These are skilled operations and best performed by experts from the rope manufacturers. The second layer of wires, laid in the opposite direction to the outer layer, is composed of shaped wires (alternate half-lock and round wires, Fig 2b) to provide a smooth bed for the outer wires and to ensure that they do not break as a result of nicking (cross-cutting between crossing wires). If the manufacturer introduces a second change in direction of lay amongst the inner layers of a large rope, to balance more accurately the tendency to twist, he will probably also introduce another layer of shaped wires at the same place to prevent cross-cutting. However, locked coil ropes should have no more layers of shaped wires than are necessary, for these close fitting wires leave little space for lubricant. Locked coil winding ropes have many advantages: Size for size they are of greater strength than stranded ropes in the same tensile grade. :::J The smooth external surface gives greater resistance to wear by abrasion. :::J They are virtually non-rotating. :::J The elastic and permanent stretch is less than that of stranded ropes. :::J They can operate under higher radial pressures than any other type of rope. It is, however, less flexible than other ropes. To ensure long service it should not be bent sharply but should work on drums and pulleys whose diameters are not less than those shown in Table 7 (p 119). This type of rope is particularly suitable as a winding rope in cases where large loads have to be raised and where rope twist cannot be tolerated. However, it has some disadvantages. :::J

o Only one layer of wires (representing between 18 per cent and 40 per cent of the total length of all wire in the rope, depending upon the rope size and construction) lies on the surface. Therefore, although the outermost surfaces of the wires of the outer layer can be examined throughout their length, the wires of the inner layers cannot be examined visually at all. :::J Locked coil ropes of 38 mm (H in) diameter or more sometimes give trouble by distorting into a wavy or spiral form instead of remaining straight, as discussed later (see Figs 57 and 64). The reason for this is that the larger ropes, being built up of more layers of wires, are more complex than smaller ropes and as such are more readily affected by any 18

deficiency in manufacturing techniques or operating conditions. Modern friction winding installations, designed to raise heavy loads, are of the multi-rope type employing several small locked coil ropes in parallel rather than one large rope. Tills is better for service life and smaller ropes can work on smaller driving sheaves. There is no British Standard for locked coil ropes, but NCB Specification No 186:1970 applies (see Bibliography). · Half-locked ropes (for guide and rubbing ropes}

Half-locked ropes, Fig 51, offer a smooth wearing surface to the cage shoe or rubbing plate and contain very large section wires to give the best possible wear characteristics. Locking action of the outer wires is designed to ensure that any broken wires whi~h may develop are held in position in the rope so as not to interfere with the free running of the cage or skip. They are manufactured in accordance with NCB Specification No 388 from wire in the tensile grades 80 to 90. Round ropes (for guide and rubbing ropes)

Round ropes consist of one straight strand, usually of six round rods (large wires) laid around a single rod (6/1 construction) as in Fig 5g or, sometimes, of nine rods around six around one (9/6/1 construction). In the past these ropes have been used as guide and rubbing ropes but they are now being superseded by the half-)ocked type and are no longer being manufactured. Table 11ists the advantages and disadvantages of most of the rope types. Rope lay Direction and length of lay

In a stranded rope the strands twist around the rope like screw threads. If they twist in the same direction as a right-hand thread then the rope is in right-hand lay, as in Figs 6a, 6c and 7; if they twist in the opposite direction it is in left-hand lay (Figs 6b and d). The individual wires also twist around the strands. If they twist in the same direction as the strands, then the rope is in Lang's lay (Figs 6a, 6b and 7a); if they twist in the opposite direction to that of the strands, then the rope is in ordinary lay* (Figs 6c, 6d and 7b). Therefore, a stranded rope may be in Lang's right-hand lay as in Fig 6a or in one of the other three lays shown in Fig 6. However, a single-strand rope, such as a locked coil rope, can be only in right-hand or left-hand lay according to the direction of lay of the outer wires. Since there are no * Lang's lay is so called because John Lang patented it in 1879. Ordinary lay is so called because that lay was always used in early ropes (and is still used for fibre ropes).

19

Types of wire strand and rope

Ropeman 's handbook

(a) Lang's lay: wires and strands laid in same direction

(b) Ordinary lay: wires and strands laid in opposite directions

Figure 7. (a) Lang's right-hand

(b) Lang's left-hand

(c) Ordinary right-hand

(d) Ordinary left-hand

Figure 6.

Type, direction and length• of lay

strands twisting round the rope, there is no question of Lang's lay or ordinary lay being involved. Which lay is best? It does not usually make any difference whether right-hand or left-hand lay is used (but seep 29) and, if neither is specified, the manufacturer will always supply right-hand lay as standard. However, in a multi-rope friction-winder one half of the set of ropes may be in right-hand lay and the other half in left-hand lay so as to cancel any rope twist effects. In a drum-winding installation the two ropes working on the drum should have the same direction of lay; it is much better that these ropes should twist the conveyances in the same direction so that they remain parallel to one another, than that they should twist them in opposite directions and reduce the clearance, corner to corner. Lang's lay is better than ordinary lay for withstanding wear; in ordinary lay the wires are bent very sharply around the strand on the outside of the rope and, in

20

Identification of lay

consequence, wear is concentrated on a short length of wire and so is likely to be deeper. The best lay for normal colliery purposes is therefore Lang's right-hand lay; other lays should be used only when there is a special reason for doing so. The length of lay (pitch) of a stranded rope is the distance, measured along the rope, between the crown (highest point) of one strand and the next crown of that strand along the rope. In Fig 6 one strand has been coloured white and the distance between the two crowns, representing one rope lay (one length of lay), has been marked. In the case of a single-strand rope, such as a locked coil rope or half-locked guide rope, the length oflayis the distance, measured along the rope in a line parallel to the axis, between a position on one outer wire and a similar position on the same outer wire when it next crosses the line of measurement. Types of lay

Where there are several layers of wire, as in a locked-coil rope or in a strand of compound construction, the wires of one layer usually cross over those of the underlying layer a number of times in each metre of rope length. This helps to bind the rope together but it also causes internal wear.

21

Ropeman 's handbook

Types of wire strand and rope

This internal wear takes the form of short and relatively deep nicks when the two layers are of opposite direction oflayso that the wires cross at a big : angle; it takes the form of long and relatively shallow grooves when the two layers are laid in the same direction so that the wires cross slowly at a small angle. Internal nicking can often be reduced by adopting 'equal lay' in · which the wires of one layer do not cross over those of th~ underlying layer but lie parallel to them (ie the two layers are laid in the same direction and have the same length of lay). In Fig Sa a strand in normal (cross) lay has all but one of its outer wires removed and one of its inner wires coloured black. This has been done to show that the outer wire has a much longer length of lay than the black inner wire (about 2! times as long) and that the outer wire keeps crossing over inner wires. Fig Sb shows a similarly prepared strand in equal lay and it will be seen that, in this, the outer wire has the same length of lay as the black inner wire and does not cross over

disadvantages. The greatest advantage is that the wires are continuously supported by being continuously in contact with other wires, so they are not liable to fail in fatigue due to secondary bending (p 89). Another advantage is that internal wear (nicking between crossing wires) is avoided. However, equal lay is rather less flexible than cross lay because it is more compact (some or all of the wires of one layer lying continuously in the valleys between wires of the underlying layer); for the same reason, there are less spaces left for lubricant.

(a) Seale

Figure 9.

(b) Warrington

Types of equal lay strand construction

Preforming and postforming > t ,,

,l /

~;-

£1, __ }_. :.-.• •. ;:.;,_.,_;;___ :

-~~---=:

(a) Cross lay: inner and outer wires have different lengths of lay (b) Equal lay: inner and outer wires have the same length of lay

Figure 8.

Difference between cross and equal lay

Most types of stranded ropes are either preformed or postformed during manufacture to give the strands and wires the form they will take up in the completed rope: In preformmg, the strands are given the correct spiral form before bemg made up mto a rope. In postforming the wires and strands are _given the reqmred spiral form after the rope has been laid up; this operatiOn, which IS performed by passing the rope through sets of rollers, beds the rope in addition to bending the wires and strands. Both processes produce the same results- a dead rope which does not tend to unravel or to form itself into loops or kinks when it is slack or free of load. Such ropes are less lively and are therefore easier to handle than conventional types but it must not be assumed that they will not twist when loaded. It is only the non-rotating types, such as multi-strand and locked coil ropes, which resist twisting under changes of load.

any inner wires. To obtain equal lay between any two, or more, layers of wires without deforming the rope shape it is necessary to have either the same number of wires in each layer (so that each wire in one layer sits always in the valley between the same two wires of the other underlying layer, as in Fig 9a) or to have different sizes in one layer (so that the larger ones may lie in the valleys and the smaller ones directly on top of wires in the underlying layer as in Fig 9b ). The various types of equal lay are called Seale, filler Seale or Warrin.gton lay, depending on the numbers and sizes Surface finishing (galvanising) of wires in the layers, but it will be simpler if all forms are referred to as There are many forms of surface finish which could be applied to ropes but, equal lay in this handbook. The advantages of equal lay outweigh the at present, the best one for colliery ropes is galvanising (coating of the 22

23

Ropeman 's handbook

Types of wire strand and rope

individual wires with zinc). A colliery rope can be supplied in one of three finishes: - Ungalvanised (or black) - Galvanised, Type A (a heavy coating of zinc) - Galvanised, Type Z (a lighter coating of zinc)

Ta~le 1

Rope characteristics

Rope Type

Advantages

Disadvantages

Round strand

Easy to examine visually

Tendency to twist as load changes

Fairly wide range of flexibility

Rather vulnerable to external wear

Fairly easy to examine visually Stronger than round strand rope of equivalent size and wire tensile strength

Tendency to twist as load changes

Triangular strand

Less flexible than round strand rope

Withstands crushing and external wear better than round strand rope Multi-strand

Non-rotating

Interior cannot be easily examined visually

Fairly flexible Flat

Easy to examine visually

Vulnerable to corrosive attack

Very flexible in one direction only

Very expensive to produce

Non-rotating Locked coil

Non-rotating Resistant to external wear Stronger than other ropes of same size and wire tensile strength Elastic and permanent stretch less than for stranded ropes

BS 2763:1968 (Round steel wire for ropes) gives details of the two forms of galvanising and refers to BS 443:1969 (Zinc coatings). Why should Type Z ever be used when the heavier coating (Type A) is available? There are reasons. For instance, in locked-coil ropes it is unwise to introduce any factor which might encourage looseness of lay and, therefore, rope distortion; a thick coating of soft zinc which could readily be indented or nicked by crossing wires would be such a factor. All ropes to current NCB Specifications, except half-locked guides and locked-coil winding ropes, specify Type Z galvanising. The actual process of applying the zinc to the wire may be carried out by dipping the wire in molten zinc (the hot-dip process) or by electro-plating methods (the electro-galvanising process). At one time the hot-dip process was not altogether satisfactory because the mechanical properties of the wire (strength, ductility, etc) were affected by the heat of the process. Nowadays, however, in all processes the wire is galvanised at an early stage of wire-drawing; consequently the later stages of wire-drawing give the steel the required mechanical properties and, at the same time, form the zinc into a drawn-galvanised coating which adheres better than an undrawn coating. There is, therefore, no need to specify the process, only the finish required, ie ungalvanised, galvanised Type A or galvanised Type Z. Galvaiiised finish should always be specified for ropes which will have to work under conditions which are known to be corrosive. Ungalvanised ropes should preferably be used only where conditions are dry. Galvanised coatings protect the steel partly by acting as a physical barrier between the steel and the corrosive media and partly because they are attacked in preference to the steel. When a galvanised coating has been removed, the steel will be open to attack. It is therefore important to keep galvanised ropes, like ungalvanised ones, well lubricated during storage and service unless there is a good reason why they should not be lubricated (such as the danger of slip of a friction-winding rope on its driving sheave or the slip of haulage clips on a haulage rope working on a steep incline).

Rather inflexible

Interior cannot be examined visually Large sizes sometimes tend to distort

Can operate under higher radial pressures than any other type

24

25

I Rope handling, serving and splicing

Chapter 2 Rope handling, serving and splicing Storage of ropes

A rope may be in store at a mine for more than two years and during this time it is essential to take precautions against external or internal corrosion. A new rope should not be stored in the open on ashes or other corrosive surfaces, with a tarpaulin or plastic sheet merely thrown over it or even enclosing it completely. A rope and its reel must be able to 'breathe', that is, any condensation collecting under the waterproof must be able to escape easily, otherwise the reel is likely to rot and the rope be attacked by corrosion. In one instance, a galvanised rope which had been in store in the open enclosed in plastic sheeting for 31 months was found to be corroded in those parts which had contacted the reel flanges. The reel was a wooden one and moisture collecting under the plastic sheet had caused bacteria to

However, it is much better if reels or coils of new rope can be stored away from the weather and any fumes in a dry, cool, well-ventilated building out of th~ path of the sun's ra~s and under conditions where the temperature remams as steady as possible and does not rise much above the normal value of 16°C. A steady temperature avoids condensation: a temperature which does not rise much above 16°C prevents the lubricantfrom becomino thin and running out of the rope. At 21°C most lubricants are twice as fluid as at 16°C: at 27°C they are about three times as fluid. The coil or reel should stand on timbers rather than on a concrete floor and if stored vertically, should be rotated from time to time to prevent d;ainage of lubricant to the bottom. Any place where ropes are stored should be kept free of rodents since rats and mice would be attracted to the rope lubricant; their droppings could set up corrosion in the ropes. If the rope remains in store for a considerable time it should be inspected at interval~ and fresh lubricant applied as necessary. If the ropes are to be used on fnction-wmders, any re-lubricating should be discussed with the Colliery Engineer.

Uncoiling and unreeling of ropes

Rope reels and coils should always be handled with care. Never drop a reel or coil from a lorry or truck when unloading but put a suitable bar through the central hole of the reel a~d hft it with suitable slings and lifting tackle. Never lift a coil of rope by its securing bands but always pass the sling throngh the central hole in the coil. Coils and reels of rope may be unwound by one of the following methods:

o A light coil of rope may be unrolled along the ground like a hoop as in Figure 10.

Protective hood for rope in store

attack the wood, forming acids which then attacked the rope. If wooden reels are to be used, then Baltic redwood is the best timber as it takes preservatives well and is not so prone to attack. If ropes must be stored in the open, the best arrangement is to use a hood, as shown in Fig 10, consisting of corrugated steel sheeting fastened to a timber frame which rests on top of the reel flanges. This keeps off the rain, grit, etc but allows air to circulate all round the reel. 26

Fig lla. Make sure that the floor is clean and that all the remaining rope is held together so that no tight coils or kinks occur. Rope should never be pulled from a statiOnary coil as in Fig. llc. o A coil or small reel of rope may be laid on a turntable (Figs llb and 12a) and the free end of rope pulled off as the turntable revolves. 0 A bar may be passed through the centre hole of a reel and mounted on a stand (Fig 12a) so that the reel rotates as the rope is pulled off. If loops should form they must be taken out by carefully rolling them to the free end of the rope, otherwise kinks will form. The rate of rotation of large reels should be controlled by some simple form of braking. This may be either a plank held agamst the reel flange as in Fig 12b or an adjustable fnctlon drum on the shaft or side plate as in Fig 12c. 27

Ropeman's handbook

Rope handling, serving and splicing

Correct coiling of stranded ropes on drums If a stranded rope is fitted incorrectly to a smooth-surfaced drum it may coil badly, forming open or widely spaced coils instead of closely packed coils, The correct way to fit a rope to such a drum in order to encourage close coiling in the first layer of coils is given below. (b) Right: using a turntable

(a) Right: rolling the coil along the ground

When looking at the drum in a direction towards the shaft or haulage plane: o A rigbt-hand lay underlap rope should have its dead end at the right-hand flange of the drum. o A rigbt-hand lay overlap rope should have its dead end at the left-hand flange of the drum. It has already been mentioned (p 20) that both ropes in a shaft should have the same direction of lay, normaiiy right-hand lay. The above method of fitting the ropes may be remembered by the foiiowing means:

(c) Wrong: pulling the rope from a non-rotating coil

Figure 11.

Right and wrong methods of uncoiling a rope

When looking at the drum in a direction towards the shaft or haulage plane: o Extend your rigbt hand (for right-hand lay) towards the under side of the drum (for the under rope), with the palm towards the drum (ie upwards) and with the index finger pointing towards the shaft or haulage plane. The thumb will then be near to the right-hand flange of the drum where the dead end of the underlap rope should be (Fig 13a).

(a) Taking a rope from a small reel

(a) Underlap rope Cb) Braking with a plank against the reel flange

Figure 12.

28

(c) Braking with an adjustable friction drum on the shaft or side plate

Correct methods of unreeling a rope

(b) Overlap rope

Use ofindexfinger of right hand to deoidecorreot method

Figure 13.

Starting a right-hand lay rope on the drum

29

Rope handling, serving and splicing

Ropeman's handbook

o Extend your right hand (for right-hand lay) towards the top side of the drum (for the over rope), again with the palm towards the drum (ie downwards) and again with the index finger pointing towards the shaft or haulage plane. The thumb will then be nearest the left-hand flange of the drum where the dead end of the overlap rope should be (Fig 13b). In the unlikely event of the ropes being of left-hand lay, the left hand should be use.d instead of the right. It will then be found that a left-hand lay underlap rope should have its dead end at the left-hand flange, and an overlap rope at the right-hand flange.

In the case of a haulage rope which coils badly in the first or subsequent layers on the drum because of flapping of the incoming rope in front of the drum, the solution may be to mount a pulley freely on a long shaft extending across the full width of the front of the drum. As the rope runs in this pulley the flapping will be damped by the pulley which, however, can ' move slowly along its long shaft to feed the oncoming rope onto the correct part of the drum. Except on bicylindroconical (BCC) drums the direction of coiling is not ' as important for locked coil ropes as it is for stranded ropes. ·

Serving a rope

A serving (sometimes referred to as a 'seizing') is a wrapping of wire laid· tightly around a rope to prevent its wires from 'kicking' or moving to slacken themselves when the rope is cut between two adjacent servings. A serving is not sufficient unless it prevents all kicking or movement of the wires. The colliery ropeman should know how to serve a rope efficiently. It is no use wrapping a few turns of wire, string or insulating tape around the rope in the form of open or partly-overlapping coils. That is not serving. The correct size and type of serving wire must be applied to the rope tightly, under proper tension and in neatly-laid parallel coils which are in hard contact with one another (otherwise they could move sideways and become slack). Only single wire should be used as a strand of fine wires might collapse or flatten in places and, consequently, become slack. The serving wire must be of soft material so that it will readily take a permanent bend and accommodate itself to the shape of the rope. If it did not, the rope would kick and accommodate itself to the shape of the serving. Thus, a good serving on a six-strand rope will appear somewhat six-sided. To sum up, the serving must be applied by means of a serving mallet to keep it under proper tension and get it tight; the wire used should be tinned annealed mild steel serving wire or soft iron serving wire; it should be single wire, not a strand; and it should be of the correct size for the rope. 30

Size of serving wire

Serving wire which is very thin is too weak and fragile; one that is very thick is too rigid and unlikely to accommodate itself to the shape of the rope. Only three sizes of serving wire are needed to cover the full range of rope sizes. These are given in the following table: Table 2

Sizes of tinned annealed mild steel or soft iron serving wire for ropes of various sizes

Rope diameter mm(in)

m

Size of single serving wire mm (in)

Standard wire gauge SWG

1.32 (0.052)

17

22 to 38 (t- H)

1.57 (0.062)

16

Larger than 38 (H)

1.83 (0.072)

15

Less than 22

Length of serving

The length of rope to be served depends on the object of the serving and on the size and type of the rope. If the serving is to restrain the cut end of a rope it must be longer than one intended to restrain the end of a short sample to be cut from a rope. A rope of the stranded type exerts only a moderate bursting force on a serving but a large locked coil rope exerts a considerable bursting force and, should the serving burst, the rope will unlay itself violently over a long length. Thus, for the cut end of a stranded rope, two servings each of a length at least six times the rope diameter should be used and kept in place until the rope end is otherwise secured. For the cut end of a large locked coil rope a serving or servings each a length of twenty times the rope diameter is advisable, and such servings should be backed up by a minimum of six two-bolt clamps set clear of the served length until the rope end is otherwise secured. Servings should be left permanently on locked coil winding ropes so that there is one about 0.6 m (2ft) clear of the cape! to allow proper examination of the rope at this point and another between the cape! and the nearest pulley or driving sheave in the headframe. This is to localise any unlaying of the rope end, or of broken wires, in the event of some incident. Serving tools

The tools essential for serving are as follows: o A vice or other means of holding the rope. o Serving mallets, such as the types shown in Fig 14a for stranded ropes, 31

Ropeman 's handbook

Rope handling, serving and splicing

and Fig 15a for locked coil ropes. The heads of the mallets should be shaped to enable them to sit on the rope and should be of brass or other soft material, which will not score the rope. The handles of the type shown in Fig 14a should be long enough to take a reel of wire. o A reel capable of being mounted on_the handles of the mallets shown in Fig 14a and on which sufficient wire can be wound to complete a serving. o Pliers and wire-cutters, for twisting wire ends together and cutting them short. o A small soft-headed hammer, for tapping the coils of a serving into contact with one another. D A heavy soldering iron, made from a copper block approximately 76 mm x38 mm with one long face ground flat, for completing a soldered or wiped serving.

(b)

Serving operations

A new ropeman must acquire his skill in serving under the instruction of an experienced man_ There are two types of serving, as follows: The ordinary or buried-wire serving is usually confined to stranded ropes : and to parts of the rope which have not to he fitted into sockets or other · confined spaces. The basic idea is to lay the first part of the serving wire ! along the length of rope to be served, and then to wind the wire tightly over ' it in coils so that the two ends of the serving wire finish at the same place where they can be twisted together and cut off short to complete the 1 serving. ~

Firstly, in making such a serving, the free end of the serving wire on the reel is paid out for about 0.5 m (18 in) and its extreme end is clamped in the vice together with the rope (Fig 14b). This paid-out wire is then led from the 'ice along the rope to the far end of the rope length to be seized (in a stranded rope, after the first few turns of the serving have secured it, the wire would be laid in a valley between two strands and would, therefore, spiral around the rope)- This part of the wire is the buried wire_ The paid-out wire is then bent to lie at right-angles to the rope and is given a couple of turns around the rope, so as to lie on top of the buried wire and form the beginning of the serving (Fig 14b). The serving mallet is then placed on the rope, on top of these two turns (Fig 14c). Then the wire leading from these turns is passed over the top edge of the mallet and round the back of the handle (Fig 14c)_ The process is continued by passing the wire over the top edge of the mallet again, under the rope, up over the other edge of the mallet and the reel placed on the handle of the serving mallet (Fig 14d), the reel being turned to take up the slack wire. 32

, / r

· !

i

SMRE

· : i

. ·

(a) Serving mallets and reel of wire. (b) Rope and end of wire clamped in vice and wire wound between strands to star: of serving. (c) Two turns of wire mede around rope and serving mallet placed 1-n position. (d) Wire brought over edge of mallet. around handle and back over mallet edge, then under rope and over opposite edge of mallet. Reel then placed on handle. (e) Serving begun keeping wire taut. ':fl Serving finished and ends of wire twisted together with pliers.

Figure 14.

One method of serving a stranded rope

33

Rope handling, serving and splicing

Rope man's handbook

As the mallet is rotated round the rope in a direction to continue the serving (Fig 14e) the drag or friction of the wire passing round the mallet handle will ensure that the serving is applied tightly to the rope, under proper tension. The ropeman must control the turning of the reel on the handle so as to pay out wire only at the rate at which it is needed; slack wire will mean slack serving. As he lays more and more coils or turns of serving on the rope he must keep those turns tight and keep them in hard contact with one another. If the wire tends to form open coils not in contact with one another he must tap the coils into place with his soft-headed hammer before he proceeds further, so as to pack the coils closely together. A method of guiding the wire into close packed coils is to cut a guide-groove for the wire in the head of the mallet, as shown in Fig 14a. When the length of serving is completed, the wire from the final coil and that from the buried wire are twisted together, pulled tight, twisted further to keep them tight and cut off so as to leave about four twists remaining in the twisted end (Fig 14f). This short twisted end is then knocked down with the hammer so as to lie neatly against the rope. In the case of a stranded rope the expenenced man will arrange that the twist is so situated that it•can be knocked down into a valley between two strands.

,. . .· ;

i

! i·

\ j.

~

1

j

I The soldered or wiped serving is the best type of serving. It is suitable for locked coil ropes and for parts of rope which are to be threaded through sockets. The Idea IS to serve directly on to the rope, Without any buned wire being present, so that the two ends of the serving wire lie at opposite ends of the serving. No attempt is made to twist or join these ends of wire. The type of serving mallet used is shown in Fig 15a and the steps in the process for serving right-hand lay rope in Figs 15a to 15d.

~­ ,

~ ~

1:

[ !

Using the recommended size of tinned annealed mild steel wire, the ! starting end of the wire should be reeved from the bobbin on the serving I mallet and made fast to a nearby object or lashed to the rope with yarn or : tape. This fastened end should be to the ropeman's left hand. The serving mallet is then passed around the rope until the wire holds it in position where the cut is to be made. The serving proper is now started by raising the handle of the mallet upwards and towards the body, passing it over the rope and down away from the body, moving to the right (Fig. 15a). When the serving has reached a length of about 150 mm (6 in) its surface should be thoroughly cleaned, in preparation for soldering (Fig 15b). On this cleaned surface a liberal quantity of Coraline flux (or powdered rosin) , should be spread (Fig 15c). Baker's fluid or killed spirit should never be ' used as a flux because they could penetrate between the turns of the serving : and severely corrode the rope. The coils of wire should now be soldered :· together along one side of the rope using the heavy soldering iron and [ tinman's solder. The hot iron should be passed to and fro across the surface : 34

Figure 15.

Method of applying soldered serving to a locked coil rope (British Ropes Ltd)

of the serving so that the solder flows into the interstices between the turns of servingwir~ (Fig 15d). The sequence of serving and soldering is repeated until the requrred length (20 times the rope diameter) of serving has been completed. Splicing of haulage ropes

Splicing cannot be learnt from a book alone; a new rope man must acquire ~IS skill un~er the tmtmn of an experienced splicer. A description of the long splice as used for JOmmghaulage ropes end to end, or for inserting a new l~ngth of rope mto an endless haulage rope, is given below. The 'short splice_, as used for formmg an eye or loop on the end of a rope, will not be desmbed as 1t IS not employed in colliery practice in this country. It is llllportant, of course, to ensure that any rope spliced into another is of similar size and construction, and of reasonably similar length of lay. 35

Ropeman 's handbook

Rope handling, serving and splicing

The long splice

If the splice joining two ropes (Rope A and Rope B) were made over a very short length, the rope would be definitely weakened and distorted at that place. However, haulage ropes usually have six strands and, consequently, a much neater and stronger splice can be obtained by spacing the 'joints' of the six strands at well-separated intervals along the rope. In Figs 16b and c, Strand NolA (of Rope A) is replaced by Strand No 1B (of Rope B) at a joint situated well away from the joint at which Strand No 2A will be replaced by Strand No 2B, and so on until all the six strands of Rope A have been replaced by strands of Rope B. This is the principle on which the long splice is based. Fig 16d shows the resulting six joints, with the ends of their strands crossed and ready for tucking into the rope. (The joints are shown much closer together than they should be, in order to fit them into the illustration.) Each joint is completed by arranging that the strand of Rope A and its opposite number of Rope B meet and pass one another for a distance equal to the selected tucking length (Fig 17a). Then this tucking length of each strand is tucked or buried in the heart of the rope, in place of an equal length of the main core which is cut out (Fig 17b). The minimum length of each strand which must be tucked in order to give a secure joint, and therefore the minimum length of the whole splice, depends on the size and length of lay of the rope and also on the conditions under which the rope works.'The Engineer will advise on these lengths. The minimum length of the whole splice is twelve times the tucked length of each strand in the case where no main core is left between tucks. A tucked length for each strand of 75d (d=rope diameter) has been found reliable for all but the most exceptional conditions. The following table for the values of the length of tuck and length of splice is based on that value.

