568 Forest Machine Hydraulic System Relief Valve (Line) - Test and Adjust Caterpillar


Relief Valve (Line) - Test and Adjust
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1.1. Introduction
2.1. Required Tools
3.1. Machine Preparation
4.2. Temporary Setting of the Main Relief Valve
5.1. Test Procedure
6.1. Boom Cylinders
7.2. Adjustment (Boom Cylinder Head End)
8.3. Drift Reduction Valve
9.2. Adjustment (Boom Cylinder Rod End)
10.1. Stick Cylinder
11.2. Adjustment (Stick Cylinder Head End)
12.2. Adjustment (Stick Cylinder Rod End)
13.3. Drift Reduction Valve
14.1. Bucket / Heel / Tilt Cylinder
15.2. Adjustment (Cylinder Head End)
16.2. Adjustment (Cylinder Rod End)
17.1. Thumb Cylinder
18.2. Adjustment (Cylinder Head End)
19.2. Adjustment (Cylinder Rod End)
20.1. Worksheet

Introduction

The line relief valves are located between each cylinder and the respective control valve. The line relief valve limits the overload pressures that can be created in the implement cylinders. The line relief valves are located on the left side and right side of the main control valve. The line relief valves are accessible from above the main control valve and below the machine after removal of the access plate.



Illustration 1g02068598
Line relief valve
(L) Locknut
(A) Adjustment screw

Required Tools



Illustration 2g01623868
Tooling group "B"
198-4240 Digital Pressure Indicator Gp

Table 1
Tool  Item  Part Number  Description  Qty 
198-4240  Digital Pressure Indicator Gp   
  B1  198-4234  Indicator 
B2 198-4238  Pressure Sensor 34,450 kPa (5,000 psi) 
B3 198-4239  Pressure Sensor 41,368 kPa (6,000 psi) 
B4 198-4236  Extension Cable 

Machine Preparation

  1. Position the machine on level ground and stop the engine.

  2. Release the pressure in the hydraulic system. Refer to Testing and Adjusting, "System Pressure - Release".


    Illustration 3g02068357
    Pump compartment
    (1) Pressure tap (delivery pressure for drive pump)
    (2) Pressure tap (delivery pressure for idler pump)
    (3) Pressure tap (power shift pressure)

  3. Attach both 41,368 kPa (6,000 psi) pressure sensors to pressure tap (1) and pressure tap (2).

  4. Connect a 34,450 kPa (5,000 psi) pressure sensor to pressure tap (3) to monitor power shift pressure.

Temporary Setting of the Main Relief Valve

  1. A temporary setting of the main relief valve is required before any line relief valves can be adjusted.

  2. Move the joystick for the bucket until the boom is at the full BOOM RAISE position (full extension of boom cylinder).

  3. Check the main relief valve pressure setting at pressure tap (1) or pressure tap (2).

  4. Be sure that the main relief valve pressure is set at the pressure specification. Refer to Table 2.

    Note: Always make final pressure adjustments on pressure rise.



    Illustration 4g02102305
    Main relief valve (standard)
    (A) Adjustment screw
    (L) Locknut


    Illustration 5g02102306
    Main relief valve (heavy lift)
    (A) Adjustment screw
    (L) Locknut

  5. Loosen the locknut. Turn the adjustment screw clockwise for one half turn. Tighten the locknut.

  6. Reset main relief valve pressure setting to the normal operating condition after the completion of the line relief test and adjust. Refer to Testing and Adjusting, "Relief Valve (Main) - Test and Adjust".

Test Procedure

  1. Start the engine.

  2. Increase the hydraulic oil temperature to 50° ± 10°C (122° ± 18°F).

  3. Place the machine controls at the following settings: engine speed dial "2" and AEC switch OFF.

  4. Enter the service mode.

    1. Input the password "9992".

    2. Select "Override Parameters".


    Illustration 6g02794459

  5. Set the power shift pressure to the specification. Refer to Table 2 for the pressure specification. Confirm the power shift pressure setting at pressure tap (3).

