525B Wheel Skidder and 535B Wheel Skidder Power Train Caterpillar

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Personal injury can result from hydraulic oil pressure and hot oil. Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system. Make sure all of the attachments have been lowered, oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand.

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Personal injury or death can result from sudden machine movement. Sudden movement of the machine can cause injury to persons on or near the machine. To prevent injury or death, make sure that the area around the machine is clear of personnel and obstructions before operating the machine.

The following procedure is designed to check the pressure for the front differential lock and the rear differential lock.

Before you start the test procedure, perform the following procedure.

• Machine Preparation for Troubleshooting

Reference: For more information on preparing the machine for troubleshooting, refer to the Service Manual module for the power train Testing and Adjusting, "Machine Preparation for Troubleshooting" for the machine that is being serviced.

1. Lower the grapple and the decking blade to the ground.

2. Move the transmission direction switch to the NEUTRAL position. Engage the parking brake.

3. Stop the engine.

4. Install the steering frame lock.

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Illustration 1	g00703624

5. Remove the cover from the right side of the machine.

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Illustration 2	g00704061
Location of the Pressure Tap for the Differential Lock (1) Pressure tap.

6. Connect a 4000 kPa (600 psi) pressure gauge to pressure tap (1) .

7. Start the engine. Run the engine at high idle.

8. Observe the pressure gauge. There should be no pressure.

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Illustration 3	g01185499
(2) Differential lock switch.

9. Press differential lock switch (2) to the ON position.

10. Observe the pressure gauge. The pressure should read 2600 ± 140 kPa (375 ± 20 psi).

11. Observe the pressure when you stall the decking blade. The pressure should read 2600 ± 140 kPa (375 ± 20 psi).

12. If the pressure is correct go to Step 18. If the pressure is incorrect go to Step 13.

13. If the pilot pressure is not within specifications during the stall, then add the proper shims to the pressure reducing valve in order to bring the pressure within the correct specifications.

    Note: Stop the engine and release the hydraulic pressure before performing any repairs or adjustments to the pressure reducing valve.

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Illustration 4	g00717413
Front Right Side of the Machine

14. The pressure reducing valve is located on the front right side of the machine. In order to gain access to the valve, remove the panel from the right side of the machine. See Illustration 4.

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Illustration 5	g00712491
Pressure Reducing Valve (Steering and Decking Blade Valve)

15. The pressure reducing valve is mounted on the end of the steering and decking blade valve. The arrow in Illustration 5 shows the location of a hex plug. The shims are added to the spring chamber which is behind the hex plug. See Illustration 6.

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Illustration 6	g01185507
Pressure reducing valve (3) Hex plug. (4) Shim.

16. Parts Requirement
    • The 3J-7473 Shim thickness is 0.12 mm (0.005 inch).

    • The 3J-7470 Shim thickness is 1.22 mm (0.048 inch).

17. Repeat steps 7 through 12.

18. Stop the engine. Disconnect the pressure gauge.

19. Move the steering frame lock to the STORED position.