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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 product. 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 on Caterpillar products. Dispose of all fluids according to local regulations and mandates. |
| Required Tools | ||
| Part Number | Description | Qty |
| 1U-5481 | Pressure Gauge Group | 1 |
| 1U-5482 | Pressure Adapter Group | 1 |
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, "System Pressure - Release" for the machine that is being tested.
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 compensator 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 pressure compensator of the steering pump fails to regulate the pump pressure to 24100 ± 350 kPa (3500 ± 50 psi).
Use the following procedure to check the pressure setting for the backup relief valve.
- Position the machine so that the machine is in the STRAIGHT AHEAD position.
- Move steering frame lock into the LOCKED position.
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| Illustration 1 | g00834018 |
Steering Frame Lock in the LOCKED Position | |
- Engage the parking brake. Move the transmission direction control switch to the NEUTRAL position.
- Attach the correct hose assembly from the 1U-5482 Pressure Adapter Group to the pressure tap. Attach the opposite end of the hose assembly to a 0 to 40000 kPa (0 to 5800 psi) pressure gauge in the 1U-5481 Pressure Gauge Group. The pressure tap is located on the top of the steering control valve. The steering control valve is located on the left side of the machine under the access panel on the cab platform.
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| Illustration 2 | g00558468 |
Location of the Steering Control Valve | |
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| Illustration 3 | g00836548 |
Pressure tap for steering pump pressure | |
- Backup relief valve (1) is located on the bottom of the steering control valve. Loosen locknut (2) on steering backup relief valve (1). Turn adjustment screw (3) counterclockwise by two full turns. This will lower the pressure of the backup relief valve below the pressure of the pressure compensator valve of the steering pump. Therefore, the backup relief valve will open before the steering pump reaches a stall condition.
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| Illustration 4 | g00836552 |
Location of the Backup Relief Valve on the Steering Control Valve (1) Backup relief valve. | |
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| Illustration 5 | g00836554 |
Backup Relief Valve (2) Locknut. (3) Adjustment screw. | |
- Start the engine. Operate the engine at high idle. Move the implement control lever to the LIFT position in order to increase the oil to normal operating temperature. The oil is at normal operating temperature when the hydraulic oil temperature gauge is between the first mark and the second mark.
- After the oil has reached normal operating temperature, lower the work tool until the work tool is slightly off the ground. Run the engine at high idle.
- Move the STIC steering control lever (if equipped) or turn the steering wheel (if equipped) against the steering frame lock. Continue to move the STIC steering control lever (if equipped) or turn the steering wheel (if equipped) 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 STIC steering control lever (if equipped) or the steering wheel (if equipped) and wait for 30 seconds before you repeat the step.
- Record the pressure reading on the pressure gauge. The reading should be lower than 24100 ± 350 kPa (3500 ± 50 psi). Turn adjustment screw (3) slowly in the clockwise direction while you observe the pressure gauge. The pressure reading should increase to 24100 ± 350 kPa (3500 ± 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 (2) to a torque of 50 ± 7 N·m (37 ± 5 lb ft).
Note: The pressure stops rising because the steering pump has reached a stall condition. This reduces pump output.
- Lower the work tool and any attachment to the ground. Stop the engine.
- Relieve the hydraulic pressure.
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, "System Pressure - Release" for the machine that is being tested.
- Remove the hose assembly and the pressure gauge from the pressure tap.