538 Forest Machine Machine Systems Relief Valve (Swing) - Test and Adjust Caterpillar

Specifications

Introduction

Two relief valves are located in the head of the swing motor. These relief valves limit the pressure in the left and right swing circuits to the swing relief valve settings. The following procedure will determine if the swing relief valves are out of adjustment.

Required Tools

Illustration 1	g01623868
Tooling group "B" 198-4240 Digital Pressure Indicator Gp

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".
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   Illustration 2	g03861334
   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 a 41,368 kPa (6,000 psi) pressure sensor to pressure tap (2).
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   Illustration 3	g03688946
   Pilot manifold (4) Solenoid valve for swing parking brake (5) Connector

4. Disconnect connector (5) from the solenoid valve for swing parking brake (4).

Test Procedure

1. Start the engine.

2. Place the hydraulic activation control lever in the UNLOCKED position.

3. Increase the hydraulic oil temperature to 55° ± 5°C (131° ± 9°F).

4. Place the machine controls at the following settings: engine speed dial "10" and AEC switch OFF. Refer to Testing and Adjusting, "Engine Performance - Test (Engine Speed)" for engine rpm settings.

5. Move the swing joystick slowly and ensure that the swing parking brake is operating properly.
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   Illustration 4	g03862282
   Swing motor (6) Adjustment plug (7) Locknut (8) Relief valve (right swing) (9) Adjustment plug (10) Locknut (11) Relief valve (left swing)

6. Slowly move the swing joystick for a full SWING RIGHT operation and check the pressure for relief valve (8) at pressure tap (2). Refer to Table 1 for swing relief pressure.

7. Return the joystick to the NEUTRAL position.

8. Slowly move the swing joystick for a full SWING LEFT operation and check the pressure for relief valve (11) at pressure tap (2). Refer to Table 1 for swing relief pressure.

9. Return the joystick to the NEUTRAL position.

Adjustment Procedure

1. To adjust the swing relief valve, loosen the locknut and turn the adjustment plug until the pressure reading at pressure tap (2) is within the specification.

   Note: Turning the adjustment plug clockwise increases the pressure. Turning the adjustment plug counterclockwise decreases the pressure.

   Note: Always make final pressure adjustments on pressure rise.

2. Tighten the locknut to a torque of 117 ± 10 N·m (85 ± 7 lb ft).