  6. Operate the implement joystick in the appropriate direction in order to relieve the valve.

    Note: A continuous relief of the valve for more than 10 seconds is not allowed.

  7. Check the main relief valve pressure setting at pressure tap (1) or pressure tap (2). Refer to Table 2 for the pressure specifications of the line relief valves.

  8. Return the joystick to the NEUTRAL position.

Boom Cylinders

Adjustment (Boom Cylinder Head End)

Drift Reduction Valve



Illustration 7g02079173
Line relief valve on the drift reduction valve for the boom cylinder head end

  1. Move the joystick for the boom to the full BOOM RAISE position. Hold the joystick for the boom in this position and check the pressure gauge reading at pressure tap (1).

  2. Return the joystick for the boom to the NEUTRAL position.

  3. The pressure reading should be within the specification. Refer to Table 2. If the pressure reading at pressure tap (1) is not within the specification, adjust the line relief valve that is on the drift reduction valve.

  4. In order to adjust the line relief valve, loosen the locknut and turn the adjustment screw until the pressure reading at pressure tap (1) is within the specification. Refer to Table 2.

    Note: Turn the adjustment screw clockwise in order to increase the pressure. Turn the adjustment screw counterclockwise in order to decrease the pressure.

    Note: Always make final pressure adjustment on pressure rise.

  5. Tighten the locknut on the line relief valve.

Adjustment (Boom Cylinder Rod End)



    Illustration 8g02102178
    Line relief valve for the boom cylinder rod end

    Note: In order to adjust the line relief valve pressure setting for the boom cylinder rod end, a temporary adjustment of the line relief valve for the bucket cylinder rod end must be performed. The line relief valve for the bucket cylinder rod end is located right above the line relief valve for the boom cylinder rod end on the main control valve.

  1. Loosen the locknut on the line relief valve for the bucket cylinder rod end. Turn the adjustment screw by one quarter turn in a clockwise direction. Tighten the locknut on the line relief valve for the bucket cylinder rod end.

  2. Move the joystick for the bucket to the full BUCKET OPEN position. Hold the joystick for the bucket in this position. At the same time, move the joystick for the boom until the boom is at the full BOOM DOWN position (full retraction of boom cylinders). Hold the joystick for the boom in this position.

  3. Check the pressure reading for the boom cylinder rod end at pressure tap (1).

  4. Return the joystick to the NEUTRAL position.

  5. The pressure reading should be within the specification. Refer to Table 2. If the pressure reading at pressure tap (1) is not within the specification, adjust the line relief valve for the boom cylinder rod ends.

  6. Loosen the locknut on the line relief valve for the boom cylinder rod end. Turn the adjustment screw until the pressure reading at pressure tap (1) is within the specification. Refer to Table 2.

    Note: Turn the adjustment screw clockwise in order to increase the pressure. Turn the adjustment screw counterclockwise in order to decrease the pressure.

    Note: Always make final pressure adjustment on pressure rise.

  7. Tighten the locknut on the line relief valve.

  8. After completion of line relief valve adjustment for the boom cylinders, return the line relief valve pressure setting of the line relief valve for the bucket cylinder rod end to the specified pressure setting. Refer to Table 2.

Note: If an appropriate location is not available to fully extend the boom cylinders, exchange the functions of the boom line relief valves. Remove the line relief valve for the boom cylinder head end and the line relief valve for the boom cylinder rod end from the main control valve. Exchange the location of the line relief valves. Adjust the pressure of the boom line relief valve that is now attached in the head end. After completion of line relief valve adjustment, return the respective line relief valves to the original locations.

Stick Cylinder

Adjustment (Stick Cylinder Head End)



    Illustration 9g02102218
    Line relief valve for the stick cylinder head end

  1. To adjust the line relief valve pressure setting of the stick cylinder head end, move the joystick for the stick until the stick is at the full STICK IN position (full extension of stick cylinder). Hold the joystick for the stick in this position.

