525D, 535D, 545D and 555D Wheel Skidders 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 escaping fluid under pressure. Escaping fluid under pressure, even a very small pin-hole size leak, can penetrate body tissue and cause serious injury and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury. Always use a board or cardboard when checking for a leak.

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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.

Problem 1

The pump makes unusual noise and the cylinder rods do not move evenly. There are also air bubbles in the oil.

Probable causes

1. The viscosity of the oil is incorrect.

2. The pressure and flow compensator valve opens at low oil pressure.

3. There is a loose connection of the oil line on the inlet side of the pump.

4. The pump has too much wear.

5. There is a leak in the oil line between the tank and the pump.

6. Pump cavitation.

7. The pressure and flow compensator valve opens and the pressure and flow compensator valve closes continuously.

Problem 2

The signal pressure is not zero when all the valves are in the HOLD position, and the steering is not active.

Probable causes

1. All controls are not in the HOLD position.

2. The signal network is not vented.

3. There is a leak into the signal resolver network.

4. The brake accumulator charging valve is not adjusted correctly.

5. The relief valve for the priority flow control valve is not adjusted correctly.

Problem 3

The cycle times for the steering and decking blade are too slow.

Probable causes

1. The spool for the main control valve is not fully shifted for the affected circuit.

2. The load signal to the pressure and flow compensator valve is blocked or the signal is partially blocked. There is a leak in the signal network.

3. The setting for the line relief valve for the affected circuit is too low.

4. The line relief valve for the affected circuit is leaking.

5. The piston seals and/or the affected cylinders are worn.

6. The flow control spring is broken.

7. The pump is not at full stroke. The actuator piston is stuck or the swashplate is blocked.

8. The margin pressure setting is too low.

9. The control linkage is not adjusted correctly.

Problem 4

The cycle times for the steering and decking blade are too fast.

Probable causes

1. The margin pressure is set too high.

2. The engine high idle is set too high.

Problem 5

The steering wheel is difficult to turn.

Probable causes

1. The control valve spool is sticky.

2. The steering control linkage needs adjustment or the steering control linkage is binding.

Problem 6

The machine does not turn smoothly.

Probable causes

1. The differential lock is engaged.

2. The bearings in the articulation joint need lubrication or adjustment.

3. The oil level is low.

Problem 7

The machine turns too slowly in both directions.

Probable causes

1. Both of the relief valves are set too low.

2. Not enough flow from the pump.

3. The differential lock is engaged.

4. The pump pressure is too low.

5. The steering control linkage needs adjustment or the steering control linkage is binding.

Problem 8

The machine turns too slowly in one direction.

Probable causes

1. The steering control linkage needs adjustment or the steering control linkage is binding.

2. The control valve spool is not centered.

3. One relief valve is set too low.

Problem 9

The machine does not turn when the steering wheel is turned.

Probable causes

1. The steering control linkage needs adjustment.

2. The steering control linkage is binding or the steering control linkage is broken.

Problem 10

The machine turns when the operator does not turn the steering wheel.

Probable causes

1. The steering control linkage needs adjustment.

2. The control valve spool is not centered.

Problem 11

The secondary steering does not engage while the machine is running.

Probable causes

The wire to the relay coil is broken.

The coil in the relay is shorted to ground.

The electric motor has failed.

The pump is bad.

The primary steering switch has failed in the CLOSED position.

The test switch for the secondary steering has failed in the OPEN position.

Problem 12

The secondary steering is engaged while the machine is running.

Probable causes

The primary steering switch has failed in the OPEN position.

The test switch for the secondary steering has failed in the CLOSED position.

The coil wire to the secondary steering relay that is connected to the Machine ECM is shorted to a ground source.

The secondary steering relay has failed in the CLOSED position.