Table 3

9-13 14-19 21-26 29-32 35-38 41-44 48-51 51-54

36

(c)

;:,;:~::::;;~~~~

Lengths of tucks and splices

Rope diameter

mm

Rope B

in

Length of tuck

.

i-~ ~

16-4

~ -1

H-H H-H H-H H-2 2 -2!

Length of splice

m

in

m

ft

1 1.5 2 2.5 3 3.5 4 4.5

40 60 80 100 120 140 160 180

12 18 24 30 36 42 48

40 60 80 100 120 140 160 180

54

SMRE

(a) Ropes served at half the length of the intended splice and strands

splayed out. (b) Ropes brought tightly together. strands paired, serving

removed and strand 1 A unwound from rop~ A for full length of splice. (c) Space left by strand 1 A is filled by strand 1 8 from rope B and short lengths of each are left for tucking. (d) Six pairs of strands treated similarly.

Figure 16.

Making a long splice

37

Ropeman 's handbook

Rope handling, serving and splicing

There are several varieties of the long splice and several orders in which the operations may be carried out. These are best learnt from an experienced splicer. The following description is given merely to show the general principles of one type: o Serve each rope (Rope A and Rope B) atadistancefromits end equal to half the length of the splice. Put a short serving or whipping of string on the free end of each strand. Separate the strands of both ropes as far back as the main serving and cut away the two free pieces of main core (Fig 16a). o Marry the two rope ends so that the strands of Rope A lie regularly and in order between the strands of Rope B (Fig 16b). o Divide the strands into pairs, each pair consisting of one strand from Rope A and its adjoining strand from Rope B. Tie the two strands together where they cross, if that will help to keep them in their pairs. In Fig 16 Strand lA (from Rope A) and Strand 1B (from Rope B) form a pair; Strands 2A and 2B form another pair; and so on. o Pull the two ropes hard together by some means, fix them in that position, and remove the two servings (Fig 16b). o Take one pair of strands, say lA and lB. Run lA out of its rope and lay 1B in its place until the whole length of lB, except the length to be tucked, has been used up (Fig 16c). Cut lA so that only the length to be tucked remains, as on the extreme left of Fig 16c. Tuck these two ends (as explained later), or tie them in place ready for tucking. o Do the same with the next pair of strands, but in the opposite direction along the rope. That is, run 2B out of its rope and lay 2A in its place, leaving only the tucking lengths free as before. o Run the third pair in the same direction as the first pair, but only for three-fifths of the distance. That is, run 3A out of its rope and replace it by 3B for three-fifths of the length from the marrying point to the joint where lA and lB are tucked or ready for tucking. Cut 3A and 3B so as to leave free only their tucking lengths. o Do the same with the next pair, 4A and 4B, but in the opposite direction. (It is usual to run successive pairs of strands in opposite directions but some forms of splicing do otherwise.) That is, run 4B out and replace it by 4A for three-fifths of the length from the marrying point to the joint where 2A and 2B are tucked or ready for tucking. Cut the ends so as to · leave only the tucking lengths free. o Run SA out of its rope and replace it by 5B over a length equal to one-fifth of the length from the marrying point to the joint where lA and lB are tucked or ready for tucking. Trim the ends to leave only the tucking lengths free. o Run the last pair in the opposite direction. That is, run out 6B and replace it by 6A for one-fifth of the length from the marrying point to the 38

joint where 2A and 2B are tucked or ready for tucking. Trim the ends to leave only the tucking lengths free. There should uow be six pairs of strand ends tucked or ready for tucking, that is to say, six joints spaced equally along the splice as m Fig 16d. (For ease of illustration the joints are shown much too close together.) In that illustration the joints are shown in the order: l, 3, 5, 6, 4, 2, readmg from left to right.

) 1 i

1 1 1 '

!.· ,

1

In other varieties of the long splice the order of the joints may be different; for instance the order: 1, 3, 5, 2, 4, 6 may be considered better because it keeps the joints in neighbouring strands further away from each ?!her. As already stated, the actual form of splice and the order of operation~ to be adopted in a particular case is best decided by an expenenced splicer. Tucking

When a strand is to be tucked, the pull on the rope should be slackened off enough to allow for the insertion between the strands of a tuckmg tool, spike or needle. If the rope is of round-strand constructiOn, the whole of the tucking length (Fig 17a) of each strand should be wrapped with twmeor tape, from the extreme end up to a pointabout 25 mm_ (1m) from the J~mt to make it at leastthe same size as the mam core that It Is to replace. (This IS to ensure that the tucked length will be securely held inside the rope.) If the rope is of flattened strand construction, its strands will already be larg~r than its main core and the wrappmg will not be necessary. However, m this Strand A

Strand 8

(a)

Strand A

Strclhd 8

Core

SMRE

Tucked ends

Figure 17.

Tucking strand ends into a rope

39

Rope handliag, serving and splicing

Rope man's handbook

case, the extreme end of each tucking length should be served or whipped with fine string or tape to prevent it collapsing. If the rope is of the preformed type (p 23) the tucking lengths should be straightened before being tucked. An experienced splicer is best fitted to give detailed instruction on tucking, but the general method of tucking a pair of strands is as follows: o Fix the rope in a vice (or by some other means) so that the joint of the two strands to be tucked is just clear of the vice or fixing. o Insert into the rope the spike, needle or tucking tool at the point where the two strands cross, pull out the main core and cut it through. o Rotate the spike around the rope with the lay (iemove italongtherope, while still in the rope, rotating it around the rope m the same direction as the rope lay). Move it in a direction away from the joint or crossing point of the two strands and, at the same time, keep pulling out the main core and replacing it by the strand to be tucked until the whole length of that strand is tucked. Cut the main core so that the end of the core remammg in the rope abuts hard against the end of the tucked strand and no part of the rope is left hollow. (A hollow rope will collapse or distort.) o Move the vice or alternative fixing along the rope so that the second strand of the pair can be tucked. o Before running in this second strand, get the crossing point of the tw_o strands to fit snugly into the rope with the aid of hammer blows on aprur of splicing tongs or swage. Run in the second strand as m the third Item above. o Smooth out the shape of the rope over the tucked lengths, using hammer blows on tongs or swage, or by hammering the rope itself between two wooden mallets which will not damage the wires. The two tucked strands should now-lie within the rope as shown in the diagram in Fig 17b. o Tuck the other pairs of strands in the same way and smooth out the shape of the rope over the whole splice. Tucking is the most skilled part of splicing. The most important thin~ in tucking is to get the rope back to its proper shape and as nearly as possible to its original diameter at the point where the two tucked strands enter the rope. If parts of the tucked strands (or any strands) protrude from the rope or 'stand proud' at this point, they will rapidly become worn through during service. It usually happens that the two tucked strands do he neatly in the rope but that the two neighbouring strands (under which the tucked strands ar~ first tucked) stand proud and become heavily worn. fig 18 1 shows such a case where the two tucked strands have escaped wear, but the strands on each side of the joint have become severely damaged by wear. Care must be taken to tuck the ends of the tucked strands well into the ' rope. If this is not done, as was the case with theropeinFig19, theendmay catch on some obstruction and be torn out of the rope. This happened m

40

I :1

Figure 18.

' .!

Rope worn at a faulty tuck

SMRE

Figure 19.

Protruding end to tucked strand

one instance when a protruding strand end caught in a rail slot. The tucked strand was torn out of the rope until the tuck cross-over point was reached when a holdfast occurred and the rope eventually broke. "There are two main types of tuck: - the parallel, or flat, or side-by-side tuck; - the crossed, or round, or locked tuck. The side-by-side tuck (Fig 20a) is probably the easiest to make and is quite satisfactory. In fact tucks of either type seldom pull out if they are of sufficient length and are well made; the most common trouble with long splices is localised wear, as in Fig 18. In the side-by-side tuck the two strands to be tucked enter the rope without first crossing one another, so that they lie parallel or side-by-side at the joint as in Fig 20a and present a somewhat flat appearance. In the crossed tuck th two strands cross one another or are locked before entering the rope, as in Fig20b, and present a more round appearance.

41

Rope handling, serving and splicing

Ropeman 's handbook

(a) On the right incorrect method of repair, whereby

I

I

the rope is reduced to five strands instead of six at point of repair

Defective strand

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...... , ...................... <·:·:·>:"{

.;.:-::-:,::::* <=:=· ...... , ..,,.,.,.,,,,,,:,:;,,:

,,,,.,•••••••••••••. ,, .• , •.•••.•.••.J.·· Point o,f repa"ir

..

Replacement strand

Defective strand

I

I

=~: ·······.····.··.·.··.·=~:::~··········;:: ~:=

(a) Side-by-side tuck

•••

••••••

·····················.·:·:·:·:·<=:<=~·;:,:•:w.••

SMRE

••••••••••••·•••••••.•••.••.•.••.•••.•·.•.••.w.··;·>:

• •• • •• •••••

·,·,;.. ;.:ow.<'.·

···:·>"•:•:•: ··:·:·:·:·>:;:·

(b) Correct method of repair

Figure 21. Method of replacing a defective strand in a six-straiid rope

(b) Locked or crossed tuck Figure 20.

Types of tuck used in splicing

It is difficult to get a rope back to shape, and to its original diameter, at a

joint because at some point in the joint two strands are attemptmg to occupy the space intended for only one. However, a good splicer can grve instruction on the many ingenious ways of restoring the rope to its proper shape. One device is to slightly untwist the two strands to be tucked, over a length of 25 mm (1 in) or so at the part where they he together m passmg one another. As a result this part of each strand is made soft and spongy and capable of being re-shaped by the pressure of the tongs or swage; also, in the case of a crossed tuck, the loosened outer wires of the two strands mesh together to some extent. If a strand stands proud in a joint and becomes worn through as in Fig 18, it will unravel from the rope and may cause an accident. Thus, the ropeman is sometimes faced with the need to make a speedy repair during a shift. One fairly common practice (or malpractice) is to trim the broken ends of the strand and to tuck them into the rope, so that theydonotpassoneanother 42

before entering the rope, as in the diagram in Fig 21a. This leaves the rope with only five useful'strands, for the tucked strand has no strength at its cut ends. Many ropes have broken at such five-stranded parts. In tucking, the two strands must always pass one another before being tucked into the rope; otherwise they cannot hand over their load to one another. Even in an emergency repair the rope must have six strands on the outside. The correct procedure in making such a repair is to cut out several yards of the defective strand and to insert a somewhat longer length of similar strand in its place as a replacement strand, tucking all four ends so that their ends pass before being tucked as shown in the diagraminFig21b (where the two joints are shown much too close together in order to fit them in the diagram). Thus, the main points to remember in connection with splicing are:

o Get the tucked strands and their neighbours at the jointto fit snugly into the rope so that no strand stands proud, otherwise that strand will rapidly wear through in service. o If a strand does become worn through, or broken from any cause, cut out several yards of the defective strand and replace that length by a similar strand. The tucks at the end of the replacing strand should be so made that the strands pass one another before being tucked (Fig 2lb). 43

I: Chapter 3

Rope lubrication

majority of lubricants now used for this fall into two main classes: - petroleum-based compounds, - bitumen in mineral oil compounds,

with a predominance of the petroleum-based type. Chemicals are added to the basic lubricant to improve the performance. These additives include anti-corrosion, anti-oxidation, water-repellent, anti-fret agents, etc. Except in certain cases, the lubricant is applied during all stages of manufacture. It is sometimes applied cold but more generally heated, according to its viscosity, to obtain the optimuin condition for application.

Rope lubrication

The purpose of wire rope lubrication is two-fold. Firstly, it facilitates freedom of movement between wires within the rope, thus reducmg friction and internal wear and improving the distnbutwn of load. Secondly it protects both internal and external surfaces of the wires from corrosion'. External lubricant reduces friction and exte:r;nal wear between the rope and any drum or pulley over which It passes; It can also help to reduce internal wear by restricting penetration of dirtand gnt which could

The completed rope may be passed through a final bath of lubricant. For locked coil friction-winding ropes, specially developed bitumen-based lubricants may be used. General practice is to heavily lubricate the inner layers of the rope with a bitumen-in-oil compound, laying up the outer one or two layers in a virtually dry condition. In service the lubricant spreads to the outer layers but should still be contained within the rope, thus avoiding contamination of the sheave linings and, hence, rope slip. Lubricants (batching fluids) are necessary during the spinning of natural fibre cores to prevent the fibres from breaking. To avoid internal corrosion of the rope, these lubricants must be free from acids and water. The core fibres themselves must be free from acids and salt and should contain only the combined water necessary to prevent brittleness. BS 525:1973 gives the requirements for such cores. Before incorporation into a rope, a fibre core may be impregnated with further lubricant.

otherwise cause increased abrasion. In certain conditions, however, too

liberal use of too sticky an external lubricant will attract grit and so reduce rope life. The essential properties of a wire rope lubricant are: it must be tough enough to resist abrasion but sufficiently plastic to remain intact as the rope flexes in service; . . 0 it must adhere firmly to the wires and b~ VIscous enough to resist gravitational forces (ega winding rope hangmg vertically m a shaft) and centrifugal forces (ega rope working on a high speed wmder); 0 it must, itself, be non-corrosive, stable over the range of temperatures and environmental conditions (eg salt water) likely to be encountered and under no circumstances give rise to any by-products which would attack the metal strands; 0 it must be water-repellent to protect internal and external surfaces from corrosion; h b 0 it must not deteriorate with age, exposure or temperature c anges, eg Y hardening or cracking; and . . .. a lubricant (dressing) applied externally durmg serVIce should, additiOn0 ally, have good penetration to compensate, as far as possible, for any loss of the manufacturer's internal lubncant. It must also be fully compatible with the lubricant used in manufacture.

0

Lubrication during service If a rope is to remain in good condition it is important to re-lubricate it at 1!. ·

I

[ Lubrication of ropes during manufacture

II

Because it is difficult to lubricate fully the internal part of a rope once it is made up, ropes are thoroughly lubricated at the manufacturmg stage. The

1

44

f

intervals during service. The oil or grease (dressing) used should be one specially designed or approved for ropes and should be free from all harmful substances such as acids. It should be of mineral origin rather than animal or vegetable origin, for the latter tend to break down eventually and produce acids. The rope manufacturers and oil companies will advise on suitable lubricants, including the additives to improve the properties. The kind of dressing used and the frequency of application varies with the type of rope and its usage, but there. are certain general principles to be followed. These are: o Whenever practical the dressing should be applied as soon as the rope is put to work. o The dressing should be re-applied at regular intervals, normally before the rope is showing signs of corrosion or dryness.

45

Rope lubrication

Ropeman 's handbook

Advice should be sought from oil suppliers and rope manufacturers as to the most suitable lubricant, bearing in mind that the lubricant must be compatible with the lubricant used in rope manufacture.

o Periodically, it is important to clean existing lubricant from the rope before relubricating, particularly in dirty or dusty conditions (eg skip winding shafts). o If loose corrosion products are present on the rope surface these should also be removed before fresh dressing is applied. o The dressing and method of application should be such that a thin, even, adherent coating covers all the wires in the rope.

The atmospheric temperature and weather conditions may affect the viscosity of the oil, particularly where long pipe runs are exposed. Protection of the pipes and keeping the temperature of the oil reasonably constant in the small reservoir are advisable.

Drum-winder ropes

Drum-winder ropes should be re-lubricated at regular intervals; this should be at least once a week for busy ropes in wet shafts. For such arduous conditions, lubricants are available containing additives having anti-corrosion, tackiness, water-repellent and, in some cases, de-watering properties. The de-watering additives in bitumen-based dressings emulsify with the water present on the rope and ensure that oil is kept in close contact with the surfaces of the wires. It is necessary to clean this type of dressing from the rope before it becomes saturated with water. The right time to clean andre-lubricate the rope can be judged from the colour of the dressing which changes as its water content increases. With petroleumbased compounds containing de-watering additives water is removed from the rope but it is not absorbed by the compound to. the same extent as by bitumen-based compffounds.hWThinding rohpeds hmayhbe cldeanetd andfregrebased manually, using a sti brus . IS met o as t e a van age o ena 1mg the rope exterior to be examined at the same time but it is a rather long and laborious one. Other methods are available and are described below. Automatic lubrication of winding ropes can be achieved by pumping lubricating oil from a small reservoir positioned either in the winding engine house or at the headgear pulley level (the pump being motorised or driven by either the winding engine or the headgear pulley shaft). The oil is distributed by smaU flexible pipes to the point of application onto the rope as in Fig 22; bending of the rope round the pulley then assists penetration and distribution of the lubricant. The quantity of oil dripped onto the rope is usually determined by experience. Care must be taken to ensure that control of the supply is keJ?t under close supervisi9n as excess oil on the rope may result m contamination of the winding drum brake path and linings, the headgear and the engine house. Experience has shown that automatic lubrication, carefully controlled, results in the ropes being uniformly lubricated and the quantity of oil applied is usually Jess than that used by manual methods. It is important, when using the drip feed method, that the rope lengths between the cape] and the headgear pulley and between the headgear pulley and the drum are oiled manually.

46

!

Oil feed to be applied preferably to descending rope

!.·

I

I 1.

Headgear pulley

Figure 22.

Automatic rope lubrication

It is also important to remember that the ropes still require cleaning at

intervals to free them from dirt, grit, etc. One method of cleaning ropes is shown in Fig 23. A method for cleaning locked coil ropes, which also serves as a broken outer wire detector, is to use a short length of high tensile steel wire in the manner shown in Fig 24. A type of pressure lubricator has been developed which is particularly suitable for the internal lubrication of locked coil ropes. It consists of a gland which is easily clamped to a stationary rope and, when working at 2 kg/mm 2 (3000 lb/in2), is said to be capable of Jubricating9-12m (30-40ft)

47

Rope lubrication

Ropeman 's handbook

l~:I

I

\f

of rope on each side of any one clamping position. With this device, particular lengths likely to suffer deterioration (such as the acceleration zone) may be treated effectively without lubricating the whole rope. It is also useful in arresting waviness (see p 99) in a locked coil rope, particularly when this is due to insufficient freedom of movement between the rope wires. Before this type of lubricator is used the rope manufacturer should be consulted. Friction-winder ropes

Figure 23.

Typical wire brush rope cleaner (British Ropes Ltd)

In the case of friction-winder ropes externally applied lubricants or dressings must not seriously reduce the coefficient of friction between the rope and the driving sheave. When friction winding was first introduced, these ropes were not lubricated in service but now specially developed dressings for friction-winder ropes are available and have proved quite successfuL The dressings can be applied by hand at, say, monthly intervals, but very great care must be taken not to over-lubricate; the dressings should be used sparingly and any surplus should be wiped off with a cloth. Too much lubricant could cause rope slip directly or could result in the build up of deposits which could eventually cause either rope slip or uneven rope travel (and hence unequal tensions in the ropes). If the Engineer agrees, it is often a good idea to clean andre-lubricate one rope at a time on multi-rope friction-winders, say, one per week or one per night. Despite the precautions taken during manufacture, newly-installed ropes sometimes exude excess lubricant. Consequently, new ropes should be frequently and carefully examined during the initial operating period. Similar precautions need to be taken if a rope has been recently pressure lubricated. If excess lubricant is found it should be removed with a cloth, moistened, if necessary, with a little transformer oil to help to dissolve the lubricant, and finally wiped dry with a clean cloth.

The nse of harmful drying agents such as gritty dusts should be avoided although, as a last resort in very extreme cases, cement dust has been found successful in absorbing excess lubricant. Such methods must only be used on the authority of the mine Engineer. Balance ropes

Wooden handle

Figure 24.

48

Looped wire method of cleaning and examining locked-coil winding ropes

Balance ropes, whether galvanised or not, should be kept well lubricated for they often work in corrosive conditions. Oeaning is just as important as lubricating for, if the lubricant cannot reach the rope surface, it does no good whatsoever. A lubricant of the type used for guide ropes may be nsed but in many cases, especially for flat balance ropes, a thinner dressing 49

!lj.. '

':il

Rope man's handbook

Rope lubrication

applied by spray gives better results. This method offers bette: penetration, keeps the ropes cleaner and enables the ropes to be exammed more easily. Guide ropes

A commonly used type of dressing which gives good results in dry oro?IY slightly wet co11ditions is a viscous, bitumen-based compound contammg anti-rust tackiness water repellent and de-watenng addJI1ves. In wet shafts, d~essings with adhesive and emulsifying properties generally give better results. Under the most severe conditions, where large amounts of corrosive Water are present, dressings with anti-rust and dew~tering properties but containing no emulsifying agents are often used. Th1s type of!ubricant is difficult to apply, since the surface of the gmde rope must first be thoroughly dried, but it lasts for a reasonable time before a fresh application is needed.

Lubricating after capping

When a rope is capped or recapped with a white metal socket, it is possible for some of the internal lubricant to be lost from the part of the rope adjacent to the cape!. This loss could encourage corrosion and fatigue of the wires at this critical part. After completion of the capping process, therefore, the rope close to the mouth of the cape! should be thoroughly regreased. For fibre-cored ropes, a patented system is also available whereby a lubrication tube, fitted with a grease nipple, is cast into the white metal having been previously pushed down the wire brush and its end inserted into the fibre core. When the completed capping is cold, lubricant is pumped in to replace any which may have melted out. The process can be repeated as necessary during the life of the rope.

Haulage ropes

Haulage ropes, whether galvanised or not, should be kept well lubricated. The same care should be given to the smaller, occasionally used haulage ropes as to the busy man-riding ropes; it is often on these small installations that the more serious accidents occur. Haulage ropes suffer mamly from wear and corrosion and the dressings most suited to combat these are either very viscous oils or soft greases which contain tackiness additives together with either molybdenum disulphide orgraphite. Other dressmgs which may be used with success are heavy residual oils and b1tummous compounds. A mechanical lubricator suitable for man-riding haulage ropes where the rope is horizontal is shown m Fig 25. As the rope IS drawn slowly through, the pulley transfers lubricant from the bath onto the rope, the wiper removing excess lubricant, distributing the remainder and working it into the rope.

Pulley adjustable for height

Figure 25.

50

Lubricator for haulage ropes

51

[

Metlwds of capping wire ropes

Chapter 4

- Axis of pin

j '

Methods of capping wire ropes

Old capping

'

'

Molten metal poured

Fibre core (if any) removed

Completed

capping

6d discard

- ,,_1_

X---

~---X-

C

il!

:::

Rope centring clamp

.... -tl

@ ~

-~

•

_§ c

T

I

Capping with molten white metal White metal is an excellent medium for capping, is widely used, and works on the principle of gripping the wires individually in a single cone of white metal within a conical socket. When properly made and in BS or NCB standard sockets, this type of capping is as strong as the rope. The correct procedure for making this type of capping was determined by a team of NCB, HM Inspectorate, rope manufacturers and SMRE staff; to ensure that a reliable capping is obtained it should be strictly observed. The progressive operations for capping are illustrated in Figs 26-28 and detailed below.

x•~

AT

A new ropeman cannot become expert in capping merely by reading a book on the subject; he must acquire his skill and experience under the tuition of a man already skilled in the wrrk. However, a book can help both of them and act as a reminder of the various steps that have to be taken and the correct order_ It must be remembered that efficient serving is important in all types of capping. The three types of capping which will be described here are as follows: - white metal cappings; - wedge-type cappings; - cappings with inserted cones and tails. Note: After· completion of capping or recapping of a windi-ng or haulage rope, a trial run with the &flpel subjected to normal load should be carried out, followed by an examination of the capping, before the rope is returned to service.

.

Bolts in marker clamp oriented same as pin in new

capping 3.6m

{12ft)

Rope

I

diameter

l

(d)

fgo

I~

oN

SMRE

:

'r ,J_

(a)

(b)

(c)

(d)

(e)

(f)

Serving and clamping

In order to prevent any loosening of the wires during the cutting and capping operations, the rope must be securely served before cutting off the old capping or excess length of new rope and, where appropriate, clamped on both sides of the proposed cutting point X in Fig 26a. Tinned annealed serving wire of the size shown in Table 2 (p. 31) should be used. On no account should copper wire be used as it is iiable to cause corrosion.

52

(a) Serving and clamping. (b) Cuning. (c) Unserving and cleaning of brush. (d) Preparation of brush for socket. (e) Positioning the socket and pouring. (f) Completed capping; clamps and servings removed.

Figure 26.

Progressive operations for capping with molten white metal

53

Methods of capping wire ropes

Ropeman 's handbook

For stranded ropes apply two or more short servings at least 6d in length (d=rope diameter) to secure the rope end; the servings may be of the soldered type or of the type where the ends of the serving wire are finally twisted together to complete the serving. In the case of locked coil ropes, more stringent precautions are necessary. With these ropes, the serving AB (Fig 26a) on the part of the rope to be discarded should be at least 6d in length. On the part to be retained, the serving CD should have an overall length of not less than 20d plus the length of the socket basket. A further length of serving, 20d in length, should be applied lower down the rope about 3.6 m (12ft) from the first serving. Then, as an extra safeguard, six clamps should be fitted between these two lengths of serving (D toE in Fig26a). Each served length must be of the soldered type but need not necessarily be composed of one continuous length of wire. When applying the serving wire, the serving mallet should be rotated in the direction that will tend to flatten the locked wires into the rope rather than in the opposite direction which would tend to raise their leading edges.

(a) Opening out the brush

(b) Cleaning the brush

The six clamps should be of the half-clamp, two-bolt type with a machined bore and having a 3 mm (kin) gap between the half clamps when tightened on the rope. The clamps should be set on the rope alternately at right angles to one another, the clamp nearest the old capping being used as a marker clamp, if required, with the bolts in the required direction of the pin in the new socket. Before cutting the rope, set temporary clamps at Band C immediately on either side of the cutting point X.

(c) Wire twitch applied to brush

(d) Pulling the socket into place

Cutting

Cut the rope at X by any suitable method which does not disturb the wires. With percussive or shearing methods special care is required to avoid any disturbance to the serving or to the wires in the rope. After cutting the rope, remove the temporary clamp at C and thread the new socket (to NCB Specification 465/1965 for a winding rope) over the end of the rope, pushing it along the serving as far as the marker clamp. (Before threading the socket onto the rope, make sure that the inside of the socket basket is clean and dry and that there are no rough places on the radiused position at the socket mouth.) Apply another clamp over the serving at F so that the length XF (Fig 26b) is equal to the length of the basket less about 2d. The value of about 2d is recommended so that sufficient length of served rope will be inserted into the mouth of the socket to ensure that the point at which the wires begin to separate to form the 54

(e) Rope centring clamp

Figure 27.

