980G Wheel Loader Steering System Caterpillar

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Personal injury or death can result if two persons are not used in the following procedure.

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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.

Before proceeding to the test procedure that follows, complete the procedure:

• Machine Preparation for Troubleshooting

Reference: For more information on preparing the machine for troubleshooting, refer to the Service Manual module for Testing and Adjusting, SENR5879, "980G Wheel Loader Steering System", "Machine Preparation for Troubleshooting".

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Illustration 1	g00274661
Steering Frame Lock

1. Install the steering frame lock in order to keep the machine from turning.

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

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Illustration 2	g00275523
Torque Converter Housing (right side of machine) (1) Steering pump. (2) Discharge port. (3) Compensator. (4) Compensator valve.

3. Install a 0 to 40000 kPa (0 to 5800 psi) pressure gauge port (2) .

4. Start the engine. Operate the engine at high idle. Move the tilt control lever to the TILT BACK position in order to increase the oil to normal operating temperature. The oil is at normal operating temperature when the hydraulic oil temperature indicator is between the first mark and the second mark.

5. After the oil has reached normal operating temperature, lower the bucket to the ground. Stop the engine.

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Illustration 3	g00484273
Steering Control Valve (5) Steering cylinder crossover relief valve.

Note: The steering control valve is located on the back side of the hydraulic tank.

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Illustration 4	g00484274
Steering Cylinder Crossover Relief Valve (6) Locknut. (7) Adjustment screw.

Note: Relief valve (5) is located on the steering control valve. The backup relief valve is facing the back of the machine.

6. Loosen locknut (6) on steering crossover relief valve (5). Turn adjustment screw (7) counterclockwise by two full turns. This will lower the setting of the steering crossover relief valve to a setting that is lower than the cutoff pressure of the steering pump.

7. Start the engine. Raise the bucket and any attachments slightly off the ground. Run the engine at high idle.

Note: During the following step, do not keep the steering pump at stall condition for more than ten seconds. If necessary, release the steering wheel and wait for 30 seconds before you repeat the step.

8. Turn the steering wheel against the steering frame lock. Hold the steering wheel in the FULLY TURNED position in order to obtain a reliable pressure reading.

9. Record the pressure reading on the pressure gauge. The reading should be lower than 24000 ± 500 kPa (3480 ± 70 psi). Turn adjustment screw (7) slowly in the clockwise direction while you observe the pressure gauge. The pressure reading should increase to 24000 ± 500 kPa (3480 ± 70 psi). Then, the pressure should stop rising. Stop turning adjusting screw (7) when the pressure stops rising.

Note: The pressure stops rising because the steering pump has reached a stall condition.

10. When the pump stall pressure is reached, continue to turn adjustment screw (7) clockwise by an additional 3/4 turn. Tighten locknut (6) to a torque of 13 ± 2 N·m (10 ± 1 lb ft).

11. Lower the bucket and any attachments to the ground. Stop the engine.