  2. Check the pressure reading for the stick cylinder head end at pressure tap (2).

  3. Return the joystick for the stick to the NEUTRAL position.

  4. The pressure reading should be within the specification. Refer to Table 2. If the pressure reading at pressure tap (2) is not within the specification, adjust the line relief valve for the stick cylinder head end.

  5. In order to adjust the line relief valve, loosen the locknut and turn the adjustment screw until the pressure reading at pressure tap (2) is within the specification. Refer to Table 2.

    Note: Turn the adjustment screw clockwise in order to increase the pressure. Turn the adjustment screw counterclockwise in order to decrease the pressure.

    Note: Always make final pressure adjustment on pressure rise.

  6. Tighten the locknut on the line relief valve.

Adjustment (Stick Cylinder Rod End)

Drift Reduction Valve



Illustration 10g02078993
Line relief valve on the drift reduction valve for the stick cylinder rod end

  1. To adjust the line relief valve pressure setting of the stick cylinder rod end, move the joystick for the stick until the stick is at the full STICK OUT position (full retraction of stick cylinder). Hold the joystick for the stick in this position.

  2. Check the pressure reading in the stick cylinder rod end at pressure tap (2).

  3. Return the joystick for the stick to the NEUTRAL position.

  4. The pressure reading should be within the specification. Refer to Table 2. If the pressure reading at pressure tap (2) is not within the specification, adjust the line relief valve that is on the drift reduction valve.

  5. In order to adjust the line relief valve, loosen the locknut and turn the adjustment screw until the pressure reading at pressure tap (2) is within the specification. Refer to Table 2.

    Note: Turn the adjustment screw clockwise in order to increase the pressure. Turn the adjustment screw counterclockwise in order to decrease the pressure.

    Note: Always make final pressure adjustment on pressure rise.

  6. Tighten the locknut on the line relief valve.

Bucket / Heel / Tilt Cylinder

Adjustment (Cylinder Head End)



    Illustration 11g02102290
    Line relief valve for the bucket cylinder head end

  1. To adjust the line relief valve pressure setting of the bucket cylinder head end, move the joystick for the bucket until the bucket is at the full BUCKET CLOSE position (full extension of bucket cylinder). Hold the joystick for the bucket in this position.

  2. Check the pressure reading in the bucket cylinder head end at pressure tap (1).

  3. Return the joystick for the bucket to the NEUTRAL position.

  4. The pressure reading should be within the specification. Refer to Table 2. If the pressure reading at pressure tap (1) is not within the specification, adjust the line relief valve for the bucket cylinder head end.

  5. In order to adjust the line relief valve, loosen the locknut on the bucket line relief valve. Turn the adjustment screw until the pressure reading at pressure tap (1) is within the specification. Refer to Table 2.

    Note: Turn the adjustment screw clockwise in order to increase the pressure. Turn the adjustment screw counterclockwise in order to decrease the pressure.

    Note: Always make final pressure adjustment on pressure rise.

  6. Tighten the locknut on the line relief valve.

Adjustment (Cylinder Rod End)



    Illustration 12g02102287
    Line relief valve for the bucket cylinder rod end

  1. To adjust the line relief valve pressure setting of the bucket cylinder rod end, move the joystick for the bucket until the bucket is at the full BUCKET OPEN position (full retraction of bucket cylinder). Hold the joystick for the bucket in this position.

  2. Check the pressure reading in the bucket cylinder rod end at pressure tap (1).

  3. Return the joystick for the bucket to the NEUTRAL position.

  4. The pressure reading should be to the specification. Refer to Table 2. If the pressure reading at pressure tap (1) is not within the specification, adjust the line relief valve.

  5. In order to adjust the line relief valve, loosen the locknut on the bucket line relief valve. Turn the adjustment screw until the pressure reading at pressure tap (1) is within the specification. Refer to Table 2.

    Note: Turn the adjustment screw clockwise in order to increase the pressure. Turn the adjustment screw counterclockwise in order to decrease the pressure.