Preparing a rope for capping with molten white metal (British Ropes Ltd)

55

Rope man's handbook

brush will be well embedded in white metal, rather than being in hard contact with the small end of the conical bore of the socket. Opening up and cleaning the brush

Remove that part of the long serving between X and F. With large locked-coil ropes care should be taken with this operation, as the rope wires will tend to open with some force, and a clamp at F is essential to ensure that the rope does not loosen beyond this point. Open the rope over the length XF. Separate all the wires (Fig 27a) but do not straighten them, and take great care to avoid bending or twisting any wire too sharply at F (Fig 26), otherwise deformed wires may break in fatigue during service. If there is a fibre core it must be cut at F and removed. To ensure secure grip of the white metal on the wires, thoroughly clean each wire of all traces of lubricant or dirt with a water-soluble degreasing fluid or a non-flammable organic solvent. Paraffin is not recommended. During this operation keep the brush in a downward position (Fig 27b) to make sure no de greasing fluid enters the unopened part of the rope as this may affect its internal lubricant. The brush should remain in a downward position until all the wires are completely dry. Preparing the brush

By means of a single turn of serving wire placed around the brush near its top end (Fig 27c) or, in the case of a large rope, two or three single or double-turn servings spaced along the length of the brush where required, draw the cleaned wires of the brush slightly together, but only sufficiently to prevent appreciable lengths of the outermost wires from bearing against the wall of the socket when the socket is pulled onto the brush. This will ensure that the wires are effectively embedded in the white metal. Positioning the socket and pouring the white metal

The temporary clamp at F (Fig 26) can now be removed and the socket pulled onto the brush so that the ends of the wires are approximately 5 mm above the top of the socket basket at S; this leaves a length of about 2d of the serving at F contained within the mouth of the socket. Before the socket is pulled into position it sho'uld be rotated on the rope until orientated similarly to the marker clamp at D. It can then be drawn carefully over the prepared brush by any means which provides a direct axial pull. Fig 27d shows a suitable method. The drawing operation should finish when the wire ends still protrude approximately 5 mm above the top of the socket basket so that any movement of the wires relative to the white metal may be noted, but care must be taken that the wire ends will not foul

56

Methods of capping wire ropes'

the mating unit which will be subsequently connected to the pin of the socket. A special rope-centring clamp should now be fitted to align the socket accurately with the rope (Fig 27e). This clamp should also provide for an annular space at the base of the socket which is filled with white metal during the pouring operation and incorporates a drain hole which acts as a

tell-tale during pouring to indicate that the required penetration has occurred.

w :j'

The rope end should now be carefully positioned vertically. It is essential that the rope should be exactly vertical for a distance of at least 36 times the rope diameter directly below the socket. It is helpful if the rope can be clamped to a kingpost known to be truly vertical, otherwise check the verticality carefully with a plumb bob. Whichever method is used, also check with a spirit level to make sure that the socket is exactly level. If a rope and its socket are not exactly aligned, bending stresses will be produced in the rope at the mouth of the socket; these could induce premature fatigue failure of the wires in this region. In order to prevent chilling of the metal during pouring, the socket should now be pre-heated to the correct temperature (see Table 4) by fitting a suitable furnace around it, or by means of constantly moving blowtorches or other suitable heating nozzles (Fig 28a). Oxy-acetylene flame cutters must not be used for heating the socket. Table 4

I

.I

i

Pre-heating temperatures for sockets

Material of socket

Pre-heating temperature

Mild steel 1.5% Manganese steel and other approved steels to BS 2772 Part 2:1977

If manganese or other approved steel sockets are heated to the upper end of the temperature range, better penetration of the white metal will be obtained. When heating nozzles are used care must be taken to apply the heat evenly to all parts of the socket to reach the required temperature. Under no circumstances must flame be allowed to play on any part of the rope. The socket temperature can be readily checked by applying suitable thermocrayons or a contact type pyrometer to various parts of the socket.

Whilst the pre-heating operation is being carried out on the socket, the white metal (to BS 643:19'70 or NCB Specification 483/1970) should be 57

:i !

;·i

i

i

I.'

Rope man's handbook

Methods of capping wire ropes

The wires within the socket should be treated with a non-acid flux or finely powdered rosin, which must be dusted among all the wires within the heated socket immediately before pouring the white metal. After bringing the molten metal to a temperature slightly in excess of the pouring temperature and immediately before pouring, stir the molten metal thoroughly right to the bottom of the pot and skim off all dross from the surface. Ensure that the stirring implement is clean and dry. It is helpful if the pot has a vertical baffle close to the pouring lip and extending to within 25 mm of the bottom. This allows only clean metal to be poured.

(a) Heating the socket

(b) Pouring the white metal

When the metal is at the correct pouring temperature (as determined by a suitable thermometer) pour the metal into the socket in a continuous stream until it reaches the top of the basket (Fig 28b). The pouring should be done slightly off-centre to allow venting and gas escape. At the start of the operation white metal should run from the tell-tale hole in the centring clamp (Fig 28b). The metal should be allowed to run for two or three seconds before the hole is plugged by a third person using a suitable stopper. If a depression or 'pipe' occurs in the centre of the white metal during the early stages of cooling it should be topped up with a small amount of white metal. When the basket is full, the socket should be left to cool naturally and undisturbed for at least one hour.

Dismantling the clamps and servings

(c) Neck of completed capping

Figure 28.

Final stages in capping with molten white metal (British Ropes Ltd)

prepared and heated to the correct \'ouring temperature of 350oC±l4'C .• (660°F ±25oF). A predetermmed weight of white metal m excess of that ; required to fill the socket should be broken up, placed m a clean pot ~d •· heated in a furnace until molten; flame should not be allowed to play on! e ; metal itself. New ingots of metal must be used for wmdmg rope cappmos. 58

After the completed socket has cooled, the rope-centring clamp and two-bolt clamps should be removed and the socket neck examined to make sure that penetration of the white metal has occurred round the whole of the rope circumference. A further check can be carried out to ensure that the cape! has been completely filled with white metal. If the remaining metal in the pot after pouring, together with any spillage, is weighed, the weight of the metal in the cape! can be determined. The socket should be allowed to cool to air temperature before use. If sufficient time for natural cooling is not available a stream of cold air may be directed onto the socket to increase the rate of cooling, but this should only be done after the white metal has completely solidified. In no circumstances should the socket be immersed in water for cooling. The long serving is then removed up to the point where it enters the mouth of the socket. This is to facilitate subsequent examinations of the rope near the socket mouth. It is useful to paint a well-defined mark about 12 mm wide on the rope just below the socket (Fig28c). This serves to indicate any broken wire which might occur at the socket neck, as movement of an individual wire is immediately seen.

59

Ropeman 's handbook

Methods of capping wire ropes

When the capping has reached air temperature the length of rope next to the socket must be re-lubricated. The capping is then ready for use. Possible faults in procedure

The white metal used must be of the correct composition (to BS 643:1970 and NCB Specification 483/1970) and heated to the correct temperature (350°C±14°) otherwise it may fail to penetrate to the narrow end of the conical part of the socket and, therefore, to the narrow end of the brush of separated wires. On the other hand, the temperature of the white metal should not exceed that specified otherwise the heat may adversely affect the wires of the brush. An open socket (one with two lugs rather than a bowed end) facilitates the pouring of the white metal. The socket must be of the correct size; for winding ropes it must conform to NCB Specification 465/1965. If the socket is too short, the length of each wire embedded in the white metal will be insufficient to ensure that the wire is securely gripped at loads up to its breaking strength; a length of embedded wire equal to about 40 times its diameter will ensure proper grip and leave a margin for safety, provided that the wire has been properly cleaned. On the other hand, the socket must not be too long otherwise the taper of the conical part will not be steep enough or wide enough to allow the molten white metal to reach the narrow end of the socket before solidifying; the taper should be 1 in 7 or steeper (1 in 6 is steeper than 1 in 7). If the wires at the narrow end of the socket are loose and unsupported, they will bend and twist with every movement of the rope and they will very likely break in fatigue. Figs 29a and b show cappings where this occurred. In Fig 29a the socket, with an insufficiently steep taper of 1 in 12, has been cut open in the laboratory to show that the white metal did not penetrate to the narrow end of the socket and that the wires at that part failed in fatigue. It is to ensure that the wires at the narrow end of the brush are properly embedded in white metal that the procedure stipulates that the narrow end of the brush should not lie right at the narrow end of the conical part of the socket but should lie further inside at a wider part of the socket. When fitting sockets to NCB Specification 465/1965 a length of about twice the rope diameter of seized rope should lie within the socket mouth.

The socket must be pre-heated uniformly and to the correct temperature. Inadequate heating could result in lack of penetration of the white metal; over-heating could adversely affect the material of the socket or of the rope wires. Careful cleaning of the wires throughout the brush is essential, otherwise they will not be gripped properly by the white metal. Fig 29c shows the 60

(a) Half section of a socket showing imperfect penetration of white metal and rope breakage

(b)

(c) Fractured outer wires

Imperfect penetration of white metal and fractured wires Figure 29.

Faulty white metal cappings

socket end of a locked coil rope which had not been cleaned properly during capping. The outer wires were without lubricant and were securely . gripped by the white metal but the inner wires were very greasy and, consequently, were not properly gripped. The result was that the outer wires carried nearly the whole load - much more than their share; they were, therefore, loaded well beyond their fatigue limit (p 88) and finally failed at the mouth of the socket. 61

Ropeman 's handbook

Methods of capping wire ropes .

Recovery of socket

Fitting the safety block

The white metal cone should be removed from the socket by pressing out. Should this prove difficult the socket may be warmed·, provided that the critical temperature for preheating, given in Table 4, is not exceeded. Examination of the extracted cone will provide useful information on the quality of socketing procedures.

Thread the safety block, which should be clean and dry and free from rough places at its mouth, over the rope end so that the larger end of the conical bore is towards the rope end. Now fit a temporary clamp over the serving so that its top edge is th<( length of the safety block less one-half the rope diameter from the rope end and remove the serving wire at the rope end down to the top of this clamp. The procedure is now similar to that for making a white metal capping. That is,

Wedge cappings

Wedge cappings work on the principle of gripping the unopened rope between interlocking tapered wedges (with grooves to suit the rope diameter) enclosed in limbs encircled by heavy bands. After initial bedding down, the rope should not move in the wedges and, because of their interlocking action, the wedges cannot move indepensJently of each other. The wedges and the rope must, however, be able to move as a unit, so that,

if the load on the cape! is sufficient to cause movement of this unit, the force on the wedges will be increased and consequently the greater will be the grip exerted upon the rope. A safety block is fitted to act as a rope movement indicator and to assist movement of the wedges should this become necessary. The cape! can be used with stranded or locked coil ropes. These instructions show its assembly on a locked coil rope; they apply equally to assembly on a stranded rope. Capel wedges are stamped with the rope type and size for which they are grooved and also with the cape! identification number. Wedges should be fitted only to a cape! having the same identification number. Check that all component parts, ie limbs, bands and wedges, bear the same cape! number. Capels should NEVER be used with a size or type of rope different from that stamped upon the wedges. The number of bands will vary with the design and manufacturers of the cape!. Under no circumstances should liners be used in the grooves or atthe backs of the wedges. Serving and clamping

The rope must be securely served and clamped on both sides of the proposed cutting position in the same way as for white metal cappings (see p 52); the length CD (Fig 26a) for locked coil ropes should be equal to 20 rope diameters + the length of the safety block. Cutting

Cut the rope in the same way as for white metal cappings (p 54). 62

o Separate the wires at the rope end to form a small brush, cutting out the fibre core, if present, close to the serving and avoiding undue bending of the wires over the edge of the clamp (Fig 30a). 0 Thoroughly clean an· the wires in the brush with a water-soluble degreasing fluid, keeping the brush in a downward position so that no degreasing fluid enters the unopened part of the rope. Remove the temporary clamp close to the brush. o Pull the safety block into position over the rope brush so that a length of serving equal to one half the rope diameter is projecting into the bore of the block. The wire ends should be flush with the top of the block. o Camp the rope, with the safety block in place, in a vertical position with the large end of the block uppermost, taking care that the rope is in axial line with the block for a distance of not less than 36 rope diameters. The bottom of the safety block should be sealed with a tight serving of asbestos yarn on the rope to prevent the escape of molten white metal.

o Heat the outside of the block with a blowtorch, gradually and evenly all round the outer faces (see p 57). Avoid undue local heating and particularly avoid heating the rope outside the block. Monitor the temperature of the block with thermal crayons and when it has reached a uniform temperature in accordance with Table 4 (p 57) fill the block with molten, clean white metal, poured at a temperature of 350°C±14°C (660°F ±2SOF). Heating of the block is essential to the free flow of molten metal; undue heating may impair the strength of the rope wires.

o The white metal used should have been previously melted from new ingots of the composition laid down in NCB Specification 483/1970 and in BS 643:1970. The pouring pot should be of sufficient capacity to hold the full amount of white metal to fill the bore of the safety block. The pot should have a minimum capacity level mark for the quantity of molten white metal required for the block and should incorporate a baffle plate to ensure that only clean, bright fluid metal is poured into the prepared, heated safety block. The temperature of the white metal should be obtained immediately before pouring using a suitable thermometer. .63

Ropeman 's handbook

Methods of capping wire ropes

When the safety block is at the correct temperature and immediately before pouring the white metal a non-acid flux or finely powdered rosin should be dusted among the wires in the core of the block. Pouring should be continuous, uniform and slightly off-centre until the white metal completely fills the block, and when the surface of the white metal sinks in the centre, a little more should be poured in from the pot (as with white metal capping). o Leave the rope and block undisturbed and allow it to cool gradually until the white metal has set and the block has reached air temperature. o Remove the asbestos yarn and the serving from below the safety block and check that the white metal has fully penetrated the block. o Check the length of rope to be gripped by the wedges for uniformity of diameter and compliance with the cape! rope groove tolerances. Fitting the cape!

Prior to assembly, remove any protective paint, grease or backing strips from cape! limbs and wedges. Remove any traces of rust which may have accumulated on the\vedge backs and grooves, and also on the inside of the limbs over the area on which the wedges operate. Emery cloth only should be used for this purpose. Remove any burrs or damage on wedges and limb section ~ particularly the area over which the wedges operate ~ which may have occurred in handling, storage or transit. (If left they may interfere with the movement of the wedges.) Assembly may now be carried out in the following order.

{a)

o Thread the cape! bands onto the rope in order of their numbers (usually the largest number first, but always the band of smallest aperture first). Make sure that the taper of the inside of the bands accords with the outside taper of the cape! limbs. This is often shown by arrows stamped on each of the bands and on the limbs; these must all point in the same direction (Fig 30b ). o Thoroughly clean any grease and lubricant from that portion of the rope which will be gripped by the wedges and ensure that the rope is straight, clean and dry. o Clean the BACKS of the wedges and the inner sides of the cape! limbs. Then apply a light smearing of grease to the BACKS (NoT THE GROOVES) of the wedges and the inside of the limbs. Note: Only greases recommended by the cape! manufacturer should be used. Do NOT use tallow, graphite grease or grease containing molybdenum disu!phide. THE GROOVES OF THE WEDGES MUST BE CLEAN AND

(b)

(e)

{c)

{d)

{f)

DRY.

o Place the wedges around the rope approximately in the position they will occupy when in the cape!.

64

Figure 30.

Stages in assembling a wedge-type winding rope capel

65

Ropeman 's handbook

Methods of capping wire ropes

'1.'I,1,

ill

o Fit the cape! limbs over the wedges and draw downwards until the ends of the limbs are flush with the thin end of the wedges. The rope should then be drawn through the wedges until the safety block is 20 mm (!in) from the bottom of the wedges (Fig 30c). o Draw the bands over and tap them down on the cape! limbs. The No 1 band should be fitted adjacent to and encircling the safety block (Fig 30d). o Using purpose-made sets, which should fit snugly on the edges of the bands adjacent to the cape! limbs, each working band (starting with No 2) should be partially tightened. This procedure should be repeated until all the bands are finally driven down tight and solid (Fig 30e ). The suggested weights of hammers to be used for driving on the bands are: -for capels to suit ropes up to 38 mm (H in) in diameter, 3 kg (7 Jb) 5.5 kg (12 Jb) - for capels to suit ropes between 38 mm (H in) and 48 mm (H in) in diameter and 6.5 kg (14 lb) - for capels to suit ropes above 48 mm (1,\ in) in diameter. Two strikers should be employed to facilitate uniform tightening. The sides of the bands adjacent to the wedges should never be struck as otherwise burrs can be caused which may foul the wedges and hinder their movement. Band No 1 is intended only as a protection for the safety block and need not be driven on to a very tight fit. The 'working' bands (Nos 2, 3 and 4 in the illustration) when properly driven on, should be spaced about equally along the cape! limbs, the top ('point') band being slightly short of the end of the cape! (Fig 30!). An alternative method of tightening the bands on the cape! limbs is to use a hydraulic banding machine (Fig 31) and press the bands tight with suitable pressure. The cape! manufacturers will advise on the correct values to use for the different sizes of cape!. Precaution -

Under no circumstances should a capeI be fitted to a rope without the white metal safety block.

If slack rope should occur in a winding rope fitted with wedge-type cappings, care must be taken when the rope is being re-loaded. The cape! bands must not foul obstructions otherwise they could be pushed off the cape! limbs.

Capping haulage ropes with inserted cones and tails Cone and tail socketing is a simple field method of attaching sockets to six-strand ropes. It eliminates the need for socketing by white metal, where heating methods are not available. 66

:ii

·~

Figure 31. Hydraulic banding machine for assembling wedge-type winding rope capels (by courtesy of Reliance Rope Attachment Co Ltd)

The d~vice consists of a tail or length of steel wire strand, on one end of which IS cast a zinc cone. This is grooved so that the six strands of the rope are positioned and equally spaced around the cone. The cone is shaped so that it fits snugly into the interior of either an open or closed socket to the NCB Specification 353/1966 or 461/1965. Method of fitting The preparatory stage (Fig 32a) shows the rope end, the socket and the cone and tail unit. Only the correct size of socket and a new cone and tail unit should be used. Both are stamped with the rope diameter for which they are designed. The tail of the unit should not be shortened. ~bread the socket onto the rope. Remove the serving from the rope end and unlay three neighbouring strands for a length of approximately75 mm more than the length of the cone and tail unit. Measure off from the rope end the length of the cone and tail unit plus 10 mm. Remove the rope core down to this position and cut it (Fig 32b).

Insert the tail strand in place of the removed core and relay the unlaid strands to reform the rope. Place the strands one in each of the grooves proVI~ed on the cone, takmg care to follow the n,aturallay of the rope and ensunng that the strands protrude over the end of the cone (Fig 32c). 67

Ropeman 's handbook

Methods of capping wire ropes

Bind the rope tightly at the small end of the cone using fine wire of a size which will allow the rope to pass through the small end of the socket. This binding is to prevent unlaying of the rope end (Fig 32d).

Three strands

(b)

Three strands

Three strands··

Now draw the socket into position by applying a load equal, if possible, to the working load. After this assembly load has been applied, or preferably while that load is still on, a tight binding of soft iron single wire (not strand) must be placed on the rope close up to and touching the mouth of the socket (Fig 32f). This is to prevent the socket moving on the rope. This binding should be equal to H rope diameters and the wire used must be of a size sufficient to prevent the socket passing over it. The starting end of this binding should be anchored under one strand of the rope. The assembly is then complete. This method of assembly is used for the open socket and for the closed type socket, shown in Figs 32f and 32g respectively. After the socketing has been completed, a trial run should be made and followed by an examination of the termination, especially the coarse binding at the small end of the socket. Should this binding cease to meet the socket after a period of service, then it should be replaced as above.

(c)

Three strands laid up tightly round tail

(d)

(f)

(g)

Figure 32.

68

Progressive operati-ons for capping with inserted zinc cone-and-tail units

69

Rope examination

Chapter 5

Rope examination

(a) Micrometer

(b) Eyeglass

Ropeman's tools and instruments

The ropeman needs a number of tools and instruments to enable him to maintain and examine all types of rope efficiently. The tools needed for serving or splicing a rope have already been described (Chapter 2) and the following additional items would also be useful. Wire micrometer

(c) Scriber

This is a screw-operated instrument for measuring the diameter of a wire, or the remaining depth of a worn or corroded wire. A micrometer with two pointed measuring ends (Fig 33a), or with at least one pointed end, is suitable (the pointed end can be placed in a large corrosion pit to measure the depth of the pit or the remaining depth of the wire).

I---

90 mm

---1

1.--E._j~

Ropeman's magnifying eyeglass

'i.

A watchmaker's eyeglass with a magnification of two or three is suitable, for it can be held in the eye so as to leave the hands free (Fig 33b).

·I

Sturdy penknife

320mm

:

This has many uses, such as scraping corrosion scale from wires, inserting between adjacent outer wires to check if they are loose and can be prised

:i

apart, etc. !,

Scriber, for corrosion pits

A strong needle-pointed instrument is useful for exploring the size and depth of scale-filled corrosion pits. A scriber With a replaceable needle point such as. the type shown in Fig. 33c is particularly suitable. (d) Calipers

Rope caliper

This is a parallel jaw caliper, as shown in Fig 33d, used for measuring the diameter of the rope.

70

(el Hammer

{f) Trammel

SMRE

Figure 33.

Ropeman's tools and instruments

71

Ropeman's handbook Rope examination

Ropeman's hammer

This is for testing looseness of wires; it is a light hammer with a head having

one end fiat and the other end chisel-shaped as shown m Frg33e. It can be purchased as carpenter's pinning hammer. Rope lay trammel

This is for measuring the length of lay of ropes. The measurement will be very inaccurate if the measuring scale of the trammel rs not kept truly Jlarallel to the centre-line of the rope whrle the measurement IS bemg made. A self-aligning trammel is, therefore, useful. The type shown m Fig 33f has two V-notched end-pieces, whrch rest on the rope and ahgn the trammel correctly. To assist in keeping the rope strmght when measuring the lay, a grooved lay board is useful. Set of feeler gauges

Incorrect (above) Jaws parallel to four strands

These are. for determining the width of gaps between strands and between or under individual wires.

Detailed rope examination A skilled ropernan is able to make enlightened examinations, knowing as he does the various forms of deterioration (see chapter 6) that may affect the rope and the signs or symptoms by which he can recognise them. He can also· make reliable and informative reports such as wrll ensure that the rope is properly maintained and that it can be taken out of servrce before rt reaches a dangerous condition. General external appearance

The examiner should note if there is any evidence of distortion, waviness, displaced or broken wires, corrosion or damage (as distinct from deterioration). He should note the amount of lubncant present on the outside of the rope and whether it is of useful consrstency or has become dry and useless. He should record his findings in a book or on a smtable form. Measurement of diameter and lay length

Wherever the rope diameter and lay length are to be measured, the outside of the rope should be cleaned thoroughly. At each posrtron of measurement the rope diameter should be measured wrth calipers (Frg 33d) in two directions at right angles to one another, the length of lay measured with a self-aligning trammel (Fig 33f) and the results recorded. 72

Correct (right) Jaws on crowns of opposing strands

Figure 34. Method of measuring rope diameter

When measuring rope diameters, the calipers should be placed across the crowns of two opposite strands as in Fig 34 (right). When measuring rope lays, the measuring scale or trammel must be truly parallel to the centre-line of the rope otherwise the reading will be very inaccurate. If a rope sample is being examined at a Testing Centre and if ·the sample should be slightly curved, a lay board can be usefuL This is a board with a straight groove, of a size to take the rope, into which the sample can be pressed to hold it straight whilst its length of lay is measured. Detailed examination of exterior

The examiner should look in more detail for wear, corrosion, broken or cracked wires, surface embrittlement, etc. He should note if the wear is heavy or otherwise, if it is of a plastic nature (seep 80) or if martensitic cracking (seep 96) is present on thewom crowns. If corrosion is present he should note its severity and whether it shows any signs of penetrating between the wires and strands. He should also consider if better lubrication is needed. With stranded ropes, if internal corrosion is suspected the Engineer may decide to call in the rope manufacturers who will be able to open up the rope carefully over short lengths and visually examine the state of the core and the undersides of the strands. 73

Rope examination

Rope man's handbook

The examiner should also look for looseness of wires by carrying out the hammer test. This consists of tapping the rope or sample at intervals with the flat end of the head of a ropeman's hammer (Fig 33e). If there is any looseness of the outer wires he will both hear and feel it chatter when he taps the wires, for only the unsupported wires which he taps will vibrate, not the whole rope. If there is a large amount of corrosion product (rust mixed with dried lubricant) inside the rope he will obtain a muffled sound and feel a soft reaction through the hammer. If the rope is well laid up, with all the wires in hard contact with one another, he will obtain a ringing metallic sound and a solid feel. Detailed examination of interior

When short rope samples are being examined (eg recapping samples), after the three examinations described above have been carried out the sample should be stripped. In the case of stranded ropes the strands should be removed from the sample and the condition of the main core checked for lubrication, etc. The part of each strand which has been next to the fibre core should be examined for lubrication and corrosion and the part which has been in contact with other strands for nicking and corrosion. The outer wires should then be removed from two or three strands and the interior of the strand examined for lubrication, internal wear, internal corrosion, etc. The position of any deterioration should be noted. Fig 35 helps in identifying the different parts of a wire and strand. When stripping a locked coil rope, care should be taken to avoid springing of the wires. The following method is recommended. Secure the sample in a vice that is firmly attached to a stout bench and lift the end of the first turn of serving at one end of the rope. With a pair of pliers, remove two or three turns of serving and wind the wire onto a short piece of wood. Then, standing facing the end of the sample so that when the wires spring loose you will be in a safe position, pull on the piece of wood and wind off the rest of that serving. Repeat this procedure at the other end of the sample. Remove the sample from the vice and lift no more than two or three full-lock wires with a spike and wind them off the sample. Leaving the next few wires in place, remove another two or three wires a short distance away and repeat round the rope sample. In this way, the condition of the lubrication and wire interfaces between the two outermost layers can be examined without undue springing of the sample. The remainder of the full-lock wires can then be removed and placed together. The second layer can be removed by the same method, after which the layers down to the centre of the rope may spring and become over-laid. The condition and lubrication of each layer should be examined as the remaining wires are stripped off and those in each layer kept separate. If necessary, the various

74

Figure 35.

Characteristic form of a wire in a stranded rope

layers may be identified by the wire diameters and by the helical pitch of the wires. A final comparison between the number of wires in each group and the number specified by the manufacturer will ensure that no wires have been placed in the wrong group. If any cracks or fractures are found during removal or examination of the

wires, their nature (fatigue, tension, etc) and position (next to the fibre core, at strand contacts, etc) should be carefully noted together with the exact point of origin of any fatigue cracks (at strand contacts but directly on opposite side of wire to nick, etc). Such observations should enable the examiner to decide the cause of the cracks or wire fractures; for instance, the presence of a fatigue crack directly on the opposite side of a wire to a nick would suggest that accentuated secondary bending (p 89) was responsible, and if several cracks are found at similar positions then the matter is definitely proved. Cracks and fractures can be studied more clearly by using a ropeman's magnifying eyeglass (Fig 33b). Any corrosion scale should be noted and its effect on the steel checked; at selected places the scale should be scraped off the wire with a penknife or other suitable tool and the size and depth of any pits underneath the scale should be explored by means of a scriber (Fig 33c) or similar instrument. Any wires that are not to be tested in testing machines should be bent by hand several times in various directions, in an effort to disclose any hidden cracks. If a wire breaks during such bending the nature of the fracture, its location (with respect to the rope structure), and the location of the point 75

Ropeman's handbook

of origin of the crack (with respect to the various sides of the wire) should be noted if at all possible. The ropeman should be able to recognise such locations in a wire, even after the wire has been removed from the rope. A wire that has been taken out of a stranded rope has a particular wavy form; it will show alternate large and small bends as in Fig 35. The large bend is the part that lay on the rope exterior where the bend of the wire around the strand is in the same direction as the bend of the strand around the rope (both having the hollow side of the bend towards the rope centre); the two bends add together to give a large bend. The small bend is the part next to the main core, where the above two bends are in opposite directions and tend to cancel out. The nicks at strand contacts will be found about half-way between each large and small bend (ie about half-way between the outside of the rope and the part against the main core). External wear will be found on the crown; namely, on the outside of the curve at each large bend. (The inside or hollow side of the curve at the large bend is the 'underside' of the crown - the part contacting the inner wires or strand core immediately underneath the crown.) When studying worn, nicked, or corroded wires it is important to realise that a wire is no stronger than its weakest part. A condition in which deep corrosion pits are spaced at short intervals along a wire, with good wire between, is as serious as continuous pitting of the same severity. A narrow strip of severe wear along one side of a rope is very nearly as serious as wear of similar severity extending around the rope, for all outer wires will eventually pass through the strip of wear as they spiral around the rope.

