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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. |
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| NOTICE |
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Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide", for tools and supplies suitable to collect and contain fluids in Caterpillar machines. Dispose of all fluids according to local regulations and mandates. |
Note: Use the information in the reference to prepare the machine for this test. Also, use the information in the reference to relieve any hydraulic pressure that may be in the steering system.
Reference: For the correct procedure to relieve any hydraulic oil pressure that may be in the steering system, refer to the Service Manual module for Testing and Adjusting, SENR1384, "950G Wheel Loader and 962G Wheel Loader Steering System", "Machine Preparation for Troubleshooting".
| Required Tools | |
| Part Number | Description |
| 8T-0860 | Pressure Gauge |
The backup relief valve for the steering system is located on the steering control valve. The backup relief valve controls the pressure in the steering system in case the pressure control section of the steering pump fails.
The backup relief valve for the steering system is set to a higher pressure than the maximum system pressure (pump stall pressure). Therefore, the backup relief valve only operates if the control section of the steering pump fails to regulate the pump pressure to 20000 ± 350 kPa (2900 ± 50 psi).
Use the following procedure to check the pressure setting for the backup relief valve.
- Move steering frame lock (1) to the LOCKED position.
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| Illustration 1 | g00294202 |
Steering Frame Lock in the LOCKED Position (1) Steering frame lock. | |
- Engage the parking brake. Move the transmission direction selector to the NEUTRAL position.
- Attach a 0 to 40000 kPa (0 to 5800 psi) pressure gauge to a section of hydraulic line.
- Install the open end of the hydraulic line to pressure tap (2). Pressure tap (2) is located on the right side of the machine and above the hydraulic oil tank.
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| Illustration 2 | g00317643 |
Pressure Tap for the Steering Pump (2) Pressure tap. | |
- 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 hydraulic oil temperature indicator is between the first mark and the second mark.
- After the oil has reached normal operating temperature, lower the bucket to the ground. Stop the engine.
- Backup relief valve (5) is located on the left end of the steering control valve as you face the right side of the machine. Loosen locknut (4) on steering backup relief valve (5). Turn adjustment screw (3) counterclockwise by two full turns.
Note: In the following illustration, the operator's cab has been removed for clarity.
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| Illustration 3 | g00320447 |
Location of the Backup Relief Valve on the Steering Control Valve (3) Adjustment screw for the backup relief valve. (4) Locknut. (5) Backup relief valve for the steering system. | |
- Start the engine. Position the bucket until the bucket is slightly off the ground. Run the engine at high idle.
- Turn the steering wheel against steering frame lock (1). Continue to turn the steering wheel against the steering frame lock in order to obtain a reliable pressure reading.
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.
- Record the pressure reading on the pressure gauge. The reading should be lower than 20000 ± 350 kPa (2900 ± 50 psi). Turn adjustment screw (3) slowly in the clockwise direction while you observe the pressure gauge. The pressure reading should increase to 20000 ± 350 kPa (2900 ± 50 psi). Then, the pressure should stop rising.
- When the pump stall pressure is reached, continue to turn adjustment screw (3) clockwise by one full turn. Tighten locknut (4) to a torque of 13 ± 2 N·m (115 ± 18 lb in).
Note: The pressure stops rising because the steering pump has reached a stall condition. This reduces pump output.
- Lower the bucket and any attachment to the ground. Stop the engine.
- See the reference at the start of this procedure for the correct method to release any hydraulic pressure that may be in the steering system. Remove the pressure gauge and the hydraulic line from pressure tap (2) .