Basic Hydraulic: Hands-on Training

Hands-on Training

Basic Hydraulic Hydraulic Components(3) Valve

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Basic Hydraulic

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Contents

Topic 1. Kind of control valve 2. Directional control valve 3. Pressure control valve 4. Flow control valve

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Basic Hydraulic

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1. Kind of control valve

Directional control valve

Control valve

Pressure control valve

Flow control valve

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Basic Hydraulic

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Introduction Directional Control Valves. Directional Control Valves provide links between various parts of the hydraulic system, by connecting of disconnecting and/or changing the oil flow direction.

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DCV Designation

P =

T= A&B=

Pressure Port.

Return (Tank) Port. Actuator Ports.

Designation: The number of ports and the number of valve positions that a DCV has will be the basic to describe the type of valve designation Hydraulic Components

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Actuation of Spools. The spools are moved and controlled by different methods of actuation. Manually operated

Hand lever with detent

Roller tappet

Pedal

Hydraulic

Pneumatic operated Solenoid operated Spring return, solenoid operated

Spring centered, solenoid Operated Pilot operated, Electrical controlled

operated

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Spools Metering Notches

Grooves

What is the function of Grooves? 1. Hold a small amount of oil for lubrication between body and spool. 2. Assists with sealing. 3. Retains small particles of contamination. What is the function of Metering Notches? 1. Minimizes the possibility of hydraulic lock up. 2. Better control of flow rates with fine operation and cushioning. Hydraulic Components

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2. Directional control valve 1) What is the Kinds of directional control valve? Open center valve

Closed center valve Open center

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Closed center

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2. Directional control valve 2) Open center control valve structure 3- Valve 1- jet sensor 2-Jet sensor orifice relief valvebody

4- Spool

5- Return spring

8- Safety suction valve

6- Main Relief valve Hydraulic Components

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7- Suction valve

9- Check Valve

2. Directional control valve 3) Open center control valve operation Which direction cylinder will move refer to the Spool position in each picture? Neutral

Spool moves to left Oil goes to cylinder bottom side

Spool moves to right Oil goes to cylinder head side

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2. Directional control valve 4) Closed center control valve structure 1/2 1- Unload Valve

2- Cover

3-Main Relief valve 4- Return spring 5- Spool 6- Valve Body

High Pressure Line From pump (RED)

Low Pressure Line from Drain to tank (BLUE)

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7- Cover Basic Hydraulic

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2. Directional control valve 4) Closed center control valve structure 2/2 2- LS shuttle valve 3- Pressure Compensation valve To Actuator “A” port

To Actuator “B” port

1- Load Check Valve

Return to Tank (Blue)

5- Valve Body Hydraulic Components

From pump (RED) Basic Hydraulic

4 – Safety suction Valve Page 12/25

3. Pressure control valve 1) Kinds of pressure control valve

Relief valve

Unload valve Pressure control valve Suction valve

Reducing valve

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3. Pressure control valve 2) Kinds of relief valve Ball type Direct acting type

Poppet type Spool type

Relief valve

Piston type Differential pressure type Single stage Pilot type Two stage

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3. Pressure control valve 3) Relief valve structure 4- Sleeve

2-Pilot poppet Valve seat

1- Pilot Poppet

3- Pilot poppet Spring

5 - Holder

6-Retianer

7- Main Relief Valve Seat

9-Main Relief Valve spring

8-Main Relief Valve Piston Hydraulic Components

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Main Relief Valves

Two Stage Relief Valve

What is the function of Main Relief Valve?

Single Stage Relief Valve

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The Main Relief Valve is designed to maintain a maximum working pressure. When the hydraulic oil reaches maximum pressure the relief valve will allow the flow to return to tank, protecting all hydraulic components.

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3. Pressure control valve 4) Relief valve operation

d1

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3. Pressure control valve 5) Unload valve structure 1-Holder

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2-Spring

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3-Spool

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3. Pressure control valve 6) Unload valve operation LS circuit

b

Neutral Pump circuit c a

Tank circuit LS circuit

Working

Pump circuit

Tank circuit Hydraulic Components

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3. Pressure control valve 7) Suction valve structure 2- Spring 1-Valve Body

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3- Poppet

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4- Valve Seat

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3. Pressure control valve 8) Suction valve operation Tank circuit

Actuator circuit

Tank circuit

Actuator circuit

Normal

Suction

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Safety Suction Valve To Tank

Relief of high pressure

The safety suction valve is to protect the hydraulic circuit when the actuator generates its own From Actuator pressure. (eg. When a hydraulic cylinder is pushed by an external force) The Safety Suction Valve is to relief positive pressure. From Tank

When negative pressure is generated the Safety Suction Valve will open up and allow oil to flow in from the hydraulic reservoir stopping excessive negative pressure. Hydraulic Components

To Actuator

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3. Pressure control valve 9) Reducing valve structure

Self Pressure Reducing valve

8- Spring 7- Sleeve

1- Valve body

2- Spool

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3- Spring

4-Poppet

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5-Holder Page 23/25

6- Spring

3. Pressure control valve 11) PPC valve structure Pilot-pressure Proportional Control 6-Nut 7- Joint 5-Disc

4-Piston

8- Plate 9- Retainer

3-Centering spring 2- Metering spring

1-Spool

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10- Valve body

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3. Pressure control valve 12) PPC valve operation

f1

f2

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