Rope examination

(a) Wire waisting Figure 36.

(b) Fractured ends Stages in the breaking of a wire in tension

After test, the wire fractures should be carefully examined. A normal wire, without defects, will form a waist when it is just on the point of breaking (Fig 36a); the two broken ends will show this waisting and a typical 'cup and cone' appearance (Figs 36b and 37a and b). If defects such as severe wear or corrosion are present a more brittle type offracture will be obtained (Fig 37c and d).

Wire tests at testing centre

After the sample has been dismantled a proportion of each size or layer of wires should be cleaned and then straightened on a wooden block by means of either a wooden mallet or a brass- or copper-headed hammer. Lengths from each wire should then be tested in tension (pulling), torsion (twisting) and flexion (bending) as described in BS 236, 330 and 2763:1968. Tensile test

In this test, the breaking strength of each wire is obtained. From this value and the measured diameter of the wire, the tensile strength of the steel can be calculated. From these tests also the approximate breaking strength of the complete rope can be calculated. The average breaking strength of each size of wire is summed to give the aggregate breaking strength of the sample (sum of the strength of all the individual wires). The actual breaking strength is calculated from the aggregate breaking strength by using a conversion factor which is dependent on the rope construction and which can be obtained from the appropriate NCB Specification or British Standard. 76

Figure 37.

Tension fractures of unworn wires {a and b).and severlyworn

wires lc and d)

77

!Wpe examination

Ropeman 's handbook

Torsion test

Non-destructive testing of wire ropes

In this test, one end of the wire is fixed and the other end is rotated at one to two revolutions per second until failure occurs. The number of turns to failure is noted. This test magnifies the effects of corrosion pits, cracks, wear, welds, etc, as twisting tends to be concentrated at such faults and the number of turns to failure is, therefore, greatly reduced (Fig. 38).

Ropemen regularly have to visually examine long lengths of rope within a limited period of time. These ropes are often close to the roadway floor making it difficult for the ropeman to examine the underside of the rope. Non-destructive testing (NDT) methods of rope examination are being developed to help the ropeman to locate defects in a rope whether they are on the surface or concealed in the inner layers. Alternating current (AC), direct current (DC) and permanent magnet types of NDT instruments working on magnetic induction or electromagnetic principles have been designed for examining wire ropes and these are being further developed.

(a) Normal wire tested in torsion

i:. it

The non-destructive testing of a wire rope will not be a substitute for a visual inspection but will be used primarily to locate hidden defects and to draw the ropeman's attention to them.

~~

(b) Worn wire showing localised '"''i,tinc

Figure 38.

Appearance of wires tested in torsion

Reverse bend test

In this test, the wire is bent backwards and forwards in a vice with specially rounded jaws of specific diameters. The number of complete 180' bends before wire failure occurs is noted. 78

79

Types of deterioration in ropes

Chapter 6

1.

Types of deterioration in ropes The main forms of deterioration in rope are as follows: -~rear

(a) Abrasive

- Corrosion

-

Fatigue Corrosion-fatigue Surface embrittlement Accidental damage and distortion, leading to local deterioration.

If a rope is of unsuitable type or construction, some of the above forms of deterioration are more likely to occur. For instance, flexible type ropes hf!ving small outer wires of less than 2 mm (0.08 in) diameter are likely to suffer deterioration by wear and corrosion; ungalvanised ropes working under corrosive conditions are almost certain to deteriorate by corrosion, especially if they are not kept well lubricated at all times.

(b) Plastic Figure 39.

External wear on wires

Wear

Both external and internal wear are bound to occur to some extent in all ropes; but when wear becomes heavy the cause should be found and corrected. It should be remembered that corrosion aids the advance of wear by helping to remove steel, just as wear aids the advance of corrosion by removing the corrosion scale and presenting a fresh surface for further corrosion.

Internal wear

Wires in the rope interior which cross one another are bound to cut into one another to some extent. If they are of opposite direction of lay they will produce short indentations or nicks on one another; if they are of the same direction of lay or in parallel lay they will produce long grooves. Fig 40 shows examples of nicks and grooves. In Fig 40a is shown a normal nick.

External wear

External wear may take the form of abrasive wear (Fig39a), in which metal is removed from the crowns, or it'may take the form of plastic wear (Fig 39b) in which metal is displaced to form fins at the edges of the worn crowns. Abrasive wear suggests that the rope has been rubbing too much against some hard and abrasive surface which has rubbed off some of the steei of the wire surfaces. Plastic wear suggests that the rope has beerr bearing heavily on some hard surface (such as a pulley groove or drum) or, in other words, that there has been too little area of contact between the rope and the hard surface to give proper support to the rope and that the steel of the wire surfaces has been splayed or deformed into fins by the heavy pressure. 80

(a) Normal nick

(b) Twinned nick (c) Scuffed nick Figure 40.

(d) Groove

Internal wear on wires

81

Ropeman 's handbook

Fig 40b shows a twinned nick caused by a crossing wire permanently changing its point of contact with the wire shown to a slight extent, as a result of the rope becoming somewhat loosely laid up at some time subsequent to manufacture. Fig 40c shows a scuffed nick formed by a crossing but very loose wire p1aying against the wire shown. Fig 40d shows a long groove made by a wire of the same direction of lay as the wite in the illustration. When the nicks or grooves become too deep, and there is no corrosion present to explain their depth (for corrosion aids the advance of wear), then it would appear that the wires are being pressed together too heavily or driven together too forcibly by impact. Excessive pressure would, in turn, suggest that the rope is bearing too heavily on some object (such as a small drum or pulley in which case there will probably be continuous plastic wear on the rope exterior); or that it is being pinched (as by a tight pulley groove). Impact would mean that the rope is striking against some object, in which case there will probably be intermittent wear or damage on the exterior. Impact on a moving rope can also produce martensitic surfaces on the wires with subsequent wire breakage (see alsop 96).

How wear leads to breakage

When the round outer wires of a rope or strand (or the round outer rods of a guide rope) become reduced to half their original depth* (Fig 4lb) by external wear or corrosion, there will no longer be any valleys remaining between adjacent outer wires, and those wires will then be of such a shape that they can be readily displaced by overriding one another as shown in Fig 41b~ When the wires become reduced to less than half their original depth they will also be reduced in width and will no longer be in contact with their neighbours; there will then· be spaces or gaps between them (Fig 4lc). Such 'loose' wires are very easily moved about in the rope and very readily override one another. If, in addition, internal wear (or internal corrosion) has removed the 'undersides' of the outer wires and left those wires loose on their inner wires (Fig 41d), then the outer wires will be very loose indeed and will be even more easily displaced. When wires become loose and override one another, they rapidly become broken as a consequence of occupying such an exposed position and being displaced first in one direction along the rope and then in the other as the rope changes its direction of travel and the overriding wires foul obstructions. Thus, if a rope remains in service after it has reached the highly dangerous

* The depth of a wire is measured in a direction towards the centre of the rope.

82

Types of deterioration in ropes

(a) Unworn condition

(b) Outer wires worn to half

(c) Outer wires worn to less than half

(d) Internal wear and corrosion

SMRE

Figure 41.

Loosening of wires in a strand by wear and corrosion

condition in which wires have become loose and displaced, that rope will proceed to fail wire by wire until its strength is so reduced that it can no longer carry the load and the remaining wires then break in tension. A rope IS m this highly dangerous condition when spaces can be seen between or underneath the outer wires. Fig 42 shows six stages of failure, wire by wire, of such a rope (a man-riding haulage rope which broke m serVIce). In Fig 42a the wires are so loose that spaces or 'daylight' can be seen underneath some; in Fig 42b a loose wire has become displaced and bent into a Z-bend; in Fig 42c a wire has broken at a Z-bend; in Fig 42d the broken ends of a wire are protruding from the rope so that they are liable to catch on obstructions; in Fig 42e one of the broken ends has been hooked back on itself as a result of catching on obstructiOns;. m Fig. 42f that end has broken off short leaving a stubby flexiOn (bendmg) fracture at an unworn part between strands which is not the original fracture at a greatly worn crown. Of course, no rdpe should be allowed to reach such a dangerous state where it is actually in the process of breaking wire by wire.

83

I

Ropeman 's handbook

Figure 42.

Types of deterioration in ropes

(a) Severed by wear

(f) Battered fatigue

(b) Flexion

(g) Corrosion fatigue

(c) Tension

(h) Plastic wear

Stages in the break-up of a loosened rope

Wear fractures

When a rope breaks as a result of excessive wear many of the wires will show sharp chisel-end fractures (Fig 43a) denoting that they have been severed or almost severed by wear, but some will probably show stubby flexion (bending) fractures with slightly hooked ends at unworn parts, as in Fig 43b and Fig 44. (Those wires were also severed by wear or broken in some manner at their crowns, but have since lost their original broken ends as a result of their catching on obstructions and being wrenched off.) A fair proportion of the wires will show typical tension fractures at less worn parts, as in Fig 43c. (These are the wires that failed in tension when the rope became so weakened that it could no longer carry the load.) A tension fracture can always be recognised by the waisting (necking), ie the reduction in diameter, that occurs at the broken end (seep 77).

(j) Martensite

Corrosion

Corrosion is the greatest enemy of colliery ropes. It is caused by water spray, steam, fumes, acids, salt, unsuitable lubricants, etc. Any water will cause corrosion if it gets into contact with the steel surfaces; it need not be acid water. Common salt (sodium chloride) is very corrosive and may

84

(e) Fatigue

(k) Sheared end

Figure 43.

Types of wire fractures

85

Ropeman 's handbook

Types of deterioration in ropes

(a) Rope with fracture wires Figure 44.

(b) Fractured end Flexion fractures in a rope

(a) In a six-strand rope reach the rope in the form of sea spray if the colliery is near the shore, or in the form of salty water from the strata in the shaft. In fact, any type of chloride in the water usually makes the water more corrosive. When corrosion affects only a short length of a rope, it is possible that the rope IS being attacked while it is standing idle. For instance, it may be caused by a leaking steam or water pipe or by condensatiOn at the rope hole. m the hooding of an upcast shaft. The high air velocity at the fan dnft and mr seals in a shaft can also displace the rope lubricant (ie scour or suck it from the rope surface) and so encourage the onset of corrosion. Corroskm may attack only the outside of the rope.(external corrosiOn) or may do 1ts work unseen within the rope (internal corrosion). However, it can be controlled.

(b) On a fully-locked wire from a locked-coil rope Figure 45.

External corrosion, severe pitting

pitting and wear would, at first, suggest. The ropeman should, in such a case, suspect the presence of internal corrosion. External corrosion

External corrosion usually takes the form of mild rust or scale and is seldom more serious than it appears, unless winding shocks have contributed to deterioration by corrosion-fatigue (p 94). It may take the form of pitting (as in the triangular strand rope in Fig 45a and the outer wire of a locked-coil rope in Fig. 45b) when it must be remembered that the corroded wires are no stronger than their weakest parts, ie at the largest or deepest pits; or it may occur as edge-pitting, in which some or all of the pits lie at the sharp edges of heavily worn crowns (ie at the contacts between adjacent outer wires). Edge pitting is the more serious fori! means that the corrosion is attempting to enter the rope between the wires. In F1g 45a some of the pits have attacked the sharp edges of the heavily worn crowns and have caused those edges to become serrated or saw-edged. Thus, the rope in the illustration may be in a much worse condition than the external

86

Internal corrosion

Internal corrosion is dangerous, for it may remain unknown, unless the ropeman is aware of the external signs that disclose its presence. Internal corrosion, when severe, loosens the wires by removing their bearing surfaces in the same way as does severe internal wear (p 81) as shown in Fig 4ld. Returning to Fig45a it will be seen that the outer wires are loose; there are spaces between most of them, some are riding high above the level of others and would soon override them, and some are slightly displaced so as to leave a large space at one side and none at the other. Corrosion has definitely entered that rope and has attacked the undersides of the outer wires, leaving those wires loose on their inner wires, as in Fig 41d; in fact, the rope is approaching the highly dangerous condition of the rope shown in Fig 42. 87

Types of deterioration in ropes

Ropeman 's handbook

Corrosion fractures

When corrosion is so severe that the wires are reduced to the extent that they can no longer carry their load, they will break in tension and develop tension fractures (with waisting) of the type shown in Fig 43c. However, the corrosion pitting and scale may mask the waisting and make it difficult to recognise the type of fracture (Fig. 43d). When a broken wire is so reduced by corrosion \hat it could no longer have been expected to carry Its load, the ropeman can assume that it has broken in tension, especially if other wires in the rope show definite waisting at their fractures.

Fatigue

Fatigue is a form of deterioration leading to broken wires which sometimes occurs in ropes that are free from corrosion. If corrosion is occurring at the same time, the wires may break in corrosion-fatigue (p 94) rather than in pure fatigue. Fatirue is not easy to define in a few words but an example will show clearly what it means. If a rope is subjected to a single overload equal to its breaking strength, it will immediately break in tension and its wires will show typical tension fractures with waisting at their ends (Fig 43c). If, however, the rope is repeatedly loaded to only three-quarters of Its breaking strength it will eventually break in fatigue, after a certain number of loadings, and its wires will show fatigue fractures (Fig 43e) which are quite different from tension fractures. Even if the rope is repeatedly loaded to only one-half of its breaking strength it will still break in fatigue, but only after a greater number of loadings because the loadings are not so severe. If the rope is repeatedly loaded to one-quarter of its breaking strength it will probably never break, because the fatigue limit of rope -wire (under conditions of repeated liending to and fro as happens in a rope) is about one-quarter of the breaking strength of the wire. Thus, if the repeated load in each wire can be kept below one-quarter of its breaking strength, the wire and the rope will not deteriorate in fatigue. The repeated load in a wire of a rope is not only its share of the maximum tensile load. To that must be added the shock loads in the wire during use, also the primary bending load in the wire due to repeated bending of the rope over pulleys and drums, and the secondary bending load in the wire due to repeated bending of the wire over other wires in the rope as the tension varies (see next sub-section). It is to cover these extra loads, and the normal loss in strength during service, thatthe Engineer adopts a safety factor (p 104) in calculating the size and breaking strength of rope required. The ropeman need not bother about such calculatiOns; t?e extra loads are mentioned here only to show that the repeated load to which each 88

wire is subjected may be greater than expected. Sharp-edged surface irregularities, such as small but relatively deep corrosion pits, narrow scratches, surface cracks, etc, encourage fatigue because the intensity of load (kgf per sq mm) at the bottom or root of the irregularity is always greater than in other parts of the wire. The ropeman should be aware that in a galvanised rope apparent nicking may be due only to localised displacement of the surface zinc. Secondary bending fatigue

One fairly common cause of fatigue is accentuated secondary bending of wires, which is illustrated in Figs 46 and 47. If a rope is in a well-laid-up condition, all crossing wires will be in hard contact with one another, as in Fig 46a where a wire of one layer (wire B) is shown crossing over two supporting wires (wires Sand S1) while being pressed downwards or loaded by another wire (wire L). Wire B is acting like a small bridge, spanning the valley between wires S and S1, and being loaded by wire L which is probably not situated at mid-span. Provided that all wires remain in hard contact with one another the valley will remain narrow and shallow and wire B will only be bent slightly into it. These are the conditions of normal secondary bending which exist in most ropes and which do not lead to fatigue, otherwise most ropes would deteriorate by fatigue. Now let it be supposed that the rope is loosely laid up or has become loosely laid up, because it was supplied in that condition, or because it became partly untwisted in handling at the colliery or for some other reason. Owing to the looseness, all the wires will have moved apart (as shown to an exaggerated degree in Fig 46b) and the valley between wires S and S1 will

(a) Normal secondary bending in a well laid-up rope (b) Accentuated secondary bending in a loosely laid-up rope

Figure 46.

Secondary bending in wires

89

Ropeman 's handbook Types of deterioration in ropes

be wider and deeper than before; this will cause a greater degree of bending or flexing in the bridge wire (wire B). Also, owing to the looseness, wire Lis now no longer confined in position by its neighbours in the same layer, and will slide down the slope of the bent wire Band take up a position at mid-span as in Fig 46b; this is its most effective position for causing bending in wire B, so wire B will be much more bent than when the rope was well laid up. All this causes pronounced flexing which is repeated every time the rope tension varies and produces a variation in the pressure of wire L. So, in a loosely laid-up rope the bridging wire (wire B) will be repeatedly bent to a much greater extent than in a well-laid-up rope, and a fatigue crack may develop on the stretched side of the bent wire, at Fin Fig 46b. That crack will then be directly on the opposite side of the wire to the nick made by the pressure of the loading wire (wire L). That position of the fatigue crack is the sign that the crack was caused by accentuated secondary bending. This explanation is theoretical. But such cases do occurin practice, and the ropeman should know how to recognise the above sign if he is to become an expert on rope deterioration. Fig 47a shows a rope which broke in fatigue at a part some distance from that shown in the illustration. In the illustration four outer wires have been cut out to reveal that the remaining outer wires were so loose that the two hacksaw blades (total thickness 1.3 mm (0.05 in)) could be slipped underneath them. In Fig 47b one strand of the rope has been placed in front of a mirror so that both sides of the strand can be seen at once; one wire on each side of the strand has completely broken in fatigue at the line of nicks made by the neighbouring strands. But the fatigue cracks leading to these wire fractures did not start in the nicks; all the cracks in that rope started on the opposite side of the wire and some spread across the wire to reach the nicks. This point is best illustrated by choosing a wire which is cracked but not completely broken. In Fig 47c a cracked wire from the rope has been placed in front of a mirror; the crack is directly on the opposite side of the wire to the nick- the sign of accentuated secondary bending. This indicates that the fatigue in that rope was due to accentuated secondary bending which, in turn, was due to either loose or loosened lay. Actually, the trouble in the above rope was due to loosened lay; the rope had become loose at some time after manufacture. This is shown by the nature of the nicking. In Figure 47c the two nicks are not normal; they are twinned nicks, each being made up of two mainly-overlapping nicks. In other words, the contact points between this wire and other wires changed permanently at some time when the rope became loosened. There is even more information to be found in Fig 47c. The two long grooves which cross the crack were made by the two supporting inner wires

90

(a) Loose rope

(b) Fatigg_e fractures and nicks marking contact points. between strands

(c) Fatigue crack starting on side of wire opposite to nick on contact side

Figure 47.

Accentuated secondary bending in an actual rope

(Sand S' of Fig 46). It will be seen thatthese grooves are wider at the crack than elsewhere; this is because the wire was repeatedly pressed down into the valley between the supporting wires and the groqves made by those wires bec~me widened by that movement. The two grooves overlap, and the crack 1s half-way along the length of the overlap; this means that the crack (and the nick opposite) were at mid-span in the small bridge (a very 91

Ropeman 's handbook

greatly skewed bridge). There is a second nick, which has no crack opposite to it; this is because the nick is opposite only one groove, and so opposite a part which was riding right on top of one inner wire and, therefore, at one end of the small bridge where it could not be repeatedly bent down into the valley.

Types of deterioration in ropes

Thus, a fatigue fracture is abrupt, and atleast a small part of its end surface will be smooth and :probably dark in_ colour; these are the signs of a fatigue fracture Ill a wrre, JUst as wmstmg IS the srgn of a tension fracture.

Fatigue fractures

When a wire is deteriorating by fatigue it will show no signs of that deterioration until it has completed more than 90 per cent of the repeated loading necessary to break it in fatigue. Then a small crack will appear on the wire surface, so small and fine that the rope man will have little chance of finding it unless he knows where to look for it. Fig 48 shows an inner layer of wires of a locked-coil rope; there are six fatigue cracks present. As the crack grows deeper the wire (if subjected to bending as are most wires in a rope) will break in the same way as a wire which has been partly sawn

Figure 48.

Fatigue cracks in an inner layer of a locked-coil rope

through and then bent; it will break with a partly splintered end. Fig 49 shows a wire breaking in this way at a fatigue crack. The splintered part of the fracture (Figs 49c and 43e) has nothing to do with fatigue; it shows only that final fracture of the cracked wire occurred in bending. The ~mooth, flat-surfaced part of the fracture is the part that formed one side of the fatigue crack. The smooth part is usually dark or discoloured, because the crack existed for some time before the wire broke. If the cracked wire is not subjected to bending in service, the fatigue crack will extend completely or almost completely across the wire, giving a smooth flat-surfaced fracture with little or no splintered part. In all cases the fracture will be very abrupt or sharp-edged, without any of the waisting found in tension fractures.

92

Fi~ure 49.

Stages in the breaking of a wire at a fatigue crack

If a wire in a rope has been broken for some time, its ends may have rubbed

a~amst one another and become battered (Figs 50 and 43f), so that it is

difficult to recogmse the above details. However, the absence of waisting will suggest fatrgue to the ropeman. If some lengths of wire from the rope snap at unobserved fatigue cracks, when bent by hand, then he will have proved that the rope rs affected by fatigue.

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Types of deterioration in ropes

Rope man's handbook

(a) Distorted outer layer

Figure 50.

Battered fatigue

Figure 51.

CorroSion fatigue

Corrosion-fatigue

Corrosion-fatigue occurs when there is a combination of the conditions favouring both corrosion and fatigue, namely repeated loading under corrosive conditions with insufficient lubricant or galvanised coating .present to prevent the corrosion. There is, unfortunately, no corrosionfatigue limit or level of loading below which rope wire is safe from corrosion-fatigue. Even if the value of the repeated load is kept very low the corrosion may be of a severity or type that will still lead to corrosion-fatigue. However, if corrosion can be eliminated, corrosionfatigue is unlikely to occur. Fig 52b shows corrosion-fatigue in the inner layers of a mainly ungalvanised locked coil winding rope (only the two outermost layers were galvanised). The deterioration, which resulted in a loss in strength of nearly 50 per cent, was not discovered until the outer wires distorted (Fig 52a) and the rope was withdrawn from service. The corrosion-fatigue had been caused by water entering the rope. Corrosion-fatigue fractures

The fractures shown by wires which have failed in corrosion-fatigue (FigS 51 and 43g) are often very similar to those occurring in pure fatigue (Fig 43e) but there will be some degree of corrosion present- though perhaps very litlle. T<J establish definitely whether a wire has broken . in corrosion-fatigue or in pure fatigue it is necessary for an expert to examine the broken ends under a microscope. However, if a ropeman finds wire fractures of the fatigue type in a rope which shows any degree of corrosion, he would be wise to assume that corrosion-fatigue was the cause of the 94

(b) Corrosion-fatioue in inner wires Figure 52.

Corrosion fatigue in a locked coil rope

fractures and take steps to avoid corrosion-fatigue in future. Fatigue and corrosion-fatigue cracks tend to occur in a line along the longitudinal axis of the rope, often on the compression side where the rope is in contact with the pulley or drum, and this symptom may indicate their origin. Surface embrittlement

Surface embrittlement refers to the embrittlement of the worn surface of outer wires that sometimes occurs in service in winding ropes and more often in haulage ropes. There are two types of such embrittlement. Plastic-wear embrittlement

It has already been shown (p 80) that plastic wear will occur on the outer wires if the rope bears too heavily on some hard surface; the metal of the crowns of the outer wires is then deformed or splayed into fins at the edges of the worn crowns as in Fig. 39b. The fins will be britlle and are likely to crack (Fig:S3a). These cracks, being sharp-edged surface irregularities may become fatigue cracks and may extend across the wire causing it to break in

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Ropeman 's handbook

Types of deterioration in ropes

fatigue; on the other hand they may turn through a right angle and extend parallel to the wire (as shown in Fig 53a) and merely cause the fins to flake off. Thus, in the case of plastic-wear embrittlement, it is a matter of chance whether the wire breaks (Fig 53b) or the embrittled fin flakes off.

(a) Cracked wire Figure 53.

(b) Fractured wire

surface of the rubbed wire is reduced from a temperature above 700°C, and the result rs that the surface becomes brittle martensite to a depth of about 0.02 mm. The first trme that the wire is bent the brittle surface will develop a senes of cracks along or near its centre line as in Fig 54a, each crack runmng across the worn crown of the wire and being only about 0.02 mm (0.001 in) deep .. But these cracks are perfect examples of sharp-edged surface megulantres and they wrll certainly become fatigue cracks; it is only a matter of trme. Further, the cracks are formed in the wire itself not in an overhanging fin as in the case of plastic-wear cracks ~nd, consequently, the wire is certain to break in fatigue when the fatigue crack has extended far enough mto the depth of the wire. Thus martensitic embrittlement is an extremely dangerous form of deterioration.

Plastic wear leading to cracks and fracture

Why is the fin brittle? When steel is deformed while cold (cold w?rk) it is made harder and more brittle. Wire-drawing during manufacturers a form of cold work in which the metal is deformed by the dies; but the wire manufacturer takes the precaution of removing most of the brittleness, ie restoring most of the ductility, by subjecting the wire to as many heat treatments as are necessary during wire-drawing. When manufacture IS completed the wire has sufficient ductility but it must not be subjected to further cold work or the brittleness wrll return. Piastre wear rs cold work, for the metal is deformed or smeared into fins. Thus, the deformed metal in the fins is embrittled.

(a) Cracked wire Figure 54.

(b) Fractured wire

Martensitic embrittlement leading to cracks and fracture

Martensitic embrittlement

Martensite* is a very hard and brittle form of steel produced when steel_is heated to a high temperature (ie above 700°C (1290°F) for steels used m wire rope manufacture) and then suddenly quenched. It IS like the steel of which files are made; if a file is dropped or bent it will break, for it has virtually no ductility. If a fast mo~ing rope rubs even lig_htly agamst a metal obstruction, or if a slower moVIng rope gnnds heavily agamst such an obstruction, the resulting friction can heat the extreme surface of the rubbed wires above 700°C. The wire is heated to that temperature only to a depth of about 0.02 mm (0.001 in). As soon as the wire ceases to be rubbed (when it has passed the obstruction) the heat is quickly carried away to the colder metal of the wire just underneath the heated surface. Thus, the * Named after A

96

Martens, a metallurgist.

Figure 55.

Chain pitting on a wire

It is an interesting fact that when corrosion affects a martensitic surface it enters the cracks and chooses to attack the normal steel below the surface rather than the hard martensitic steel on the surface. Thus, a corrosion pit forms at the bottom of each crack and extends to join up with a pit at the bottom of the next nearby crack. The undermined surface then flakes off and the worn crown eventually displays a chain or chains of elongated corrosion pits following the strip or strips of martensite on the surface. Such chain pitting (Fig 55) is one of the signs of martensite; it is different from the normal random pitting shown in Fig 45.

