950G Wheel Loader, 962G Wheel Loader and IT62G Integrated Toolcarrier Steering System Caterpillar

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Personal injury or death can result from machine articulation or movement. Machine frames can move and a person can be crushed. Connect the steering frame lock link between the front and rear frames before working on machine.

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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.

Performance tests for the steering system can be used for a diagnosis of poor performance and for finding the source of oil leaks inside the hydraulic system.

This section provides probable causes to a known problem. Since there may be several probable causes, specific inspections or specific instrument tests may be recommended. These inspections and tests will help to identify the cause that is most probable.

Note: Make sure that you use hydraulic oil with the correct viscosity for the ambient temperature and for the operating conditions. To determine the correct oil viscosity, see the reference that follows.

Reference: For additional information about the various lubricant viscosities for your machine, refer to the section "Lubricant Viscosities" in the appropriate Operation and Maintenance Manual for your machine.

Problem 1: Turning the steering wheel is difficult.

Probable causes:

1. The oil is cold.

2. There is a restriction in an oil line of the steering metering pump.

3. The backup relief valve for the steering system has malfunctioned.

4. Steering pump pressure is low.

5. Bolts are too tight for the metering section of the steering metering pump.

6. There is a leak or blockage in the load sensing line.

Problem 2: The machine does not turn evenly.

Probable causes:

1. The steering metering pump is sticking.

2. The margin pressure of the steering pump is set too high.

3. The steering control valve spool is sticking.

Problem 3: The machine turns slowly in both directions.

Probable causes:

1. Springs for the steering metering pump are not adjusted correctly.

2. There is not enough flow from the steering pump.

3. The main control spool does not move all the way.

4. The margin pressure setting for the steering pump is too low.

Problem 4: The machine turns too slowly in one direction.

Probable cause:

1. Flow balance adjustment of main control spool is not correct.

Problem 5: The steering wheel turns with slight resistance but the machine does not turn.

Probable causes:

1. Oil is leaking from the steering crossover relief valve.

2. A seal in the piston has worn out.

Problem 6: The machine does not turn when the steering wheel is turned.

Probable causes:

1. The steering metering pump is defective.

2. The steering control valve spool is sticking.

Problem 7: The machine turns slowly in both directions only when the machine turns against a load (high resistance).

Probable causes:

1. Oil is leaking from the relief valve seat or from the seals.

2. The backup relief valve setting of the steering control valve is set too low.

3. The steering pump's high pressure cutoff setting is too low.

Problem 8: The machine does not turn when the steering wheel is turned.

Probable causes:

1. The steering control valve spool is sticking.

2. There is a mechanical failure in the steering linkage.

Problem 9: The machine turns but the operator does not turn the steering wheel.

Probable causes:

1. The spool in the steering control valve does not return to the neutral position correctly.

2. The bolts for the end covers of the steering control valve are too tight.

3. The manufacturing tolerances of the spool in the steering control valve do not permit the spool to return to the neutral position.

   Note: This cause may be corrected on some machines by removing the spool. Then, install the opposite end of the spool first. The spring, the retainer, and the shims must be installed on the opposite end of the spool. An adjustment to the timing of the steering may be necessary.

4. The orifices in the steering control valve are plugged.

5. Springs for the steering metering pump are broken or damaged.

Problem 10: The machine turns too quickly in order to make small steering corrections when the machine moves at fast speeds.

Probable causes:

1. The adjustment of the steering metering pump is not correct.

2. The main control valve spool does not move freely.

3. The orifices in the steering control valve are plugged.

4. The margin pressure of the steering pump is set too high.

Problem 11: The pump makes noise and the steering cylinder rod does not move freely.

Probable causes:

1. There is air in the steering hydraulic circuit.

2. The steering pump has too much wear.

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

4. The viscosity of the oil is incorrect.

5. The backup relief valve for the steering system opens at a low pressure.

6. The oil level in the hydraulic oil tank is low.