| REQUIRED TOOLS | ||
| Part Number | Description | Qty |
| 1U-5755 | Hose | 1 |
| 6V-4143 | Coupler Assemblies | 2 |
| 8T-0860 | Gauge 0 to 40,000 kPa | 1 |
| 6V-3989 | Unvalved Nipple | 1 |
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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 |
|---|
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. |
The following tests are performed in order to determine if a line relief valve is damaged or if a line relief valve is incorrectly set.
Before any tests are performed, prepare the machine for troubleshooting. Refer to Testing and Adjusting, "Machine Preparation". Before any tests are performed, visually inspect the complete hydraulic system. Refer to the Testing and Adjusting, "Visual Inspection".
- Engage the parking brake. Stop the engine.
- Raise the cab of the machine. Refer to the Operation and Maintenance Manual, "Cab Support Operation" for the correct procedure.
- Install a 8T-0860 Gauge to the test port (1) by using the 1U-5755 Hose .
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| Illustration 1 | g00898903 |
(1) Test port for the work tool system (2) Main relief valve for the work tool | |
- Remove the end cap (3) from the main relief valve (2) .
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| Illustration 2 | g00563593 |
(2) Main relief valve for the work tool (3) Cap (4) Locknut | |
- Loosen the locknut (4). Turn the adjustment screw on the main relief valve clockwise for one and one-half turns. This will increase the main relief valve setting by 13500 kPa (1960 psi).
- Tighten the locknut (4) and install the cap (3) .
- Lower the cab. Secure the hydraulic line so that the pressure gauge can be viewed by the operator during the test. Make sure that the hoses are not pinched when the cab is lowered.
- Sit in the operator's seat. Fasten the seat belt and lower the armrest. Start the engine. Disengage the parking brake.
- Tilt back the work tool.
- Run the engine at low idle.
- Press and hold the left side of the control switch for the auxiliary circuit on the pilot operated hydraulic control ( work tool). Record the pressure at the stall condition. Press and hold the right side of the control switch for the auxiliary circuit. Record the pressure at the stall condition.
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| Illustration 3 | g00788698 |
| NOTICE |
|---|
Do not stall the hydraulic system for more than 10 seconds. If necessary, release the work tool from the stall condition and wait 30 seconds before you repeat the following step. |
- Hold the hydraulic control until a stall condition exists in the following positions: RAISE, TILT FORWARD and TILT BACK. Record the pressures that exist at each of the positions.
- The pressures that are recorded should be equal to the pressures that are listed in the following table:
Show/hide table
Table 2 LINE RELIEF VALVE PRESSURES Position Lift Cylinder Head
RAISE position
27600 ± 700 kPa (4000 ± 100 psi)Tilt Cylinder Head
TILT FORWARD position
24500 ± 700 kPa (3555 ± 100 psi)Tilt Cylinder Rod
TILT BACK position
27600 ± 700 kPa (4000 ± 100 psi)Auxiliary Circuit
24500 ± 700 kPa (3555 ± 100 psi)
- Tilt the work tool until the work tool is parallel with the ground. Stop the engine. If the pressure readings are within specifications, proceed to step 21. If the pressure readings are not within specifications, proceed to step 15.
- Release the hydraulic system pressure. Refer to Testing and Adjusting, "Hydraulic System Pressure - Release" for the correct procedure.
- Raise the cab of the machine.
- Remove the cap (10) from the relief valve (9) that needs to be adjusted.
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| Illustration 4 | g00804659 |
(5) Auxiliary line relief valve (6) Line relief valve for the tilt cylinder head (7) Line relief valve for the tilt cylinder rod (8) Line relief valve for the lift cylinder head | |
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| Illustration 5 | g00788911 |
(9) Line relief valve (10) Cap (11) Locknut | |
- Loosen locknut (11). The adjustment screw is under the cap. Turn the adjustment screw clockwise in order to increase the relief valve setting. Turn the adjustment screw counterclockwise in order to decrease the relief valve setting.
- Tighten the locknut (11) and install the cap (8) .
- Repeat steps 7 through 14.
- Raise the cab.
- Reset the main relief valve to the correct setting. Refer to the Testing and Adjusting, "Main Relief Valve - Test and Adjust".
- Remove the test equipment.
- Lower the cab and bolt down the cab. Refer to the Operation and Maintenance Manual, "Cab Support Operation".