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Ropeman 's handbook

Types of deterioration in ropes

Surface embrittlement fractures

Kinking

Surface embrittlement fractures will always be of the fatigue type because the wires will break only when the original surface cracks become fatigue cracks of sufficient depth to break the wires; but they will always be situated at the worn crowns of the wires and nowhere else. In the case of plastic-wear embrittlement there will be fins present at the edges of the worn crowns and the fatigue cracks will have originated at the fins (Fig 53b). In the case of martensitic embrittlement the fatigue cracks will have originated in the worn crowns themselves; these cracks are often so close together along the wire that a fracture may be of a stepped type extending from one crack to its neighbouring crack (Fig 54b).

A true kink is formed when a rope goes slack, forms itself into a closed loop, and is pulled tight (Fig 56). Normally, a slack rope forms a loop in order to reheve Itself of twist; the twist taken out of the rope is stored in the form of a loop. When such a loop is pulled tight the resulting kink (Fig56c) IS not JUSt an elbow-shaped bend; It IS a short but very tightly twisted spiral, because all the twist taken out of a long length of rope and stored in the ongmalloop (Fig 56a) has been put back into the short length of rope at the kmk (Fig 56b and c). It will be noted in Fig 56c that the rope is very tightly twisted at the kmk or, m other words, the length of lay is shortened.

If the ropeman can obtain some unbroken wires from a rope suspected of showing surface embrittlement, he should bend one gradually and gently by hand so as to stretch the worn crown, closely watching the crown all the time and preferably through a watchmaker's eyeglass (Fig 33b). If the surface of the worn crown is embrittled he will see cracks opening, and he should stop bending the wire or it will break. If the cracks start to open at the edges of the worn crown where there are fins, then the cause of the trouble is plastic-wear embrittlement. If the cracks start to open at or near the centre-line of the worn crown and not at the edges, then the cause of the trouble is martensitic embrittlement.

Accidental damage and distortion Accidental damage and distortion are not really forms of deterioration, but it is very important that the ropeman should realise that they may lead to surprisingly rapid deterioration at the affected part. A rope which has been dented by a blow may appear to be still in reasonably good condition but may break within a couple of months due to the development of fatigue at the damaged part. This is really not surprising. If the damage is such that some wires are permanently deformed into elbow-shaped bends, then every time the load varies during operation the bent wires will be partly straightened and then allowed to return to their bent condition; in other words they will be repeatedly bent at one point as in the case of accentuated secondary bending and they will probably break in fatigue. If the damage is such that some wires or strands are forced apart so as to leave the rope open at that place, then moisture will enter readily and internal corrosion or corrosion-fatigue may develop at the damaged part.

98

Figure 56.

Successive stages in the formation of a kink

If a rope is permanently deformed into an elbow-shaped bend, but with no change in length of lay at the deformation, then the deformation is not a true kink but a permanent bend which may have been caused by irre!!Ular coiling on the drum or in some similar incident. The rate of deteriorati~n of a rope in such a case will depend on the extent to which the individual wires are bent at the deformation.

A kink or permanent bend in a rope is most easily found by looking along the rope, preferably when it is slack. Distortion in ropes

Waviness (or corkscrewing) is a form of distortion usually confined to locked-coil ropes, but it can also affect a stranded rope if it works in too tight a pulley tread (p 118). In this form of distortion the rope ceases to be

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Ropeman 's handbook

Types of deterioration in ropes

straight over a considerable length and assumes a spiral form, something like a corkscrew. Fig 57 a shows a locked coil rope which is slightly wavy; it will be noticed that the bright external wear is concentrated at the crests or high spots of the waves. Fig 57b shows a more pronounced degree of deformation. The depth and length of a wave is measured by placing a straight edge along the rope as shown. There are many contributory causes of distortion, but the subject is not yet fully understood. In locked coil ropes one cause is lack of lubricant between and directly underneath the outer wires; this leads to the outer wires binding or seizing up, instead of slipping freely on one another and on

the underlying wires, with the result that they cannot act as they should. This is the reason why service lubrication of locked coil ropes is so important. Another cause is loose or loosened lay; the inner layers are always trying to rotate the rope around its centre-line so as to unlay themselves and if the outer layer (laid in the opposite direction to the inner layers) is not tightly laid on the)nner layers it will fail to prevent this rotation until sufficient rotation has occurred to tighten the outer wires. In fact, rotation of the rope about its centre-line figures largely in distortion; for a rope which is fixed at both ends can rotate in one direction at one part of its length provided that it rotates in the opposite direction at some other part. In Fig 57c the rope at the distorted part rotated in a direction which loosened the outer layer o£ wires and tightened the inner layers. This tightening resulted in a shortening of that part of the rope so the loosened outer wires had to rise up off the inner layers and overlap one another in order to accommodate their lengths. In Fig 57d the rope at the distorted part rotated in the opposite direction, so as to tighten the outer layer and loosen the inner layers; these inner layers had no alternative but to attempt to burst through the outer layer in order to accommodate their extra

/

Most ropes have some tendency to twist or rotate when loaded, although some types are designed to reduce this to a minimum, for example locked coil winding ropes and multi-strand ropes. The amount of twist is dependent upon the load applied and the length of the rope. In the case of winding ropes operating without balance ropes, the length of rope and the tension decreases as the load is wound up the shaft and, therefore, the amount of twist will vary along the rope's length. Locked coil winding ropes are complex units consisting of a number of different layers of wires. If, during service, the layers cease to move freely, the rope will become out of balance and twist may build up until waviness or corkscrewing develops.

100

1

~---

{a) Mild distortion ar.d (b) pronounced distortion Final distortion of: {c) birdcage type and (d) hernia type

length, so causing a bulge or 'hernia'.

What causes a rope to rotate about its centre line, even when its two ends are fixed?

, SMRE

Figure 57.

Corkscrew distortion in a locked-coil winding rope

Locked coil ropes of less than 38 mm (H in) diameter have fewer layers of wires and consequently, are less easily affected by those factors whrch can cause wa~iness, ie corrosion, drying out of lubricant, pinching in pulleys or incorrect handJina. this is one reason why in modern friction winding installations seve;al small winding ropes are used (multi-rope friction winding) instead of one large rope (single-rope friction winding). (The main advantage in a multi-rope friction winder system hes Ill the fact that the smaller ropes need only a small driving sheave.) Another cause of rotation is a large fleet angle (p 119) because, to take the case of a descending rope, the rope will first land on the flange of the

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Rope man's handbook

headframe pulley and then roll into the tread as it travels around the pulley. This rolling again involves rotation of the rope. Yet another cause of rope rotation, this time on friction winders, is a constant fleet angle due to misalignment of the driving groove and, in the case of a tower mounted system, the deflection sheave. This causes a continual rotation of the rope in one direction throughout the wind. Fractures at damage and distortions

There may be no wire fractures at damaged or deformed parts unless the rope is allowed to remain in use too long after deformation. If wire fractures appear, their type will depend on the nature of the damage or deformation and on the working conditions. For instance, a kinked winding rope will develop fatigue fractures because a winding rope wears only slowly and fatigue will, therefore, have time to develop, but a kinked haulage rope will rapidly wear through at the kink before fatigue has time to appear. The ropeman should study the nature of any deformation which he finds and should try to foresee how the deformed wires will act during further service. Will they be repeatedly bent and straightened and, therefore, liable to break in fatigue; do they protrude above the level of other wires and become exposed to localised wear; have they been pushed aside so as to leave the rope open and subject to localised internal corrosion? A rope which shows distortion will probably not show broken wires at all, but it may cause excessive sheave wear. Runovers

When a haulage rope is run over by a tub or mine car it will be severely dented by the wheels and some wires may be partially or completely cut through (Fig 43k). The rope will, almost certainly, break at the damaged part if that part is not speedily withdrawn from service. Examination of such fractures may show: many wires with tension fractures (Fig43c); some with chisel ends (Fig 43a) if the rope was permanently bent at the deformation; and some with smooth, bright, sheared ends (Fig43k) where tne wires were cut through, or almost cut through, by the tub wheels.

Types of deterioration in ropes

fatigue or corrosion-fatigue will be much more likely in the busy rope. However, there are certain degrees of deterioration that, under any circumstances, cannot be exceeded with safety. Outer wires readily override one another and become broken one by one if they have become loosened by internal corrosion or internal wear or have become half worn through by external wear (p 80). Thus, a rope should not be allowed to remain in service if the outer wires have become definitely loose or have lost about one-third or 33 per cent of their depth. A rope which has lost more than one-fifth of its strength by corrosion or wear may soon break, even if the remaining strength appears to be sufficient for the load. This is because the distribution of the load amongst the individual wires may become very uneven. Thus, a rope should be discarded when the loss in strength by wear or corrosion, or both, reaches about one-sixth or 16 per cent of the original strength. Loss in strength by fatigue or corrosion-fatigue is more serious, because when some wires show cracks or fractures it can be assumed that the other wires (which presumably worked under the same conditions) will very shortly develop cracks and fractures. Thus, a rope should be discarded before the loss in strength by fatigue or corrosion-fatigue exceeds one-tenth or 10 per cent of the original strength. It will be impossible to calculate accurately the loss in strength unless samples are actually tested, as at a Testing Centre. Otherwise it will be necessary to judge the loss in strength less accurately. All broken or cracked wires situated within a length of two rope lays should be regarded as no longer contributing any strength to that part of the rope, for a rope may well break over a length of two rope lays rather than in one place. T-he circumstances to be taken into account in deciding when any type of rope should be discarded are summarised in Appendix 2 but, regardless of any stated limits of deterioration, a rope should be discarded if any doubt exists as to its safe condition.

When to discard a rope

In order to decide when a rope should be discarded it is necessary to take into account the state of the rope and the conditions under which it works. A rope which shows some deterioration but which has done little work may be considered to be still in reliable condition, whereas another rope which shows the same degree of deterioration but has done a great deal of work may be considered to have reached the end of its useful life. The onset of

102

103

'Winding ropes

Chapter 7

(shock loadings, bending stresses, etc) and to allow for normal loss of rope strength dunng service due to detenoratmn. Although the ropeman will not have to calculate the value of the maximum suspended load, it may help him m his work to know what is included in that load.

Winding ropes Table 5

Selection of winding rope

The main items to be considered in choosing a winding rope are:

o The type of rope -locked coil or stranded (round strand, triangular strand or multi-strand). D The type of strand- simple construction with large wires for resistance to wear and corrosion, or compound construction for greater flexibility. o The type of lay - left or right hand, Lang's or ordinary, cross lay or equal lay; the manufacturer will generally supply Lang's right hand lay unless instructed otherwise. D The type of wire- for locked coil ropes, the tensile strength may vary from 160 grade (160 to 189 kgf/mm2) to 200 grade (200 to 239 kgf/mm2) for round wires, and from 120 grade (120 to 144 kgf/mm2) to 160 grade for shaped wires (see NCB Specification 186/1970). For stranded ropes the grades are normally 160 grade or 180 grade (180 to 219 kgf/mm2). D The surface finish - ungalvanised for conditions known to be dry and non-corrosive, but galvanised for conditions known to be corrosive or possibly corrosive. D The size of rope- the diameter of rope required to give the necessary breaking strength. Table 5 will give some guidance when considering the first five items above but, in general, discussions should be held with rope manufacturers who have wide experience of the type of rope best suited to any particular working conditions. As to rope size, the Engineer must calculate the loads to be carried and select a size (diameter) of rope that will have a breaking strength which will give a satisfactory factor of safety. The factor of safety is the number of times the breaking strength of the rope is greater than the maximum suspended load to be carried by the most heavily loaded part of the rope, namely, the part at the headframe when the cage or skip is at pit bottom. For example, on a drum-winder, if the Engineer calculates that the maximum suspended load at the most heavily loaded part of a particular rope amounts to 10,000 kgf and Regulations call for a minimum factor of safety of 6!, he would select a size of rope that would have a breaking strength of at least 10,000x6.5 or 65,000 kgf. A factor of safety is used to take care of extra loadings not usually included in the calculations

104

Factors to consider when selecting winding ropes

Rope service requirements

Rope design characteristics

Strength

Depends on rope construction and diameter, tensile strength of wires and type of core Consider use of: - Outer wires as large as possible - Locked coil ropes - lang's lay rather than ordinary lay - Triangular strand ropes

Resistance to external wear

Resistance to corrosion

Resistance to bending fatigue

Resistance to crushing

Resistance to rotation

Consider use of: - Galvanised ropes - Outer wires as large as possible Consider use of: - Locked coil ropes - Lang's lay, round strand, equal lay constructions - Independent wire rope cores (IWRC) - Triangular strand constructions Consider use of: - locked coil rOpes - Triangular strand ropes - Equal lay constructions - Independent wire rope cores (IWRC) Consider use of: - locked coil ropes - Multi-strand constructions - Ordinary lay rather than lang's lay - IWRC rather than fibre core

In both drum winding and friction-winding installations the maximum suspended load to be carried by the rope or complete set of ropes is the sum of:

the weight of one conveyance (cage or skip) when loaded with the normal heaviest load; o the weight of all attachments above and below that conveyance (chains, adjusting links, detaching hook, cappings of winding ropes and of any balance ropes, etc);

0

105

Wmding ropes

Ropeman 's handbook

o the weight of suspended winding ropes (attached to the conveyance in question) hangirig from the headframe pulley or sheave when the conveyance is at pit bottom. In some shafts. the balance rope is heavier than the winding rope. In these cases, the maximum suspended rope weight is that of the balance rope and winding rope when the conveyance is at the shaft top; c the weight of any balance ropes hanging below the particular conveyance under consideration when that conveyance is at pit bottom; c half the weight of any sheaves running in the loops of any balance ropes below the conveyance. With drum winders or single-rope friction winders the total of the above items will give the maximum suspended load on the single rope involved. In the case of a mnlti-rope friction winder the total of the above items will give the maximum suspended load on the complete set of ropes and it must therefore be divided by the number of ropes in the set in order to get the load on each rope. The maximum suspended load is the same as the maximum static load and is the load in the rope while it is at rest. When the rope is travelling in the shaft there may be sudden winding shocks and changes in speed which may increase the load to about H times its original or static value. Also, bending of the rope around pulleys, sheaves or drums will add further to the load in the wires and secondary bending will add still more. To allow for all these circumstances and also for normal loss in strength during service owing to wear, etc, a factor of safety is chosen. which usually lies between 7 and 10. According to Regulation 17(3) of the Shafts, Outlets and Roads Regulations 1960, the rope must 'withstand a load of at least six and a half times the maximum static load' unless an exemption has been granted by an Inspector. A higher factor of safety is desirable for installations where there is frequent starting and stopping of the rope, eg in shallow shafts, than for installations in deep shafts where there may be fewer winds and therefore fewer decking shocks.

During installation the rope reel should be mounted on a horizontal shaft so that it is free to turn and fitted with some type of effective brake so that Its rotatiOn can be kept under control (p 28). Great care must be taken to ensure that the rope does not go slack as it is led off the reel and onto the wmdmg system. The two ends of the rope must remain secureJy served (p 30) throughout the operation unul fitted to the conveyances or drum otherwise the ends may 'sprin~' or become unlaid and the rope will be 'damaged. If a rope tends to twist the conveyance or 1ts attachments and to displace the rope gmdes It may be necessary to release or apply twist to the rope before finally attaching it to the conveyance. However, no more turns than are necessary should be released (usually not more than one or two turns) other:v1se the rope will become loosely laid up and the loose wires may detenorate m faugue as a result of being subjected to accentuated secondary bending. The uncontrolled use of a swivel for releasing twist in wmdmg ropes IS bad practice. If too many turns are released from a tn~ngular-strand rope, each triangular strand may turn in the rope so as to raise one of Its edges above the surface of the rope. External wear will then become concentrated along that edge (Fig 58) and will be deeper than under normal condihons where It is evenly spread over the outermost flat faces of the strands. If rope twist is a problem at a particular shaft, considerat:on should be giVen to employing one of the non-rotating types of rope, either a multi-strand rope or a locked-coil rope; the preformed type IS non-rotatmg or 'dead' oruy while it is unloaded. When installing a locked-coil rope it is better if the rope can be allowed to hang freely to the pit bottom then, If necessary, one turn or part of a turn may be put in but always in a direction to tighten the cover. '

Installation of winding ropes

The installation of a new rope will probably not be the responsibility of the ropeman but he should be present to enable him to have full knowledge of the condition of the rope after installation. The rope manufacturer should be informed of any damage to the rope during installation. It is a good idea for the Engineer to draw up a definite plan for each shaft giving the step-by-step procedure for installing new ropes and the safety precautions to be taken by all the persons involved. 106

1-

SMRE

Figure 58.

Wear on high edges of triangular strands in a triangular strand rope

107

Ropeman 's handbook

Before installing a new rope it is very important to check that the groove in the pulley or sheave is the correct size for that rope. For a newly installed rope the groove radius should be at least 7! per cent greater than the nominal radius of the rope. A groove which is too small or tight will pinch the rope and may cause rope distortion or wire breakages. One particular stranded rope, working in a tight pulley groove designed to suit the previous smaller rope, distorted into a spiral form during its first week of service. To overcome this, the groove was machined to a size larger than

the measured diameter of the rope and the distortion virtually disappeared within a further week of service. However, in the case of a stranded rope the groove should not be too large for although the shape of a locked-coil rope may alter only slightly in an overlarge groove, a stranded rope will deform and become oval in cross-section. It is also prudent to check the size of the winding drum grooves against the rope size before a new rope is installed, although it is unusual for a drum to wear sufficiently to require machining. During installation and withdrawal of ropes, the socket should not be wound over the headframe pulley as this procedure may lead to a cracked pulley flange. It is a good idea, when installing a winding rope. to cut off a 2m (6! It) length which has been securely served, well lubricated externally, and properly labelled and to keep this sample throughout the life of the rope as a specimen of the rope when in new condition. The rope man can then refer to the specimen if he wishes to remind himself of the appearance of the rope when new, or to settle any queries that may arise as to the exact size, structure, etc of the rope as supplied. If the ropes are supplied by the manufacturers pre-stretched and already cut and capped to the correct length, the manufacturers could be asked for a short length of the new rope to act as a reference sample. This sample would be in addition to the sample of new rope which must be sent to the Testing Centre, at the time of delivery, to ensure compliance with specification. Capping of winding ropes

Winding ropes may be fitted with either white metal cappings or wedge-type cappings. Whichever type is chosen, the procedures given in Chapter 4 must be strictly followed. Recapping drum-winder ropes

According to Regulations 65 and 67(2) of the Shafts, Outlets and Roads Regulations 1960, every winding rope must be recapped at least once in any period of six months service and any part cut off must 'forthwith be 108

Winding ropes

opened up and its internal condition examined by a competent person' Further, according to Reg67 (1) a length of at least two metres of rope must be cut off w1thm each penod of six months service unless the rope is used for fnct10n wmdmg for wh1eh special regulations apply (seep 110). If, at the date of any recappmg, the preceding capping was done not more than three, four or five months previously, the part to be cut off need not exceed 1 m, 1.2 m or 1.5 m respectively. There are sound reasons for these regulations. In the case of drumoperated ropes it is wise to discard the cape! end at regular intervals for that lS the part most affected by winding shocks. This regular cutting of rope from the cape! end also results in spare rope being paid out from the drum and the whole rope bemgmoved on towards the cape!, with the result that no part remams long at the positions where conditions may be severe. For

example, the part just leaving the drum during decking at bank level (and therefore hkely to be subjected to shocks) is moved on towards the cape! end before fatlgue 1s hkely to occur under normal working conditions. The opemng up and exammmg of recapping samples (the parts cut off) gives much mformatiOn regardmg the condition of the remainder of the rope in

the case of drum-operated ropes (seep 116). Before a recapping sample is cut from a rope, both ends of the sample and each side of the cutting pOSltJOn must be securely served (and also clamped in the case of locked-coli ropes) so that the wires will not slacken or spring during or after cuttmg. The whole rope length should also be examined externally, partJcularly for ev1dence of waviness, displaced or broken wires and looseness of wires. The quantity and consistency of the external lubricant should also be noted. In practice, the two metre recapping sample is cut into two lengths. The one metre len~h nearest to the old cape! is sent to the Testing Centre for detmled exammat10n and for tests on the individual wires (seep 76). The remammg length must be opened up immediately, at the colliery, as reqmred by the Regulat10ns, and carefully examined for any cracked or broken w1res or pronounced corros1on. A careful check for broken wires or corros10n should also be made while the new rope end is being prepared for the new cape!. If necessary, recappmg may be carried out at intervals of less than six months or lengths of more than two metres maybe cutoff. On some mstallatlons 1t mal' be beneficial to move the rope forward more than two metres to ensure a s1gmficant change in rope positioning. When a rope 1S found to have broken w1res at the cape! end it is advisable to cut off a long length In an attempt to discard the affected part of the rope. Frequent recappmg wlll then keep the matter under review. After recapping a drum-operated rope it is usually necessary to take the tenswn off the part of the rope at the drum so that spare rope can be paid 109

Winding ropes

Ropeman 's handbook

out from the drum to make good the length cut off at the cape! end. Normally this is done by lowering the conveyance to a point near pit bottom and supporting the weight of the conveyance and suspended rope by means of a gland in the headframe. The type of gland usually employed is the self-tightening wedge type in which any downward movement of the rope should draw two grooved steel wedges further into a tapered frame so as to further tighten them on the rope. These glands should always be assembled according to the instructions given in Chapter 9. Slack rope protection

Modern winding practice includes devices to detect the formation of slack winding rope in conditions where the conveyance is held fast and the winding ·engine continues to move. The rope man should be aware of this equipment when working on the winding ropes. Recapping friction-winder ropes

For friction-winder ropes the regulations regarding recapping are somewhat different since it is not possible to cut off any appreciable length at either of the two cape! ends, for this shortens the working length of the rope. Furthermore, any cutting at the ends does not change the position of the rope with respect to the driving sheave or deflection pulleys. Friction-winding ropes are covered by the Mines (Friction Winding) Special Regulations which require that at each recapping, each capping is 'moved a distance of not less than six inches (152 mm) along the rope towards its other end' at intervals not exceeding six months. The wires at the rope end must be examined particularly carefully for any breaks or corrosion when they are being opened up to form the brush for the new capping. If the length cut off is not being sent to the Testing Centre for tests then it too must be opened up and its wires examined at once, before the rope is recapped and put back into service. Factor of safety of friction-winder ropes

The minimum permissible factor of safety of a friction-winding rope is calculated according to formulae which take into account the degree of bending in the rope as it passes over the winding sheave, the depth of wind (and hence the frequency of winding) and any reverse bending resulting from the presence of deflecting pulleys. The Special Regulations state that 'each set of winding ropes ... shall have a combined breaking strength when first installed of not less than F 1 times the maximum static load that the ropes may be required to carry while persons are being carried or F 2 times the maximum static load that the ropes may be required to carry 110

while carrying the mineral or material they will most frequently carry, whichever is the greater'. F 1 and F 2 are calculated in accordance with the following formulae:

F 1 =l.O+

4.5(R+C) R(l+0.0051-/M)-13.5

4.5(R+C) R(l +0.0051 V M)-13.5 where F1 =the factor of safety while persons are being carried; F2 =the factor of safety while the mineral or material which the apparatus most frequently carries is being carried; R =the ratio of the diameter of the winding sheave to the diameter of the winding ropes; C = 35 where there is Nar a nearby deflecting sheave, or 43 where there is a nearby deflecting sheave; and M = the vertical distance in metres between the level of the top of the highest winding sheave and the level at which the winding ropes meet the suspension gear of the conveyance when at its lowest position in the shaft.

Rope tensions in friction-winder ropes

Multi-rope friction-winding installations in Great Britain operate with the winding ropes directly connected to the suspension gear of the conveyances and not through any form of compensating gear. It has been found that, in order to keep rope tensions approximately equal, it is necessary to keep the rope tread diameters as nearly as possible the same. The deeper the shaft, the more important this is. Large differences in rope tensions can cause distortion or broken wires in one or more of the winding ropes. Most tower-mounted friction winders have groove machining equipment installed and the grooves can be kept in good order by regular checking and trimming as required. When installing new ropes care should be taken to ensure that matched sets of ropes are used to reduce differential stretch to a minimum. Then, provided care is taken to establish the correct rope tread diameters when the ropes are installed the extent of differential tread wear should be small and it is often possible to avoid re-trimming grooves during the life of a set 111

Winding ropes

Ropeman 's handbook

of ropes. However, it is necessary to keep the grooves clear of deposit from the rope. One method of checking the differences in rope tread diameters and rope tensions on multi-rope friction winders is to measure the relative rope travel as follows: Wind the conveyance associated with the ropes to be measured (Fig 59) from the surface to approximately mid-shaft at a steady speed of about 3 to 4.5 m (10 to 15 ft) per second, bringing the conveyance to rest very gradually without any sudden brake application.

Stage 2

Stage1

Surface

Any difference in rope travel can be corrected by trimming, in small increments, the groove or grooves that give the largest rope travel, but if the grooves are dirty it is advisable to trim them clean first. Followina each trimming the conveyance should be wound through the shaft to bedin the grooves and a re-check should be made of the measurements following the procedure outlined above. The point at which trimming becomes necessary is largely determined by experience, but for guidance it is suggested that when discrepancies have reached the limits shown in Table 6 the treads should be trimmed.

Stage3

Check rope marks and measure--Mark ropes

and without any sudden brake application. A straight edge should again be mounted accurately in a horizontai position, so that measurements can easily be taken of each mark relative to the straight edge.

+

+-----1--

Table 6 Discrepancy

Ropes where trouble has been experienced First 12 months

Second 12 months

6 mm (~in) 3 mm (!in}

Hopes where trouble has not been experienced

Mid-shaft

First 12 months Second 12 months ·

10 mm (i in) 6 mm (~in)

Note: A new rope will generally tolerate more inaccuracies than one that has been in service for some time.

Pit bottom 'Distance A should be a1: least 'tWo to three drum revolutions equivalent

Figure 59.

Method of checking rope tread diameters and rope tensions on multi-rope friction winders

With the conveyance at mid-shaft, mark the ropes at some convenient place, say ground level in the case of tower winders. The marks can be made by pencil on a chalk background and should be in a horizontal line; this is usually achieved by using a straight edge and spirit level but if site conditions permit it would be advantageous to have permanent straight edge supports available. Having marked the ropes, the conveyance is then wound steadily up the shaft for two to three drum revolutions until the rope marks are at some convenient level such as, in the case of tower winders, near the drum or deflecting sheaves, the winder again being brought to rest very gradually 112

Equalisation of the groove treads can usually be achieved by this method to within 1 mm (1/32 in) of rope travel over a distance of two to three drum revolutions. In order to assist in making a detailed assessment of this method of checking rope tensions and tread diameters, a record should be kept of the following: - the actual measurements and the date of checking; - the date of trimming of each groove.