    Note: Always make final pressure adjustment on pressure rise.

  6. Tighten the locknut on the line relief valve.

Thumb Cylinder

Adjustment (Cylinder Head End)



    Illustration 13g02148871
    Line relief valve for the thumb cylinder head end

  1. To adjust the line relief valve pressure setting of the thumb cylinder head end, press the device of activation for the thumb until the thumb is at the full THUMB CLOSE position (full extension of thumb cylinder). Hold the device of activation for the thumb in this position.

  2. Check the pressure reading in the thumb cylinder head end at pressure tap (1).

  3. Return the device of activation for the thumb to the NEUTRAL position.

  4. The pressure reading should be within the specification. Refer to Table 2. If the pressure reading at pressure tap (1) is not within the specification, adjust the line relief valve for the thumb cylinder head end.

  5. In order to adjust the line relief valve, loosen the locknut on the thumb line relief valve. Turn the adjustment screw until the pressure reading at pressure tap (1) is within the specification. Refer to Table 2.

    Note: Turn the adjustment screw clockwise in order to increase the pressure. Turn the adjustment screw counterclockwise in order to decrease the pressure.

    Note: Always make final pressure adjustment on pressure rise.

  6. Tighten the locknut on the line relief valve.

Adjustment (Cylinder Rod End)



    Illustration 14g02148872
    Line relief valve for the thumb cylinder rod end

  1. To adjust the line relief valve pressure setting of the thumb cylinder rod end, press the device of activation for the thumb until the thumb is at the full THUMB OPEN position (full retraction of thumb cylinder). Hold the device of activation for the thumb in this position.

  2. Check the pressure reading in the thumb cylinder rod end at pressure tap (1).

  3. Return the device of activation for the thumb to the NEUTRAL position.

  4. The pressure reading should be to the specification. Refer to Table 2. If the pressure reading at pressure tap (1) is not within the specification, adjust the line relief valve.

  5. In order to adjust the line relief valve, loosen the locknut on the thumb line relief valve. Turn the adjustment screw until the pressure reading at pressure tap (1) is within the specification. Refer to Table 2.

    Note: Turn the adjustment screw clockwise in order to increase the pressure. Turn the adjustment screw counterclockwise in order to decrease the pressure.

    Note: Always make final pressure adjustment on pressure rise.

  6. Tighten the locknut on the line relief valve.

Worksheet

Table 2
"Relief Valve (Line) - Test and Adjust" 
Date  Machine Serial Number 
  Machine Settings  Main Relief Pressure(1) 
35000 ± 500 kPa (5075 ± 73 psi)
Cylinder  Cylinder Position  Power Shift Pressure  Engine Speed  Relief Pressure Setting  Actual 
Boom  Extended  2500 ± 50 kPa (363 ± 7 psi)  Speed Dial 2
AEC switch OFF 
40000 + 2000 - 500 kPa (5802 + 290 - 73 psi)   
Retracted 3700 ± 50 kPa (537 ± 7 psi)  Speed Dial 2
AEC switch OFF 
37000 + 2000 - 500 kPa (5366 + 290 - 73 psi)   
Stick  Extended  2800 ± 50 kPa (406 ± 7 psi)  Speed Dial 2
AEC switch OFF 
37000 + 2000 - 500 kPa (5366 + 290 - 73 psi)   
Retracted 2500 ± 50 kPa (363 ± 7 psi)  Speed Dial 2
AEC switch OFF 
40000 + 2000 - 500 kPa (5802 + 290 - 73 psi)   
Bucket / Heel / Tilt  Extended  3700 ± 50 kPa (537 ± 7 psi)  Speed Dial 2
AEC switch OFF 
37000 + 2000 - 500 kPa (5365 + 290 - 73 psi)   
Retracted
Thumb  Extended    Speed Dial 10
AEC switch OFF 
36990 ± 1000 kPa (5365 ± 145 psi)   
Retracted
(1) System pressure setting before temporary setting adjustment

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