Statutory examinations Three main types of examination are required by Regulations for ropes 113

Ropeman 's handbook

employed in carrying persons through a shaft, staple pit, or unwalkable outlet. They are: o the daily examination of winding gear, including ropes [Reg 19(2) of the Shafts, Outlets and Roads Regulations 1960 and Special Regulations for Friction Winding.] o the special examination of ropes [Reg 19(3)]. o the examination of recapping samples [Reg 67(2)]. Additional examinations may be prescribed by the Colliery Manager in his scheme of systematic examination and test in accordance with the Coal and Other Mines (Mechanics and Electricians) Regulations 1965. The daily examination of the rope

In this examination the rope must be given an overall inspection sufficient to confirm its safe condition. The ropeman must look for major faults such as broken wires, damage, distortion, etc while the rope is run slowly past him at a speed of about H m (5 ft) per second. If he observes any such fault, he should stop the rope and make a detailed examination of the affected part. If he already knows that the rope shows such a fault at a certain part, he must stop the rope at that part during each daily examination and make a detailed examination for any worsening of condition or advance of deterioration at that part. The rate of deterioration at a damaged area or fault may be so rapid that it would be dangerous to delay detailed examination of the affected part until the next Special Examination. The special examination

This is the really effective examination as regards keeping a watch on the gradual advance of deterioration at all parts of the rope. In the case of a drum-operated rope the ropeman will already have information as to the type or types of deterioration affecting the inside of the rope, from the opening up and examination of recapping samples. In the case of a friction-winding rope the recapping samples may or may not have supplied him with this information. (Recapping samples of friction-winding ropes may not in all cases supply reliable information as to the condition of the remainder of the rope.) During the Special Examination he should, amongst other things, search for external evidence of the advance of any internal deterioration shown by recapping samples. For instance, if the recapping samples show that internal corrosion has commenced at the cape! end, the ropeman should search for evidence of more advanced internal corrosion at other parts of the rope; such evidence is the loosening of the outer wires (p 83). He must also look for less expected forms of deterioration, for distortion and for damage. 114

Winding ropes

According to Reg 19(3}of the Shafts, Outlets and Roads Regulations 1960, a special examination must be carried out at least every thirty days. In this examination the rope must be stopped, cleaned and examined 'at all places particularly liable to deterioration and at other places not more than three hundred feet (90 metres) apart throughout its length .. .' Ropes should be examined with particular care at the following points: Drum-winder ropes

Friction-winder ropes

For each rope: 1 the capel end; 2 the part on the headgear pulley when the conveyance is at the bank; 3 the part leaving the drum when the conveyance is at the bank; 4 the part on the headgear pulley when the conveyance is at pit bottom; 5 the part leaving the drum when the conveyance is at pit bottom; 6 any other parts particularly liable to deterioration, such as a part leaving any hooding of an enclosed shaft at the ends of winds, the parts situated at the ends of any scroll on a drum, the anchorage of the dead end of rope to the drum, the part opposite a fan drift when the conveyances are parked; 7 any section of rope that is not easily accessible, eg the length of rope between the drum and the headgear pulley on the overlap position, and the length of rope from the capel to the headgear pulley.

For each rope: 1 the capel ends; 2 the part at the headgear pulley or deflecting wheel (if any) when the conveyance is at the bank; 3 the part leaving the driving sheave when the conveyance is at the bank; 4 the part on the headgear pulley or deflecting wheel (if any) when the conveyance .is at pit bottom or at the most frequently used inset; 5 the part leaving the driving sheave when the conveyance is at pit bottom or at the most frequently used inset; 6 any other parts particularly liable to deterioration, eg the part opposite a fan drift when the conveyances are parked; 7 any section of rope that is not easily accessible, eg the length of rope between the capel and the deflector or driving sheave when at bank.

It is important to examine the rope at the point where it emerges from the

socket at the cape! end. Broken wires at this position would suggest a faulty capping. (it is to facilitate such examination that any serving protruding from the socket of a winding rope should be removed as soon as the capping operation is completed as stated in Chapter 4.) For the Special Examination, suitably designed inspection facilities should be provided at the surface level such that the ropeman can be in a position to clearly see and handle the rope without having to divert any of his attention to his own safety. Good standards of artificial lighting should be available and, if possible, tb.e ropeman should have an assistant helping to watch one side of the rope as it is run slowly past. There is an understandable tendency for ropemen to run the rope through their hands, for the fingers are very sensitive in noting any changes in rope shape, 115

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Ropeman 's handbook

displacement of wires and, of course, broken wires. A more suitable method with locked coil winding ropes is to use a looped wire as shown in Fig 24. However if, on a stranded rope, there is a suspicion that there may be broken wires in the valleys, a further test would be to hold some cotton waste loosely against the rope; a broken wire will then catch and retain some of the cotton waste with less risk of injuring a finger. If the ropeman suspects loose wires or internal corrosion he should carry

out the hammer test as described on page 74. When the rope is stopped at one of the parts to be examined in detail the ropeman should note its general appearance, measure its diameter and lay

length and make a detailed examination of the rope exterior as described in Chapter 5 over a cleaned length of at least 1 m (3ft). If he finds a single loose wire in a stranded rope he could make an effort to check if it is broken inside the rope by attempting to release any broken end; for instance he could insert a flat spike or flat tucking tool between the affected strand and its neighbour, first on one side of the affected strand and then on the other, so as to prise the strands slightly apart and allow any broken end to fly out. If he finds a broken wire in a stranded rope he should break it off by repeated bending through 180 degrees in line with the axis of the rope and examine it under his magnifying glass (Fig 33b) in order to find the cause of breakage. This can be determined from the type of fracture (fatigue, tension, etc); the position of fracture (next to the fibre core, at the nicks between strands, etc), and by noting the side of the wire on which any fatigue crack started (where corroded next to the fibre core, directly opposite to a nick, etc). For instance, if the wire shows a fati211e fracture at the nicks between strands but with the crack starting on the o~posite side of the wire to the nick, then it could be deduced that the wire had broken in fatigue due to accentuated secondary bending. If corrosion scale is present he should choose a badly affected wire and scrape off the scale. with his penknife. If he finds corrosion pits under the scale he should explore their size and depth with a scriber (Fig 33c}. If he already knows from the examination of recapping samples that internal corrosion has commenced,

he should compare the looseness of the wires at the part of the rope 1mmedmtely above the cape! with the looseness at all other parts of the rope. This will give him information as to whether internal corrosion is more advanced at these other parts of the rope. Finally, he should re-lubricate the cleaned part of the rope and have the rope moved slowly untJI he reaches the next part to be submitted to detailed examination. The examination of recapping samples at testing centres

The examination of recapping samples is the most searching and detailed of the three examinations. It is carried out on part of the length of rope cut

116

off during recapping (the one metre length nearest to the old white metal capping or safety block) and is usually done at a testing centre. The procedure must include a thorough external and internal examination of the whole sample as described in Chapter 5 and samples of each size or layer of wires tested as also described in Chapter 5, and in the British Standard or NCB Specification for the type of rope concerned. The ropeman responsible for the rope should be informed of the results of the examination and test. Keeping records

There is no point in making a careful and useful examination of a rope or recapping sample if the results are not recorded. The entry in the Record Book must be informative and give a summary of the findings. However, in addition, the enthusiastic ropeman will wish to keep his own records in which he can include all the details which will be useful to hiru in future examinations, and reminders as to what he should look for with special care. He should keep a separate small notebook for each of his ropes and write on the cover the exact recognition details of the rope concerned, for example: 'Lady Macbeth Colliery- No 1 Downcast Shaft- East or Overlap Winding Rope (or, in the case of a friction winder, ·"No 3 Winding Rope") -Installed 6.6.74.'

On the first page of the notebook he could enter the details of the rope, for example: 'Details of rope 38 mm diameter- galvanized, triangular strand 6x22 (9/12//::,) 160 grademinimum breaking strength 81.1 tonnes- makers, Z Ropes Ltd- received at mine 15.3.74- Order No 1234- Reel No XYZ.'

Then he could enter the result of his examination of a sample cut off at the time of installation, so as to record the condition of the rope when new, the size of the wires, and any faults which might lead to trouble later, for example: 'Rope sample at installation, 6.6.74 Diameter 38 mm. Lay 267 mm. Well lubricated throughout, except for fibre core which was nearly dry. Corrosion may occur next to fibre. Outer wires 2.64 mm, inner wires 1.63 mm diameter, over zinc coatings. Note: Report dryness of fibre core.'

The next entry might be the findings of the first Special Examination and might read: 'Special Examination, 5. 7. 74 Diameter 38 mm. Lay 267 mm throughout. Externallubiicant rather dry and dusty. Outside of rope slightly discoloured over 20 m next to capping, but no rust. No looseness.'

117

Ropeman 's handbook

Eventually the rope will begin to show some deterioration and the entryfo" an examination of a recapping sample might then read: 'Recapping Sample, 5.12. 75 Diameter 36 mm. Lay 269 mm. Outside: well laid up, lubricant dry and dusty, zinc blackened, no corrosion of steel. Outer wires (2.64 mm diameter) measure 2.39 mm at worn crowns. Inside: fibre core and adjacent wires quite dry, with blackened zinc coatings and mild pitting of steel of both outer and inner wires next to fibre. One inner wire broken. Looks like corrosion-fatigue. Corrosion getting through zinc to steel, lubrication needs looking into.'

In this way the ropeman can use his notebooks to remind him of what he found in his last examination of a particular rope, and to remind him of what he should especially look for in his next examination of that rope. If he keeps a separate notebook for each rope and puts the date above each entry, he will be able to refer to the condition of any rope at any time without delay or confusion. The entry in the Record Book can then be a summary of the important points of the entry in the notebook, leaving out the reminders, etc. If the ropeman is called upon to give his opinion on whether a rope should be discarded at the next week-end or allowed to remain in service for a further period, he can refer to his notebook and use

its contents in framing his advice. Types of deterioration affecting winding ropes

Table 8 lists the main types of deterioration found in winding ropes together with the possible causes, depending on the position and extent of the deterioration, and some suggested remedies. The main points are discussed below. Wear

When external wear on a winding rope is heavy and of the abrasive type it may have been caused by the rope vibrating excessively and striking some

obstruction such as the edge of the rope hole in the engine house or the detaching plate in the headframe. Such vibrations can be caused by the cross-over points on multi-layer winders or by irregularities on the drum surface, such as the timber saddles sometimes fixed to the drum surface to adjust the rope length. (This is not good practice.) Similar wear can also be be caused by the rope slipping on the pulley during braking, etc. Plastic deformation on a rope, either externally or internally, is usually the result of high bearing pressures, against the drum, against other coils, or in

a pulley groove which is too small for the rope. A small ratio (drum to rope), ungrooved steel-surfaced drum will provide only a small area of contact for each coil of rope and could cause plastic deformation. 118

Wmding ropes

The values given in the following table are the minimum drum and pulley/rope diameter ratios recommended for all winding ropes. Table 7

Minimum drum and pulley/rope diameter ratios for winding ropes

Locked coil ropes

Stranded ropes

Rope Size

Ratio

less than 26 mm (1 in) 26--44 mm (1- H in) more than 44 mm (H in)

80 100 120

All sizes

80

Alternatively, the wear may be a combination of plastic deformation and abrasion as a result of the rope bearing heavily against the flange of the pulley, or against the next coil on the drum when the rope makes its largest fleet angle with the pulley; this angle should not exceed H degrees (1 in 38). A round strand rope which coils on top of itself in two layers on the drum will tend to show plastic deformation, for there is only wire to wire contact, of very little area, between a coil of rope in the top layer and coils in the under layer. A triangular-strand rope or a locked coil rope has a greater bearing surface and a change to such a rope may avoid further plastic deformation. Such damage may also be caused by a pulley groove which is the wrong size for the rope; the diameter of the groove should be not less than 2! per cent greater than the rope diameter. If a rope is subjected to corrosive conditions as well as wear, the rate of deterioration will be increased. The external wear will continuously remove the outer layer of corrosion products leaving fresh metal open. to attack whilst corrosion will deepen further the nicks and grooves at contact points between wires within the rope. Corrosion

The most efficient method of preventing corrosion is, of course, to remove all causes of corrosion, but that is not always feasible. However, leaking pipes should not be allowed to blow steam on a rope, nor should water be allowed to drip on a rope if it can be collected and led elsewhere. The parking positions of the conveyances during idle periods should be changed from time to time so as to prevent any one part of the rope length being exposed to the most corrosive location for too long. Ropes should be kept well lubricated at all times, as a defence against corrosion, unless there is a sound reason against lubrication. For instance,

the outside of a friction-winding rope must not be permitted to become 119

Ropeman's handbook

Winding ropes

greasy in case it slips on the driving sheave, but the Engineer may agree to different parts of the rope length being lubricated at differenttimes, using a thin proprietary oil which will penetrate the rope to some extent and which can be wiped off the exterior before winding is re-started. In general, only rope lubricants should be used on ropes. Special lubricants exist which contain additives to improve their usefulness (p 45), such as substances that help to prevent corrosion (rust inhibitors) and those that get the lubricant into direct contact with tbe wire surface even when the surface is wet (water repellents). Rope manufacturers and oil companies will advise the colliery on the use of such lubricants. Every effort should be made to ensure that · the service dressings are compatible with tbe manufacturer's original lubricant.

Fatigue

Fatigue is one of the causes for the premature discard of winding ropes. The onset of fatigue can be delayed if precautions are taken to avoid wmdm~ shocks, sharp bending of the rope around pulleys and drums of msuflicient Size (p 118), loosening of the lay of the rope with consequent accentuatiOn of secondary bendmg and faults in rope design. Severe rope oscillations, indicated by peaks on the decelerometer records for that installation (Fig 61) cause increased stresses in the rope leading to broken Wires either throughout the workmg length or localised at the cape! as a result of Sideways flexiOn. The mouth of a white metal socket or the narrow end of cape! wedges should always be smoothly radiused.

The best defence against corrosion is the nse of ropes of galvanised finish. Even if there were no lubricant present, the zinc coating on the wires of such ropes would protect the steel for many months under corrosive conditions, but eventually tbe zinc would be corroded away. Unless there are sound reasons to the contrary (eg friction winders) galvanised ropes should be kept well lubricated at all times. Under such conditions the zinc coatings will protect the wires throughout the life of the rope except, perhaps, on the rope exterior where tbe zinc may be removed by wear to an extent which permits corrosion of the steel. The exterior, however, can always be readily examined.

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121

Ropeman's handbook

Winding ropes

If, at the beginning of a wind, the cage is accelerated smoothly, the resulting winding shocks will be small. If, however, slack rope or slack chains are abruptly snatched tight, the load on the rope may be doubled for

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Corrosion-fatigue

Corrosion-fatigue occurs in conditions which favour both corrosion and fatigue. It is the most dangerous form of deterioration since there is no lower limit of loading below which the rope wire is safe from such deterioration. However, if corrosion can be eliminated, corrosion-fatigue cannot occur and only the possibility of pure fatigue remains. Thus, the first step is to eliminate corrosion by using galvanised ropes, by keeping the rope well lubricated at all times (unless there are sound reasons to the contrary) and, if possible, by the removal of the cause of corrosion. Distortion

The likelihood of distortion will be reduced if the rope is kept tightly laid up, if the pulley tread is within the correct limits for the rope (p 119), if the fleet angle does not exceed H degrees and if the outer wires are not allowed to become seized through lack of lubricant (NB The authority of the Engineer must be obtained before any attempt is made to lubricate a friction-winding rope, p 49). Waviness has little adverse effect on the breaking strength of a rope, but the decision to allow the rope to continue in service or to be replaced should be taken in consultation with specialists (eg the rope manufacturers). The decision will be based on operating duties, the length and depth of the wave, the rate of development and its position in the rope. Hernias and birdcages have a different effect from that of a wave on the strength of the rope and the rope should be removed. Kinking can occur only while a rope is very slack and the only time a winding rope is likely to become so slack is during installation, recapping, cage suspension changes or cage changing. Thus kinking can usually be avoided by preventing slack rope. 122

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a) excessive rope vibrations caused by misaligned rigid guides or uneven drum surfaces, or b) too small a drum or pulley diameter, or c) excessive looseness in rope; secondary bending d) overloading of rope

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removal of the obstruction rubbing at speed against steel obstruction possibility localised, along one side

greater care in rope handling occurrence of slack rop.e

(ii} localised; kink or permanent bend Martensitic embrittlement

more frequent lubrication by more penetrating lubricant fleet angle should not exceed H degrees enlarge pulley groove diameter to at least 2~ per cent greater than rope diameter (i) sometimes localised a) loss of useful internal lubricant, or (hernia), but often b) too large a fleet angle, or throughout length of rope (waviness} c) too small a pulley groove

removal of conditions I ikely to encourage corrosion and fatigue

Distortion (Figs 57, 64)

conditions likely to cause fatigue together with those favouring at least some degree of corrosion at any part

dam8ge by falling object

Corrosion-fatigue

(iv} localised,outerwires only, martensite possibly present

e) mouth of socket or capel wedges check radius of these edges and inform superior so that effective action may not smoothly radiused be taken f) excessive rope vibrations caused improvements to guides or drum by misaligned rigid guides or uneven drum surface

(iii) continued

Possible remedy

Possible cause

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wire brush always very thoroughly degreased before being capped with white metal use correct capping procedures, sockets to NCB Spec 465 and white metal to BS 643 or NCB Spec 483

increase frequency of recapping until cause of broken wires can be found and remedied use correct capping procedures

a) frequency of winding cycle

b) insufficient length of undisturbed rope within mouth of socket c) wires in brush not properly cleaned, causing uneven distribution of load d) lack of penetration of white metal; incorrect white metal, capping temperature or type of socket used

enlarge pulley groove diameter to at least 2! per cent greater than rope diameter

too small a pulley groove

using rope of more flexible construction consider using ropes of equal lay (p 22) checl< loads

Possible remedy

Possible cause

Position and extent of deterioration

Winding ropes- (continued)

Deterioration found

Table 8

(iii) at neck of capel (Figs 29 and 63)

another and at about 140° round rope circumference from one another (Fig 62)

parallel to one

(ii) along two lines

Numerous broken wires, (i) throughout rope all showing evidence of fatigue

Position and extent of deterioration

Winding ropes- (continued)

Deterioration found

Table 8

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Figure62.

Winding ropes

Fatigue cracks (within circles) along.oneside of a locked coil rope (a) Localised (hernia}

(b) Waviness throughout long length of rope

Figure 64.

SMRE

Distortion in locked coil ropes

Maintenance of winding ropes

Front and rear views showing broken outer wires where rope was in contact with corners of wedges. Position of wedges indicated by broken line.

Figure 63.

All winding ropes need to be carefully maintained. The statistics given in Fig 60 reflect the improvement in the condition of winding ropes resulting from their increased care and maintenance. The figures show that only one winding rope broke during the period 1958-76 whereas twenty-nine broke during the previous nineteen years (1939-57 mclusiVe ). Methods of cleaning and lubricating drum-winding ropes and, where practicable, friction-winding ropes are given in Chapter 3.

Fatigue at a wedge capping

Life of winding ropes Martensitic embrittlement

Impact on a moving rope can produce a martensitic surface on the wires with subsequent wire breakage (see p 96). It is important, therefore, to ensure that close to the rope path there are no steel girders or other obstructions which the rope might contact as it oscillates during a wind. 126

Drum-operated winding ropes have a maximum statutory life of 3! years (Reg 17(2) of the Shafts, Outlets and Roads Regulations, 1960)._ This period, however, may sometimes be extended by the Inspectorate m the case of light-duty winding ropes. The decision is based on an examination of the whole rope by an Inspector and on the results of SMRE tests on a recapping sample sent to them at the request of the Inspector. 127

Ropeman 's handbook

Friction winding ropes are covered by special regulations and are at present limited to a maximum statutory life of two years (Special Regulations for Friction Winding).

Chapter 8

The premature discard of winding ropes as a result of different types of deterioration is discussed in Chapter 6 and summarised in Appendix 2.

Balance ropes Selection of balance ropes

Balance or tail ropes are employed to balance the weight of the winding ropes on each side of the drum or of the rope on each side of the friction-winding sheave. Each end of the balance rope is attached to the bottom of one of the two conveyances and,, consequently, the rope hangs in the form of a U-shaped loop which must bend sufficiently sharply to fit within the distance between the centres of the two conveyances. (The ratio of distance between conveyance centres to rope diameter should normally be not less than 25: 1.) Thus, a flexible rope is required, and usually one that has a similar weight per metre to the winding rope it has to balance. If it is to work on a friction-winding installation, its breaking strength must be at least six times its total suspended weight; this is also recommended for balance ropes on drum-winding installations. Further, it should be a non-rotating rope so as to reduce the danger of the loop in the sump becoming twisted or snarled. The two types of rope that combine non-rotating properties with flexibility are the multi-strand rope and the flat rope (seep 16-17). The multi-strand rope is widely used. The flat rope has the advantage that it can be bent even more sharply and it is also easier to examine because a high percentage of the wire surface is visible. It is, ·however, more vulnerable to corrosion attack than an equivalent round rope and for this reason flat balance ropes are becoming obsolete. As balance ropes often operate in corrosive conditions they are normally made from galvanised wire. Installation and operation of balance ropes

As when installing winding ropes, it is desirable that the Engineer should draw up a definite plan for each shaft, giving the step-by-step procedure to be followed and the safety precautions to be taken by everyone involved. The same care must be taken to ensure that the rope does not go slack as it is led off the reel and that both ends of the rope remain securely served until they have been properly capped and fitted to the conveyances. Multi-strand ropes are often attached to the cage through a swivel (Fig65) to further reduce the danger of the rope twisting and forming a snarl at the loop. In any case, some positive means of preventing the loop from twisting

128

129

Ropeman 's handbook

Balance ropes

around itself should be adopted. Four systems give satisfactory service. o The baulk system where a timber baulk is threaded through the loop and is designed to break orlift if the rope loop lifts too far. The positioning of the baulk should allow for the loop to rise and fall during normal operations and also permit the necessary maintenance operations to be carried out without the need to disconnect the balance rope.

Open boarded box

o The open box' system (Fig 66) in which the loop of a balance rope is surrounded by a retaining box of timbers (steel g1rders would damage the wires). If twin balance ropes are used, a partitionis usually fitted to separate the two loops. These timbers should not rnterfere with the movement of the rope any more than is necessary, for, although the striking of a rope against timber causes only light wear or polishing on the outside of the rope it can cause heavy internal wear in the form of nicking between the strands (the strands being driven hard together at each impact).

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o The restricting frame system is an alternative to the open box and consists of a number of suitably spaced substantial timber frames adequately braced together and controlling the ropes above the loop. D

Figure 65:

130

Typical enclosed type balance rope swivel

The guide hole system which controls each leg of the rope rather than the loop itself. In this case, a timber-lined slot is used to control the two sides of the rope and prevent twisting or, alternatively, holes are cut in the sump platforms to control the rope in all directions. The slots or holes

131

Ropeman 's handbook

Balance ropes

should be lined with chamfered timbers to allow for both directions of rope travel. They should be large enough to prevent localised wear on the rope and to preclude the wedging of fallen debris which might obstruct the passage of the rope.

Suspension or stirrup

Clamp with chamfered inside edges

Rising loop protection in the form of a monitoring device passing through the rope loop should" also be provided. Types of monitor which have proved to be effective include:

captivated retaining pin

Thimble or bobbin

- a hinged tubular lever; and - a trip wire protected from falling debris by a light structural beam or tube free to lift or hinge out of the path of the lifting rope (Fig 66). The monitor is connected to a warning device or to the winding engine safety circuit and operates if the rope loop contacts the lever or trip wire. The position of the monitor is determined by observation, test and

Two- orfourc\amps

experience.

Build-up of debris, water or other obstructions should not be allowed to come into contact with the balance rope. Where rates of spillage may be high (egskip shafts) mechanised means to remove the spillage are provided in many cases.

Capping of balance ropes

Nowadays, balance ropes are often supplied pre-stretched and cut and capped to the correct length by the manufacturers. The two types of terminal fitting generally used for capping balance ropes are: - white metal cappings for round ropes; and - thimbles and clamps for round or flat ropes.

Figure 67.

Typical terminal fastening for flat balance rope

The method of fitting white metal cappings is the same as that used for winding ropes and is described in Chapter 4. Thimble and clamp terminal fastenings for balance ropes

Balance ropes may be attached to the cage or skip by means of a specially formed pear shaped bobbin or thimble. The free end of the rope is bent around the thimble, then laid back along the working rope and adequately secured by a specified number of two- or four-bolt clamps. The whole assembly is then suspended beneath the cage or skip by purpose-designed suspension links or solid stirrup arrangements. The bobbin or thimble is retained within the suspension links or stirrups by a captivated retaining pin. Fig 67 shows the arrangement for a flat balance rope. 132

Examination of balance ropes It is important that balance ropes are examined regularly. Apart from the daily examination,_ British Regulations do not require balance ropes to be exammed m deta!l every 30 days, as specified for winding ropes, but mamtenance procedures should include provision for the periodic thorough examination of balance ropes. Proper access and adequate lightmg are necessary so that the examinations can be carried out safely and effectively. Where the onsetter can, from his normal working position, observe the balance rope, he should be encouraged to do so in order that any unusual movement may be noted and the cause investigated before damage occurs.

133

Ropeman 's handbook

Balance ropes

Types of deterioration affecting balance ropes Table 9 lists the main types of deterioration found in balance ropes and these are discussed below. Corrosion

The most common form of deterioration in balance ropes is corrosion. When inspecting a multi-strand balance rope, the examiner should look for evidence of external corrosion entering the rope between the strands and for looseness of the outer strands that would occur when corrosion between the layers of strands became advanced. Wear

Internal wear in a balance rope will be heavy if it strikes any shaft fittings, even timber, too often and too violently. It should not be assumed that

c.

there is no internal wear merely because the only evidence of external wear

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or pressure is light polishing of the rope surface. Striking of a rope against timber may give only light polishing on the rope exterior but deep nicking in the rope interior. Fig 68 shows a multi-strand balance rope in which all the inner strands failed in fatigue at a slight permanent bend which showed

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134

Partial breakage of balance rope, in fatigue, following external wear

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Balance ropes

Ropeman 's handbook

only mild external wearresnltingfrom the bend repeatedly striking timbers in the shaft. Should it be necessary, the rope manufacturer may examine the interior of the rope by twisting it between two suitable clamps to expose the interior. The ropeman should watch for any localised reduction in diameter and, if possible, check the behaviour of the loop during winding. In flat ropes, wear and breakage of the stitching strands is fairly common; this leads to individual ropelets becoming detached and calls for re-stitching of the affected length.

Damage and distortion

Occasionally, a balance rope may be damaged by an object falling down the shaft and striking the rope sufficiently hard to displace some of its outer strands. Although the external damage may appear relatively slight, fatigue breaks are likely to develop in the inner wires as a result of the increased secondary bending that will take place. Fig 69 shows one such example four months after being damaged. A damaged balance rope should be regularly and very carefully examined so that any further deterioration, if it occurs, can be detected and appropriate action taken. If spillage in the sump is allowed to build up to reach the balance rope, the

loop will become displaced; it may then eventually form itself into a large knot and fail under holdfast conditions (Fig 70). Methods of controlling spillage and of monitoring any unusual rise in the balance rope loop have been discussed earlier in this chapter.

(a) Damaged outer wires, front and back views

Figure 70.

Knotted balance rope, the result of spillage in the sump

(b) Intermediate strands

Maintenance of balance ropes

Some advice on the care and lubrication of balance ropes is given in Chapter 3 and further information may be obtained from the manufacturers. It is most important that balance ropes should be kept well lubricated since moisture can penetrate the sharp bend at the lowest part of the rope in the sump, thus encouraging the start of internal corrosion. (c) Inner strands

Figure 69.

136

SMRE

Fatigue breaks in inner strands of balance rope as a result of external damage

As with spillage, in all winding installations water in the sump must not be

allowed to rise to the level of the balance rope. Care should also be taken to check and counteract any localised drying effect of shaft heaters on the rope lubricant. 137

Ropeman 's handbook

When to discard a balance rope

The breakage of a balance rope could have serious conseq~ences. The part in the rope length most likely to be weakened by detenoration IS at the loop under one or other conveyance when that conveyance is at pit bottom. The most likely time of breakage, however, is when that conveyance is at, or near bank level when the most weakened part of the rope has to support the ~eatest length of rope. Should the balance rope break under these circumstances it would fall on the lower cage. Also, breakage of the rope would throw the winding system out of balance and might lead to an over-wind or to slip on the driving sheave in the case of fnction-wmdmg. Although balance ropes are virtually out of sight they should never be regarded as out of mind as they are an important part of the wmdmg system. The limits of deterioration· permissible in balance ropes before discard becomes essential are the same as for other ropes and are summarised in Appendix 2. However, friction-winder balance ropes_ must be discarded after three years' service, even if they are apparently still m good condition (Special Regulations for Friction Winding).

Chapter 9 Guide and rubbing ropes Selection of guide and rubbing ropes

The Regulations require that rope or rigid guides be used to guide the conveyances in shafts which are more than 45 m (150ft) deep. Since guide and rubbing ropes are stationary ropes hanging in the shaft and not bending round pulleys they do not have to be as flexible as other ropes. Therefore they are made of large wires to withstand the wear of conveyance shoes or slippers. Rubbing ropes hang between the conveyances to prevent the conveyances from colliding; they are also made of large wires to withstand rubbing and nipping between the conveyances. Nowadays guide and rubbing ropes are of half-locked coil construction since this gives a smooth rope surface, increased strength and excellent locking properties. Round rod guides are becoming obsolete. Guide and rubbing ropes are normally at least 32 mm (H in) in diameter. The rope size will depend on such factors as the depth of the shaft, the applied tension and the safety factor selected by the Engineer. The tension is usually of the order of 1000 kgf (1 tonf) for every 100 metres of depth, and the safety factor not less than five when the rope is new. The tensions on each rope in the shaft should vary slightly, between about 10 per cent above and below the average, so that the ropes in the system will not all sway or oscillate w~th the same frequency. Guide and rubbing rope constructions should be in accordance with NCB Specification 388/1970. Galvanised ropes should be used when the conditions are at all corrosive; even if the zinc coating is removed from the rope exterior by wear, it will remain in the interior to resist internal corrosion. Only ropes designed for the purpose should be used. Old winding ropes are quite unsuitable and may be dangerous; their small outer wires could rapidly become worn through and the broken wire ends foul the conveyance. Installation and attachment of guide and rubbing ropes

As when installing other shaft ropes, it is desirable that the Engineer should draw up a carefully planned procedure to be followed and indicate the safety precautions to be taken by everyone involved. The method adopted should pay particular attention to the following points:

138

139

Ropeman's handbook

c The rope should be constrained from sudden twisting movements as much as possible. c Men should be carefully positioned to ensure that they will not be endangered should the rope move unexpectedly. o Acute bending should be avoided, for these ropes are constructed of large wear-resisting wires. A permanent bend in a rope is liable to suffer rapid and concentrated wear (p 159). o The rope should be installed in a smooth, controlled manner to prevent shock loading. Normally the rope is attached in the headframe by means of a white metal capping or wedge-type suspension gland. These attachments are normally above the supporting structure where there is usually adequate space for lifting, rotating and recapping the ropes. The white metal cappings should be fitted according to the instructions given in Chapter 4. Wedge suspension glands should be fitted in the following manner.

Guide and rubbing ropes

o Grease the BACKS, NOT the GROOVES, of the wedges before placing them in position around the rope. Also, lightly grease the recess in the gland case into which the wedges fit, using only approved greases. DO NOT use tallow, graphite grease or any grease containing molybdenum disulphide, o Insert the wedges and drive them firmly in to ensure that they are down on the rope and starting to grip and that they are level and tight. To prevent burring, a suitably shaped brass or copper set should be used in conjunction with the hammer and care should be taken not to damage the rope when driving in the wedges. When fitted correctly, the tops of the wedges should be approximately H to 2 times the rope diameter above the top of the gland case. Tell-tale clamp

Before assembling the gland, the following points should be checked. o Measure accurately the diameter of the rope at the point of suspension to determine the maximum and minimum diameters. No gland should be fitted to a rope which is outside the tolerances (for locked coil guide and rubbing ropes ±0.75 mm (0.03 in) of the diameter stamped on the wedges). o Check that the safe working load (SWL) stamped on the gland is not less than the static load that will be imposed on the rope. o Check that the assembly numbers stamped on the wedges and the gland case are the same. Gland cases should be fitted only with wedges bearing the same number.

Final position of wedges (1~to2timesrope diameter above top of gland case)

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Dowel holes

Assembling the gland

o Clean the gland case and wedges to remove any protective grease or paint. Remove any traces of rust from the backs of the wedges, the grooves and the recess in the gland case using EMERY CLOTH ONLY. Remove any burrs on the wedges or gland case recess caused in handling, storage or transit. If left, they may interfere with the movement of the wedges. o Thoroughly clean the grease from that part of the rope to which the gland has to be attached and ensure that this part of the rope is straight, clean and dry. 0 Bolt the gland case round the rope at the required position. With all types of suspension gland the JOINT of the casing must be SUPPORTED ACROSS THE GIRDERS (ie the joint shouHbe at right angles to the girderssee Fig 71).

140

Projecting lug

Guide or rubbing rope

Support channels

Figure 71.

Assembly of a spherically-seated wedge suspension gland

141

Guide and rubbing ropes

Ropeman 's handbook

o The two-bolt clamps should then be fitted (NoT four-bolt clamps, which are less efficient). They must be the correct size for the rope and should be bolted on the rope in contact with and at 90 degrees to one another and with the bottom clamp in contact with the tops of the wedges. The clamp bolts, after cleaning and lightly greasing, should be tightened to the torque shown in Table 10. Table 10 Rope diameter

Bolt size

Tightening torque

Load carrying capacity per clamp

16--44 mm

M 20

150 Nm (110 lbf ft)

1 tonne

45-64mm

M 30

450 Nm (330 lbf ft)

2 tonnes

at least 10 or, for any axially loaded threaded portions present, 15, and their service life should be limited to 20 years. Since these weights and rods hang in a corrosive environment they must be very liberally- greased, especially between each weight. It is also helpful to use spacers between the weights. If this is r.ot done, there is a danger of rust building up between the weights and, in time, this can bend or even break the rod. In some cases, usually where there is some limitation on the space available in the sump, the rope is fixed to a girder at one end and tensioned by means of a spring in the headframe or shaft bottom. Such spring tensioners need to be regularly checked and adjusted if necessary, otherwise the ropes could be too slack in hot weather and too tight in cold weather.

The number of contact clamps to be used is derived from the table and is determined by the total load 10 be manoeuvred or supported. In addition to the required number of contact clamps a marker or tell-tale clamp should be fitted approximately 25 mm from the top contact clamp. This space will act as an mdiCator should any rope slip occur. Fig 71 shows a completed wedge suspension gland assembly. Dismantling a gland D

o o o o o o

Make sure the suspended load (ie weight and rope) is properly secure and that slack rope is evident beneath the gland before attempting to release It. Remove the two-bolt clamps. Raise the gland approximately 75 mm (3 in) above the supporting structure. Loosen the gland case bolts. Strike the gland ca~e downwards with a sharp blow but avoid striking the wedges or rope. This will release the wedges in the gland case. Remove the wedges. Remove the bolts from the gland case, split the case and set it aside. If the gland is to be stored all parts should be thoroughly protected with a rust preventative grease.

The ropes are positioned correctly at the top and bottom of the shaft but otherwise, are normally allowed to hang freely. Each rope is tensioned' usual!~ by attaching cheese-weights of the required value. These hang freely m the sump and are carried on weight-rods attached to the rope by smtable glands or clamps. The factor of safety of the weight rods should be 142

Figure 72.

Typical sleeve for guide rope at sump board

143

Ropeman 's handbook

Whatever type of fixing or tensioning is employed, the suspended rope should lead straight out, without any bend, from the cappings or end fixings otherwise fatigue may be induced as the bend is repeatedly increased and diminished by movement caused by the passage of the cage. A suitable form of suspension gland for use in the headframe is one that incorporates a spherical seating or cup-and-saucer type base (Fig 71). Provided such a seating is well lubricated during installation it will permit the capping to align itself with the rope and will also facilitate the regular turning of the rope to ensure that wear does not become concentrated along one side.

Guide and rubbing ropes

The rope wires should then be inspected to ascertain the degree and position of any wear, corrosion, etc. After examination, each cleaned part

should be carefully relubricated. Records of the results of all examinations should be kept, as for other types of rope, including the measurements of rope diameter at various positions in the rope length.

When the rope passes through a hole in sump boards or any other confined space a sleeve, packed with grease, should be fitted to prevent localised wear and corrosion (Fig 72). Examination of guide and rubbing ropes

In addition to the daily examination, guide and rubbing ropes should be examined more thoroughly periodically to check their general condition and the extent of wear and corrosion. The ropes should be examined throughout the shaft and at all positions most liable to deterioration, including those sections above the top landing and below the bottom landing. At each position of examination, the rope should be thoroughly cleaned with a wire brush to remove any dirt, corrosion scale or dried lubricant and expose the wires so that their true condition can be seen (Fig 73).

(a) Appearance of sample as received and before cleaning

(b) Sample after cleaning

The parts of guide and rubbing ropes particularly liable to deterioration, which should be examined on each occasion, include: o the cappings or end fixings (for evidence of slip or movement); o the parts leaving the cappings or end fixings (for broken wires); o parts passing through the holes in sump boards or other confined spaces (for localised corrosion); o any parts showing slight deformation such as a permanent bend (for localised wear); o parts opposite the fan drift of an upcast shaft where the cage may be drawn over to the fan drift by the air current causing one-sided wear on the side of the rope away from the fan drift (Fig 74); o the conveyance meetings (where maximum restriction of air takes place); (Particular attention should be given to ruboingropes which may become flattened in this area.) o at positions corresponding to entry to or exit from receivers; o at intermediate insets. At each position of examination and after thorough cleaning, the rope diameter should be carefully measured in two directions at right angles to one another.

144

(c) Cross-section of corroded rope

Figure 73.

Corroded guide rope

Figure 74.

Cross section of half-locked guide rope showing the effect of one-sided wear

145

Guide and rubbing ropes

Ropeman's handbook

Types of deterioration affecting guide and rubbing ropes

The main types of deterioration affecting guide and rubbing ropes are listed in Table 11. Wear

Since one-sided wear affects all the wires (because of the rope construction), tbe actual loss in rope strength may be far greater than might be expected. The use of brass or phosphor-bronze cage shoes helps to minimise such wear and rotating the rope at intervals helps to equalise it round the rope circumference. Lifting the ropes at intervals helps to change the positions of localised wear and fatigue. Corrosion

If corrosion (Fig 73) throughout the length of the rope is a problem more frequent lubrication or a different type of lubricant may cure the trouble. Any shaft water, even if not particularly corrosive, should be diverted away from the ropes. A watch should always be kept for localised corrosion, even on ropes which are otherwise little affected by it. Localised corrosion may occur in confined spaces such as the holes where the rope passes through the sump boards or at parts where the lubricant is dried by the effect of shaft heaters and more frequent lubrication should be given to these parts.

Maintenance of guide and rubbing ropes

Being stationary ropes and constructed of large wires, guide and rubbing ropes usually give little trouble. Nevertheless, they must be adequately maintained.

-

-

Both guide and rubbing ropes may deteriorate in fatigue where they leave the headframe cappings or fixings. Thus, the position of the capping or fixing should be moved along the rope from time to time. It is better to lift the rope rather tban to lower it, thereby getting rid of any fatigued part near tbe top of the rope, and it is recommended practice to lift it through a minimum distance of H times the length of the headframe capping at intervals of not more than five years. This will also help to spread any effects of localised wear. Cheeseweights in the sump should be inspected regularly to ensure that corrosion products are not building up to an unacceptable amount and that tbe weights are not being fouled by accumulated spillage. Water should not be allowed to collect round the weights since buoyancy effects would reduce the rope tension.

146

147

Ropeman 's handbook

In order to facilitate maintenance it is important that there should be adequate and safe access to the ropes at both the top and bottom of the shafts. When to discard a guide or rubbing rope

As with other ropes, a guide or rubbing rope should be discarded when the outer wires have lost one-third (about 33 per cent) of their depth by wear or corrosion or both, or when the rope appears to be no longer in a safe condition for any reason such as the appearance of broken wires. There is no legal or statutory limit to the length of life of these ropes but it is accepted practice that they should not remain in service for more than 20 years, even if their condition still appears to be satisfactory. In many shafts much shorter lives are obtained.

Chapter 10 Haulage ropes Choice of haulage rope

As with winding ropes, the main factors to be considered in choosina a "' haulage rope are: rope and strand construction, type and direction of lay, tensile grade of steel, surface finish and size of rope. However, the choice is simplified since only two rope constructions (round strand and triangular strand) are normally employed in haulage and only two tensile grades 160 (160 to 189 kgf/mm2 ) and 180 (180 to 219 kgf/mm 2), are available u~der BS 330:1968 and NCB specifications for haulage ropes (see Bibliography). The most important item is, therefore, the selection of a rope size which will give the breaking strength necessary to deal with the maximum working tension (or pull) in the rope and, at the same time, allow a satisfactory safety factor (p 104). The ropeman will not be called upon to calculate the breaking strength required but he might find it useful to know how it is determined (see Appendix I). In deciding between the use of a round strand or triangular strand rope, it should be borne m mmd that the latter type has the larger wearing surface, an Imj:>Ortant pomt m haulage. If the road is at all wet, or if it has been consolidated by spreading chemicals such as calcium chloride then a galvanised rope should be used. '

Installation of haulage ropes

The same care and precautions should be taken when installina a haulaae "' "' rope as when dealing with a winding rope (p 106). If the rope is supplied on a reel then rt should be paid out by revolving the reeL If it is supplied in the forrn of a coil, then it should be paid out by revolving the coil (p 27). The rope should never be pulled out sideways from a stationary coil for that would kink it. '

Capping of haulage ropes

The types of capping used for winding ropes are not, in general, practical for haulage ropes.

148

149

Haulage ropes

Ropeman 's handbook

Zinc, on t!'e other hand, has been proved to be suitable; at loads up to the breakmg strength of the rope the strands do not become buried in their grooves.)

White metal cappings

Since a flame cannot normally be employed underground to melt the white metal and since it is not usually satisfactory to melt the metal at the surface and convey it underground in an insulated container, the white-metal capping is normally used only on haulage ropes that can be capped on the surface, as in drift mines. When it can be used this type of capping is satisfactory and the capping procedure in such cases is the same as for winding ropes (Chapter 4).

The method of making such a capping is described in Chapter 4. The most important pomts to remember when making such cappings are:

Wedge-type cappings

D

These cappings are normally unsuitable for haulage ropes as their size and weight would be excessive and the method of use may cause slackening of the bands.

Only new zinc cone and tail units should be used. Never re-use an old cone and tail unit.

D

The cone must never be hammered in an attempt to drive it firmly into the socket. Such hammer blows could severely distort the zinc cone and prevent it from pulling properly into the socket and gripping all the ~ope strands evenly. The cone-and-tail unit should be drawn into the socket only by applying a load equal, if possible, to the working load.

D

After the capping has been fitted and the socket pulled into place under load, a final coarse serving must be applied to the rope at the mouth of the socket. This serving is designed to prevent the socket becoming slack on the cappmg whenever the rope end is disconnected during use. This final coarse serving is essential to prevent the socket moving back along the rope when the load is released.

Thus, for the inserted-cone types of capping to be thoroughly reliable, the cone must be of zmc, 1t must be grooved and have a tail strand at least 0.7 m (27 in) long.

lnserted cone-and-tail cappings

The inserted cone-and-tail type capping is suitable hr haulage, and works on the principle of inserting a pre-cast zinc cone into the rope end, between the six strands, so as to form a conical enlargement at the rope end which can be held in a conical socket. It is speedy to fit, and has been proved to be reliable provided that three main points in design are followed: o The cone must have six grooves equally spaced around its surface, to take the rope strands, the depth of the grooves being about half the diameter of a strand (see Fig 32a). (If the cone were smooth instead of being grooved, the rope strands would bunch together on one side instead of being equally spaced around the cone. This would give rise to unequal loading oi the strands and, perhaps, to fatigue in the wires of the most heavily loaded strands.)

o The cone must have a tail strand of wires of the required length protruding from its narrow end, to hold it in place in the rope. (This tail strand is laid up into the heart of the rope in place of the fibre core, which is cut out for the required length. If there were no such tail strand to anchor the cone in the rope, the conemightworkits way out of the rope during service.)

o The grooved cones must be made of zinc (ie Zn3 or Zn4 of BS 3436:1961); white metal is too soft for these cones. (Although white metal is excellent for the white-metal type of capping, in which each wire is embedded inthe metal, itis not sufficiently hard for use in inserted cones of the grooved type. The concentrated pressure of each strand against the bottom of its groove is so great that the strand might become completely buried in the groove and thus escape being securely wedged and held between the cone and the inside of the socket. 150

Cone-and-tail units to NCB Specification 353/1966 can be obtained from one of the larger firms of ropemakers. The correct size of cone for the rope must, of course, be used and the socket must match the cone in dimensions and taper. Somewhat similar cone-and-tail units are made to suit the size and tapers of sockets to NCB Specification 461/1965 (BS 463:1958- Sockets for general engmeenng purposes), and these can be used for haulage with their correct type and size of socket when the Engineer so decides. Great care must be taken to avoid the intermixing of components. The sockets and cones of both types are marked with the rope size and sockets to NCB Specification 353 are also stamped w1th the letters NCB. Cones to NCB Specification 353 are coated w1th translucent blue lacquer on their large ends; those to NCB Spec1ficatwn 461 (BS 463) are coated with translucent red lacquer. Recapping of haulage ropes

Regulation 65 of the Shafts, Outlets and Roads Regulations, 1960, reqmres that every haulage rope fitted with a capping (ie ropes other than end!ess ropes) must be recapped at intervals not exceeding six months. In addJtton, accordmg to Regulation 67, if the rope is used for transporting 151

Ropeman 's handbook Haulage ropes

men at least six feet of rope must be cut off in each six-month period and thos~ lengths must be opened up and examined in the same way as for winding ropes. When recapping, the complete old assembly should be removed and a replacement socket fitted. Zinc cone-and-tail units must not be re-used. A new cone-and-tail should be used on each occas10n. The procedure during recapping is similar to that for capping but points to remember when dismantling the old cappmg are: o In white metal cappings, the socket must not be heated above the socket pre-heating temperature permitted during cappmg (p 57). o Sockets must not be hammered to release t~e cone. Hamll?er ~lows on the socket could so distort the basketthat a zmc cone-and-tail umt would be unable to slide properly into the basket and grip the rope strands securely. The cone can be driven out by striking the cut end of the rope with a suitable drift or punch. Examination of haulage ropes

The legislation covering the examinatio~ of haulage ropes us~d ~or carrying men through unwalkable outlets IS the same as that for wmdmg ropes, and is included in the same regulat10ns (see Bibhograph~)- All man-riding haulage ropes should be treated m the same way as wmdmg ropes as reaards maintenance and exammat10n. Thts does not mean that other rope~ used for the haulage of mineral or supplies should be neglected. Thus, the three forms of examination employed for winding ropes (examination of recapping samples, the daily exammat10n of the rope and the special examination of the rope) should be employed also fo.r haul~ge ropes where they are applicable. Examination of recapping samples

The examination of recapping samples is exactly the same as for winding ropes (p 116). External examination

The rope can be examined visually, in good lig~t, w~ile it is runnin$ slowly; particular attention should be paid to any splices m the rope. Kmks and permanent bends in direct haulage ropes are most readily noticed by looking along the rope, especially when It IS unloaded. Cappmgs shouldbe included in the examination, to check that they are not drawmg or pullmg out of their sockets; inserted cone-and-tail cappings should be checked to confirm that the final coarse serving (p 69) is present and m Its correct position hard against the mouth of the socket. 152

Special examination

The special examination should be carried out as nearly as possible in the same way as for wmdmg ropes (p 114). The examiner should clean m~asure, and ex.ami~e the rope at points along its length, looking fo; evidence of d~tenoratwn by wear, corrosion, fatigue, corrosion-fatigue, or surface embnttlement. He should also look for damage, deformation (kmks and bends) and localized deterioration at such places as the tucks in any splices. It IS a sound idea for the ropeman to have available a short S]Jecimen of the rope in new condition, so that he can compare his rope With that specimen. All such specimens should carry a securely-attached label glV!ng the full recogmt10n details of the rope from which it was cut. The roadway should also be examined regularly and frequently for evidence of the rope havmg fouled obstructions, for seizure of pulleys on the floor, roof, or wall, and for other faults that need correction. Safety ropes, as employed with haulage systems, should not be overlooked merely because they do not normally do any work. Their cappings or end attachments should be checked, and note taken of any tendency for the rol'es to be damaged by revolving axles. The rope clamps on man-riding trams should be checked for tightness using a torque wrench at the recommended setting.

Keeping records

Keepin¥ proper records of haulage rope examination is as important as With wmdmg ropes; mdeed these records can often lead to greater Improvements m the case of haulage, for the working conditions are seldom as good as in winding. Apart from making informative entries in the required records, the ropeman should keep for hiS own use, a separate notebook for each rope, the t1tle on the cover of the notebook showing which rope it refers to. In this notebook he can record all details of rope construction, size, lay etc, and the results of all examinations of the rope and of any recapping samples. In the case of endless ropes he can note the dates on which new lengths were spliced in, and any recognition details of the splices which will help him to locate them in future, and thus arrange for regular replacement of the older parts of the rope. A helpful method of locating and identifying splices 1s to pamt them m different colours. To do this, the spliced length should be cleaned, painted and regreased when the paint is dry. Repaint as necessary. Although the paint will quickly wear off the strand crowns it will remain visible in the valleys between the strands for some considerable time. The ropeman can note in his book any improvements in working

153

Haulage ropes Ropeman 's handbook

conditions that he considers necessary, so that he can check later that they have been carried out and record the results obtained. Such notes, for example, might read as follows: >

'Daily examination~ 1.7.75 Rope in good condition except at 7 m from cape!. Bad kink here, with severe wear and two broken wires. Length of 10m cut off and opened up. Dry inside but in good condition apart from wear at kink, where most wires almost worn through. Rope watched while working. Slack rope paid out by engine before empty tubs pushed over brow 7 m from engine. Probably slack rope became kinked on one occasion. Showed engineman and haulage hands the thinned wires at the kink and they agreed to take care in future. Rope recapped to remove kink.'

~

"ro

e

This would be an example of an enlightened examination and action taken, as distinct from a routine one, and is an example of a useful record. An entry in another of the ropeman's notebooks might read: 'Special examination, 3.9. 75 Smallest diameter 26 mm. Lay 190 rom. Outside well lubricated and brigbt. Wear moderate except near mid-length where it was somewhat heavier and brightly polished. Many broken outer wires here, up to ten in 0.5 m lengths. Most broken ends had been knocked off, but some remained and were cut out for examination. All had many fine cracks across the worn crowns. ie martensitic embrittlement. Rope grinding against something. Road examined while rope running. Rope cutting into displaced arch leg. Wall pulley fitted until arch can be reset. Rope reported unsafe and replaced. Bad part opened up and examined. In good order inside, but all outer wires very brittle at worn crowns and nowhere else. Informed under-manager who has deployed men to set back the arch leg.'

This is a much more useful record than merely repeating the entry 'rope in good order' until the rope breaks; for it has resulted in a dangerous rope being replaced and in the cause of the trouble being rectified. No more can be asked of the expert ropeman except, perhaps, that he should note and rectify the trouble before the rope is ruined. However, in some cases the ropeman responsible for haulage ropes has to divide his time between ropes and other general duties. If he finds that those other duties tend to interfere with the regular examination and maintenance of the ropes and their roadways, he should inform the Engineer accordingly.

00

"c. _ e

"~

~

.c

Types of deterioration affecting haulage ropes

Table 12 lists the main types of deterioration found in haulage ropes and these are discussed below. Haulage ropes are particularly susceptible to corrosion and to the various forms of wear and damage. The types of deterioration can be recognised by the same signs as in other ropes and the means of avoiding them are basically the same.

0

N

"mc ""c

ID 0

l"

ID

CIJ .::

U:l:

155 154

Ropeman 's handbook Haulage ropes

Corrosion

Corrosion is the main cause of deterioration in haulage ropes (Fig 75). In wet roadways, water, which may or may not be corrosive, should be diverted away from the rope and supporting rollers and not allowed to accumulate in the roadway. If it does so it will almost certainly contaminate and corrode both the rope and the roadway rollers which, if they are to serve their purpose, should always be free-turning. A galvanised rope is likely to give longer service than an ungalvanised one. Even though the galvanised coating may be quickly worn from the strand crowns, it should remain in the rope interior to give protection there. (a) Cross-section of heavily worn

rope {original diameter shown in dotted liile)

Figure 75.

(b) Heavy external wear causing (i) wires broken at crowns (ii) displaced and broken wires

Severely corroded haulage rope

Wear

Wear on a haulage rope can take several forms. If the rope rubs relatively slowly against the floor, rails or other obstructions, the wear may be purely abrasive, metal being gradually removed from the external wire crowns (Figs 76, 77). Removal of tbe obstructions or guiding the rope away from them by the use of extra rollers should reduce such wear. Because of the working conditions for most hanlage ropes, the outer wires of these ropes should never be less than 2 mm (0.08 in) in diameter, otherwise they will not be robust enough to withstand the wear and corrosion likely to be encountered (Fig 78). Localised wear can occur at a kink or at a permanent bend (Fig 79). True kinking can occur only when the rope goes slack and forms itself into one or more closed loops as in Fig 56. Kinking is much more likely to occur in haulage than in winding because direct haulage ropes may go slack, as when the tubs leave a gradient and enter a level part of the road, or when the rope is disconnected from the tubs. Permanent elbow-shaped bends, somewhat similar in shape to true kinks., may be formed by irregular coiling 156

(c) Outer wires showing the effects of haavywear on the external crowns and 'chisel-type' fractured ends

Figure 76.

Figure 77.

Effect of heavy wear on a haulage rope

Haulage rope showing wires severed by severe external wear

157

Haulage ropes

Ropeman 's handbook

on the drum (a coil in one layer spanning a gap between two open or separated coils in the underlying layer and then being forced into the gap by the pressure of a coil in the overlying layer). They may also be caused by a haulage clip pulling too heavily on an endless rope when the tubs are held back by an obstruction. Kinks and bends are more dangerous than might be thought, for a rope may break within a few shifts as a result of concentrated and rapid wear on the outside of these elbow-shaped deformations. Thus, a rope which has been deformed by a kink or bend should be examined by a competent person to ascertain the degree of damage and decide the action to be taken.

A kink or permanent bend in a rope is most easily found by looking along the rope, preferably when it is slack. When a rope breaks at srich a deformation it gives a characteristic 'echelon' type fracture, each strand being longer than the strand before it and each wire being longer than the wire before it; this is because each strand and wire has been worn heavily along only one side of the rope (the outside of the kink, or bend) and not at one cross-sectiOn of the rope. Most of the wires will show chisel ends (Fig 43a) because they have been worn through, or ahnostwom through. Also,

(a) Gaps beneath severely worn and corroded crowns of outer wires

(b) Severely worn rope

(c) Severelv corroded rope Figure 78.

SMRE

Deterioration of small flexible haulage ropes Figure 79.

158

Stages of deterioration at a kink in a haulage rope

159

Haulage ropes

Ropeman 's handbook

the most heavily worn strands will be the two whose fractures lie half-way along the rope fracture; they are the two that lay on the point of the elbow and they were the first to break. The longest and shortest strands at the rope fracture will be the least worn and the last to break; in fact one of these may be pulled out straight at its end because it was the last of all the strands to break. These points are illustrated in Fig 79 which shows a kmk at four different stages of failure in the same rope.

-

Similar concentrated wear can occur on the raised strands of a badly made splice (Fig 80a). Trouble can also be caused at a splice if the ends of the tucked strands are not pushed well into the centre of the rope (Flg80b). A protruding end can catch against obstructions so that the whole tucked strand is pulled out, with the result that a holdfast and rope fmlure are likely to occur as illustrated in Fig 81.

(a) Unevenly laid strands

Enlargement of the outbye side of the fracture.

Figure 81.

Haulage rope breakage caused by faulty splice

(b) End of tucked strand protruding through outer strands

Figure 80.

Examples of badly made splices

martensitic embrittlement. He should first remove the obstruction, or Surface embrittlement

Some haulage ropes deteriorate as a result of surface embrittlement. This may be caused by the rope rubbing heavily against metallic ob~tructions causing martensite (Fig 54) or by heavy pressure on drums causm~ plast1c deformation (Fig 53). If the ropeman observes that a low grrder, a · protruding arch leg, or a seized road roller has become grooved by the rope, he should at once realise that the rope IS hable to have suffered 160

guide the rope past it by means of free-running rollers, and he should then exaJnine the rope closely with his magnifying glass for fine martensitic cracks on the worn crowns. If he finds such cracks he must keep the rope under frequent examination and ensure that it is withdrawn from service as soon as wires begin to break at the worn crowns. It would be better, of course, if the ropeman kept a watch for possible obstructions and took the necessary action before the rope suffered surface embrittlement. 161

Rope man's handbook Haulage ropes

Damage y

Sometimes a haulage rope is accidentally damaged. Slack rope

If slack rope forms so that a coil or coils fall over the side of the drum and are pulled tight before being noticed, wires are likely to be damaged and sheared at that part which has contacted the drum flange (Fig 82). Damage of this type should not be ignored but should be carefully examined by a competent person to decide the appropriate action to be taken. Run overs

If a rope has been accidentally runover by tubs it can be severely crushed and some wires may be partially or completely cut through (or sheared, Fig 43k). Again, such damage should not be ignored otherwise the rope is likely to break at the affected part in subsequent service. Trapping

A rope may become securely trapped by some obstruction or under a fall, on a single occasion, and broken by the resulting overload. The rope will show typical tensile fractures (Fig 43c) at the wire ends but, probably, no other useful evidence. However, some ropes are known by their ropemen to become partially trapped on many occasions but, because they free themselves as the tubs approach the trap, no action is taken to rectify matters. This is dangerous, because such ropes are almost certain to break eventually. A rope which is repeatedly trapped by an obstruction is likely to cut a groove in the obstruction and eventually be unable to free itself when the groove becomes too deep. Examples of repeated trapping are where ropes repeatedly get on the wrong side of a guide rail, or behind a large bolt head or nut, or in the gap in the rails at a crossing or parting. Consider the last example. When a rope runs in the gap in the rails (Fig83) it will be pulled free as the tubs approach on all occasions until the rope has undercut the top flange of the rail so deeply that it will be unable to free itself; if the track is not pulled up by the rope, then the rope itself must break. The broken end of the rope will show many wire fractures of the tension type, because the rope has been overloaded on a single occasion, and some wires may show sheared or partly sheared ends if the rope was pulled hard against a sharp edge of the rail end. On the leading side of the rope fracture one side of the rope surface will probably show a succession of bruises or bind marks spaced at decreasing intervals as the fracture is approached and with the final mark at the fracture; these are the points at which the rope successively became seized in the gap with increasing force during the final occasion on which it was trapped. A crossing designed to prevent this type of damage is shown in Fig 84. 162

(a) Possible cause of damage to rope at Y through coils falling over side of drum (b) Samples arranged to show tightening coil at X and point of damage and eventual fracture at Y

Figure 82.

Failure of haulage rope as result of earlier damage

163

Haulage ropes

Ropeman's handbook

Maintenance of haulage ropes

Haulage ropes, whether galvanised or ungalvanised, should be kept well lubricated. The various types of lubricant available and methods of application have been discussed in Chapter 3. Galvanised ropes should be used when conditions are corrosive.

Figure 83.

Haulage rope trapped in rails

No ropemaker can supply a haulage rope guaranteed to stand up to heavy wear (requiring large outer wires) and at the same time to work satisfactorily around small drums and pulleys (requiring small outer wires for flexibility). It is usually faults in the working conditions that lead to unsatisfactory rope service. The aim should be to avoid all unnecessary bends in the rope; where the road turns, the rope should be guided smoothly around the bend on large wheels or on arcs of smaller wall pulleys. If a rope has to change direction through a large angle around a single pulley or wheel, it is good practice, in order to increase rope life, to use a pulley or wheel having as large a diameter as possible, preferably at least 48 times the rope diameter (see BS 4878:1973 and NCB Specification 601/1972). This is important if the rope changes direction by more than about 10 degrees at any one pulley. If the change of direction is less than 10 degrees, the stress caused by bending is low. That is why the diameters of road rollers and the rollers forming arcs of wall pulleys can be small. A roller or wheel which produces a large change in direction should be of a suitable diameter. Ropes should be prevented from rubbing against roof girders, arch legs, seized rollers, rails, rerailers, and other obstructions- particularly metal ones. (Such rubbing will cause wear and is very likely to cause surface embrittlement.) Ropes should not be allowed to run in the gaps in rails or other potential traps (danger of overloads), nor should they bear against the revolving axles of tubs in undertub haulage (local wear). Badly designed or worn surge pads or segments on the driving wheel of an endless haulage may cause plucking or uneven surging of the rope (leading to wear and perhaps fatigue). Irregular coiling on the drum may cause local deformations in the rope (leading to rapid local wear). Such bad coiling on a drum, due to flapping of the incoming rope, may often be corrected by mounting a pulley directly in front of the drum so that the pulley is free to move along a long shaft extending across the whole width of the drum; the flapping of the rope will then be damped or suppressed by the pulley before it reaches the drum. Kinking leads to similar deformations.

Figure 84.

Type of rail crossing designed to reduce trapping ofthe rope to a minimum

A badly designed brake on a drum may heat the drum flange {rom the normal temperature of about 60°F (15°C) to a temperature such that the hand cannot be held continuously against the flange (above 150°F or 65°C), in which case the lubricant in the coils of rope lying against that flange will become very fluid and will run out of the rope (and lead to corrosion). 165

Ropeman '.11 handbook

Anything that the ropeman can do, or get do":e, to correct such working conditions will improve the performance of hiS ropes.

Appendix 1

Thus the ideal conditions for a haulage rope are: a large drum or surge whee\, a steady or smooth haul, a straight road which is either level or with the same slope throughout, a rope running true between the rails on well-maintained and free-running rollers mounted m pockets clear of water , and no obstructions or water elsewhere in the path of the rope.

A method of determining the minimum rope breaking strength for a direct haulage system

When to discard a haulage rope The limits of deterioration which apply to haulage ropes are discussed in detail in Chapter 6 and summarised for all ropes m Appendix 2.

The tension in the haulage rope on an incline is due to two rna jor factors, o the gravitational pull on the load and on the total weight of rope in the system,

o the frictional resistances to motion of the load and the rope. The gravitational force is dependent upon the gradient; the steeper the incline, the higher is the tension in the rope. For accurate calculations, the sine of the angle of gradient must be taken into account, but for all practical purposes, the ratio of vertical rise to horizontal travel need only be considered. Vehicle friction can be taken as 1 per cent of the weight of the vehicle plus contents for vehicles having rolling hearings and as 2 per cent of the weight of vehicle plus contents for vehicles having plain bearings. Rope friction can be taken as 10 per cent of the total weight of the rope. Additional loads are imposed on the rope due to: - the system being accelerated and - the rope tension arrangement of endless rope haulages and - bending the rope around deflecting pulleys and sheaves. The maximum working tension, multiplied by the safety factor, gives the rope breaking strength required to deal with that working tension. The safety factor is intended to take care of the extra tensions in the wires caused by sudden changes in speed, or jerking of the rope, bending of the rope around pulleys, etc. The value of the factor varies with the type of haulage. Direct haulage of mineral and material involves more starting and stopping of the rope (ie many repeated shock loads) and a safety factor of at least five is normally used. Endless haulage is generally smooth-running (ie few shock loads) and a slightly lower safety factor may sometimes be employed. However, the Engineer will probably calculate the rope strength required to produce a suitable safety factor by employing the formula reproduced overleaf.

166

167

Ropeman 's handbook

In order to determine the minimum required breaking strength of a direct haulage rope the following formula may be used. If S =minimum required breaking strength of the rope (kgf) F =factor of safety W = total weight of vehicles and contents (kg) w =total weight of the line rope (kg) e = maximum angle of inclination of the roadway (degrees) ex = average angle of inclination of the roadway (degrees) fJ., = vehicle friction J.Lr = rope friction g =acceleration due to gravity (ie 9.81 m/s') . a =maximum rate of acceleratiOn or deceleratiOn of the haulag system (m/s')

Then:

S=F[ w(~+sin IJ )+w(~+sin a )+W,u,+w.u,] or S=F[ w(~+sin O+,u, )+w(~+sin a+.u,)] Where a is not known .:!. can be assumed to be 0.125 for all reasonable a 0 service conditions. In the case of main and tail and endless rope ha-ulage systems the formula becomes more involved and the Colliery Engineer will normally calculate the minimum breaking strength required of the rope.

Appendix 2 When to discard a rope As a general rule no rope should remain in service: D

When the Engineer considers that the factor of safety has become too low (when the reserve of strength is no longer sufficient to ensure that the rope can safely withstand the repeated shock loads. bends. etc).

o When the loss in rope strength due to wear, corrosion, or both is approaching one-sixth or 16 per cent of the original strength (or any lesser value set by the Engineer). D When the loss in rope strength due to fatigue, corrosion-fatigue, or surface embrittlement, or due to cracked or broken wires of any kind, is approaching one-tenth or 10 per cent of the original strength (or any lesser value set by the Engineer). The loss in strength may be estimated by regarding all broken or cracked wires within a length of two rope lays as no longer contributing any strength to that part of the rope. · D

When the outer wires have lost about one-third or 33 per cent of their depth as a result of any form of deterioration.

o When the outer wires are becoming loose and displaced for any reason. o When the rope has become kinked or otherwise deformed, distorted, or damaged, and the affected part cannot be cut out. D

When the rope has been subjected to a severe overwind or overload, or to severe shock loading, as a result of an accident.

o When examination of the rope leaves any doubt as to its safety on any grounds. D

168

When a rope, which is still in good condition, rcachc~ the- maximum statutory life for its type, as laid down in Regulations, or the maximum life specified by the Engineer.

169

Bibliography

BIBLIOGRAPHY

List of regulations, specifications and official publications dealing with ropes

NCB Specifications

NCB Spec No 175/1968 NCB Spec No 176/1968 WSire Ropes_for Mineral Haulage and Manrid' otranded Wire Ropes for w· d. m'='. NCB Spec No 186/1970 Lock d eo·1 In mg. 1 Winding Ropes. e NCB Spec No 353/1966 Sockets, pins and zi colliery haulage r~pe~~ cone and tml strand units for NCB Spec No 366/1968 Round Strand Wire Ropes for Mine NCB Spec No 367/1968

~f::~~;~~fo~n~~~i~~~sulfor ~e!!~1;;~~ge.

Regulations The Law relating to Safety and Health in Mines and Quarries, Part 2, Section BThe Coal and Other Mines (Shafts, Outlets and Roads) Regulations, 1960. Reg 17(1) Use of spliced ropes. 17(2) Maximum statutory life of ropes (shaft 3! years) (staple pit 3,\ years) ( unwalkable outlet 2,\ years) 17(3) Minimum factor of safety (winding rope 6!). 18 and 19 Examination and maintenance of ropes and attachments. 65 to 70 Capping, recapping, and examination of recapping samples.

NCB Spec No 368/1968 NCB Spec No 386/1968 W' R '=' a age. Ire opes 1or use with Coal Curt d Face Machinery. ers an other Coal NCB Spec No 388/1970 H If NCB Spec No 461/1965 a -locked Coil Guide Ropes Sockets (BS 463 Pattern) f Haulage and General E . or . rre Ropes for Colliery NCB Spec No 465/1 965 ngmeenn• Purpos NCB Spec No 483/1970 Soc~ets for use with White MetatCa in es. White Capping Metal for Steel Wire l'fop~: Note· The latest · ,, . versrons OJ these standards and s ]ic . The dates given here are co"ect at th ti pee~~ a~ons should always be used. e me OJ gomg to press.

w·

Special regulations (friction winding) A set of special regulations is issued for each colliery concerned and includes regulations concerning capping, examination of any recapping samples, etc; they are normally uniform in all cases as regards certain aspects such as maximum statutory life of rope (winding ropes two years, balance ropes three yearS). Specifications

British Standards BS 236:1968

Stranded Wire Ropes for Mine Hoisting (Winding) Purposes. BS 302:1968 Steel Wire Ropes for Cranes, Excavators and General Engineering Purposes. BS 330:1968 Stranded Wire Ropes for Haulage Purposes. Galvanised Coatings on Wire. BS 443:1969 BS 463 Part 1:1958 Drop-forged Sockets for Wire Ropes for General Engine@Fing Purposes. BS 463 Part 2:1970 (Metric Units) Sockets for Wire Ropes. BS 525:1973 Fibre Cores for Wire Ropes. BS 643:1970 White Metal Ingots for Capping Steel Wir.e Ropes. BS 2763:1968 Round Steel Wire for Ropes. BS 2772 Part 2: 1977 Iron and Steel for Colliery Haulage and Winding Equipment: Wrought Steel. BS 3436:1961 Ingot Zinc.

170 171

Index

Index Where a subject is discussed on more than one ~age, . a page number in bold type indicates the main drscussron.

Abrasive wear, 81, 119 Additives to rope lubricants, 45, 120

Balance rope loop control, 131-132 Balance ropes, 49,129-137 Bearing surface of rope, 80, 95 Bending primary, 88

secondary, 75,88-92,98,116,121,137 Bending test for wires, 75 Birdcage distortion, 101, 122 Breakages due to wear, 82-83 Breaking strength, 88, 122, 149, 167 British Standards list of, 170 302 general engineering, 17 330 haulage ropes, 149 443 zinc coatings, 25 463 sockets, 67, 151 525 fibre core, 13 643 capping metal, 57, 63 2763 rope wire, 10, 25 2772 wrought steel, 57 Brittleness of wires, 10, 96 Broken wires, 60, 72, 96, 97 Brush, rope, 56, 60, 63 Buried wire serving, 32 Calcium chloride, 149 Caliper, 70, 72 Cappings deterioration at, 60, 126 for balance ropes, 132-133 for haulage ropes, 66-69, 149-151 for windingropes,52-66, 108,115,121, 126 inserted cone, 66-69 wedge, 62-66, 108, 121, 126, 140-142 white metal, 51, 52-62, 108, 121, 140 Chain pitting, 97 Chatter (of loose wires), 74 Chisel-end fractures, 84, 159 Clamps, 52, 59, 63, 109, 142, 153 Oeaning of ropes, 47, 72, 115, 127, 144, 153

172

Qeaning of wires during capping, 56, 63 Coiling irregular, 99 on drum, 29 Cold work, 96 Cone and tail, 66-69, 150-151 Cores strand, 11-12 rope, 13-14, 16, 17 Cork screwing {distortion), 99-102 Corrosion general, 75, 84, 109, 119-120, 134-135, 147, 156 at damaged part, 98 at martensitic cracks, rn external, 72, 86, 109, 145 fractures, 88 internal, 73, 82, 87, 109, 116 prevention of, 119-120, 123 scale, 75, 116, 144 Corrosion-fatigue general, 86, 88, 94, 122 fractures, 94 prevention of, 94, 122, 125, 156 Cracks fatigue, 92 surface embrittlement, 95 Crossed tuck, 41 Cutting of ropes, 54 Damage and distortion, 72, 98-102, 122, 125, 134-136, 162-164 Deformation, 98-103, 136 Depth of wire, 82 Deterioration balance ropes, 134-137 cappings, 60-61, 126 damaged part, 98, 102, 136 guide ropes, 147 haulage ropes, 154-164 winding ropes, 114, 118-126 Diameters, drums and pulleys, 118, 119, 121 Discard of ropes, 102-103, 138, 148, 166, 169 Distortion of ropes, 72, 99-102, 122, 125

Drawn-galvanised finish, 25 Drum attachment of rope to, 29-30 diameter, 18, 119, 121 surface irregularities of, 118 Drum brakes, 165 Drum-winding ropes deterioration of, 115 factor of safety of, 104-106 lubrication of, 46-49 Ductility of wire, 10, 96

Feeler gauges, 72 Filler Seale lay, 22 Finish, surface, 23, 120 Fins, formation of, 80, 95 Flat ropes, 17, 24, 129, 136 Flat strands, 13 Fleet angle, 119, 122 F1exibility of equal lay ropes, 23 fiat ropes, 17, 24, 129 guide and rubbing ropes, 139 locked coil ropes, 17, 24 multi-strand ropes, 16, 24, 129 Echelon fractures, 159 strands, 12 Edge-pitting, 86 triangular-strand ropes, 16, 24 Elbow-shaped bends, 99, 158 Flexible ropes, 80, 129, 156, 158 Electro-galvanising, 25 Embrittlement, 73, YS-Y.S, 125-126, 160- Flexion fractures, 83, 86 Fractures 161 at damage and distortion 102 Equal lay, 22 at kink, 102 ' Examination bending {flexion), 83, 86 at testing centres, 76-78, 103, 108, 116 chisel-end, 84 balance ropes, 133, 137 corrosion, 88 daily, 114 corrosion-fatigue, 94 external, 73, 133, 144, 152 echelon, 159 guide ropes, 144 fatigue, 92 haulage ropes, 152-153 fiexion, 83, 86 internal, 74 stepped, 98 locked coil, 74 surface embrittlement, 96-98 recarping samples, 109 tensile, 77, 88 speCial, 114-116 wear, 84 winding ropes, 113-117 Friction-winding ropes Extension of statutory life, 127 general, 110-113, 129 Eye-glass, 70, 75 deterioration of, 115 factor of safety of, 110-111 lubrication, 49, 119-120 Factor of safety recapping, 110 dtum-winder ropes, 104-106 regulations, 110, 128 friction-winder ropes, 110-111 tensions in, 111-113 guide ropes, 139 Full-lock wires, 11, 17 haulage ropes, 149, 167 Fatigue general, 88, 121 at ~pping;60, 121, 126, 143, 147 Galvanised ropes, 23-25, 89, 120, 122, at kmk, 102 139, 156 at surface irregularities, 95, 97 Gland, wedge-type, 110, 140-142 cracks, 75 Grooved cones, 67, 150 due to damage, 98, 102, 134-130 Grooves due to martensitic embrittlernent, 96 in internal wires, 81 fractures, 92, 116 pulley, 108, 122 limit, 88 Guide ropes prevention of, 88, 121-122 general, 139-148 secondary bending, 75, 89-92, 98, 116 half-locked, 19, 139 121 , lubrication, 50

173

Index

Ropeman 's handbook

Guide ropes ( contd.) tensioning of, 139, 142-143 wire for, 10 Guides, rigid, alignment, 122 Half-locked guide ropes, 19, 139 Half-lock wires, 11 Hammer ropeman's, 72 -test, 74, 116 Haulage ropes, capping, 66, 149-151 care of, 50 choice of, 149 damage to, 162-164 deterioration of, 154-164 examination of, 152-153 installation of, 149 loads on, 167 lubrication oL 50, 105 minimum breaking strength of, 167 recapping; 151 records of, 153 safety factor of, 149, 167 splicing, 3S-43, 160-161 when to discard, 102-103, 169 working tension in, 167 Hernia distortion, 101, 122 Hot-dip galvanising, 25 Inserted-rone cappings, 66-69, 150-151 Installation of balance ropes, 129-132 guide ropes, 139-144 haulage ropes, '149 winding ropes, 106-108 Instruments and tools, ropeman's, 31, 40, 70 Kinking, 99, 152, 156-160 Lang's lay, 19 Lay

change in length of, 99 equal, 22 filler Seale, 22 Lang's, 19 left-hand, 19, 29 length of, 21 looseness of, 72, 89, 107

174

Lay ( contd.) measurement of, 72 ordinary, 19 right-hand, 19, 29 Seale, 22 shortening of (at kink), 99 types of, 19 Warrington, 22 Life, rope, 127-128 Loads general, 140 on haulage ropes, 167 on winding ropes, 105-106 shock, 105, 121, 167 Locked-coil ropes general, 17, 24, 54 distortion of, 99-102 examination of, 74 lubrication, 45, 47 Locked tuck, 41 Long splice, 36 Lubrication after capping, 51 general, 14, 25, 44-S1, 72, 119, 127 of balance ropes, 49, 137 of drum-winding ropes;46-49, 119,122, 127 of friction-winding ropes, 49, 119-120, 122 of guide ropes, SO, 144, 147 of haulage ropes, SO, 165 Lubricator, pressure, 47

Maintenance of balance ropes, 137 guide and rubbing ropes, 147-148 haulage ropes, 165-166 winding ropes, 127 Martensite, 96 Martensitic embrittlcment. 73,96-97, 125126, 160-161 Measurement of diameter and lay, 72, 116, 145 Micrometer, wire, 70 Multi-rope friction winders, 111-113 Multi-strand ropes, 16, 24, 129 NCB Specifications list of, 171 186locked coil ropes, 19, 104 353 sockets, zinc cone & tail, 67, 151 388 half-locked coil guide ropes, 19, 139

NCB Spe9.:(ications (contd.L 461 sockets, etc (BS463 pattern), 67, 151 465 sockets for white metal cappings, 54,60 483 white capping metal, 57, 63 Necking, 77, 84 Nicking, 81, 116 Non-destructive testing, 79 Non-rotating ropes, 16, 24, 129 Ordinary lay, 19 Ordinary serving, 32 Oval strands, i3 Parallel tuck, 41 Parking positions, 119 Paying out haulage rope, 149 winding rope, 107 Penknife, 70 Permanent bends, 98-99, 134, 144, 156 Fitch of rope, 21 Pitting, 70, 75, 86 Pitting, chain, 97 Plastic wear, 73, 80, 95-96, 160 Postformed ropes, 23 Preformed ropes, 23 Preheating temperatures, 57 Pressure lubricator, 47 Primary bending; 88 Protection, rising loop, 132 Pulley diameter, 18, 119, 121 grooves, 108, 122 Recapping haulage ropes, 151 samples, examination of, 74; 114, 152 winding ropes, 108-110 Record book, 117, 145, 153 Recovery of sockets, 62, 152 Reddies, 17 Reference sample, 108, 153 Regulation 17 (2), 127 17 (3), 106 19, 114, 115 65 and 67, 108, 114, 151 for friction-winders, 110, 128, 138 Reverse bend test, 78 Rigid guides, alignment of, 122

Rods, 19 Rollers, roadway, 156 Rope centring clamp, 57 Ropelets, 17, 136 Rope loop control, balance, 131-132 Rotation of ropes, 100-101, 107, 140 Round strand ropes, 14, 24, 149 Round strands, 12 Rotind wires, 11 Rubbing ropes, 19, 139 Run-overs, 102, 162 Rust inhibitors, 120 Safety blocks, 62, 63, 117 Safety clamps, 142 Safety factor, 88, 104-106, 110-111, 139, 149, 167 Safety ropes, 153 Scriber, 70, 75 Scuffed nicks, 81 Seale lay, 22 Secondary bending, 75,88,89-92,98,116, 121, 137 Serving (seizing), 30-35, 52, 109, 152 Serving mallets, 31 Serving wire, 31 Shock loads, 105, 109, 121-122, 167 Side-by-side tuck, 41 Slack rope kinking due to, 99, 154, 156 protection, 110 shocks due to, 122 Sleeve, guide rope, 143 Snarling, 129, 137 Sockets, 52; 54; 67, 108 Soldered servings, 34 Special examination, 114-116, 153 Specifications, BS, NCB (list of), 170-171 Splicing, general, 35-43, 152, 153, 160, 161 tools, 40 Static loads, 106 Statutory examinations, 113-117 Statutory life, extension of, 127 Stepped fractilres, 9& Stitching, flat rope, 17, 136 Storage of ropes, 26 Stranded ropes general, 13 multi-strand, 16 round strand, 14 triangular strand, 16 Strands, 11

175

Ropeman 's handbook

Strength of rope aggregate, 76 breaking, 76, 88, 122 loss of, 102-103 Surface finish, 23, 120 irregularities, 95, 97 , embrittlement, 73, 95-98, 160-161 Suspended loads, 105-106 Swivels, 129 Tail or balance ropes, 129-137 Taper of socket, 60 Temperatures socket, 57 white metal, 58, 63 Tens1le strength general, 10 of guide ropes, 10 of haulage ropes, 149 of winding ropes, 104 Tension fractures, 77, 88 in guide ropes, 139, 142-143 maximum working, 167 rope, 88, 111-113 test, 76 Test at testing centre, 76-78, 103, 108, 116 hammer, 74 non-destructive, 79 reverse bend, 78 tensile, 76 torsion, 78 Tools and instruments, 31, 40, 70-72 Torsion test, 78 Trammel, rope lay, 72, 73 Trapping, 162-164 Triangular strands, 13 strand ropes, 16, 24, 149 wires, 11 TUcking, 36, 39-43, 160 Twisting, 100-101, 107, 129, 137

Uncoiling and unreeling, 27-28, 107, 149 Ungalvanised finish, 25 Waisting, 77, 84 Warrington lay, 22 Water displacers and repellents, 44, 46, 120

176

Wave form, of wire, 75-76 Waviness, 72, 99-102, 122 Wear abrasive, 81, 118, 156 at kink, 102, 156-160 external, 73, SO, 107, 109, 134-135 fractures, 84 in guide ropes, 145-147 in haulage ropes, 156-160 internal, 21, 74, 81, 87, 90, 109, 116 inwindingropes, 107,109, 116,ll8-119 plastic, 73, 81, 95, 119, 160 prevention of, 118, 123 Wedge gland, self-tightening, 110, 140142 Wedge-type cappings, 62-66 White metal cappings, 52-62 Width of wire, 82 Winding ropes capping, 52-66, 108 care of, 46-49 choice of, 104-105 deterioration of, 118-126 discarding of, 102-103, 169 examination of, 113-117 factor of safety, 104-106 installation of, 106-108 recapping, 108-110 reference sample, 108 wear on, 118-119 Winding shocks, 109 Wiped serving, 34 Wire crown of, 76 depth, 82 drawing, 10, 96 micrometer, 70 serving, 31 shapes, 11 tensile strength, 10 used in haulage ropes, 149 used in winding ropes, 104 width, 82 Wires brittleness of, 10 broken, 60, 72, 116, 139 displaced, 72, 83-84 looseness of, 74, 82, 87, 116 Working tension, maximum, 149

Zinc coating, 23-25, 120, 139 Zinc cone cappings, 66-69, 150-151