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Hydraulic oil pressure can remain in the hydraulic system on this machine after the engine and pump have been stopped. Serious injury can result if this pressure is not released before any service is done on the hydraulic system. In order to prevent possible injury, release the hydraulic system pressure before working on any fitting, hose, or hydraulic component. Lower all work tools to the ground before service is started. If the hydraulic system must be serviced, tested, or adjusted with the work tool in the raised position, the work tool and lift cylinders must be supported properly. Always move the machine to a location away from the travel of other machines. Be sure that other personnel are not near the machine when the engine is running and tests or adjustments are being made. |
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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. Dispose of all fluids according to local regulations and mandates. |
Note: Before you perform this adjustment, refer to Testing and Adjusting, "Machine Preparation for Troubleshooting".
The implement relief valve protects the pump for the implement and steering from excessively high pressures.
| Tool | Part Number | Description | Qty |
| D | 1U-9358 | Test Block Manifold | 1 |
| F | 4C-4441 | Relief Valve Test Tool Gp | 1 |
- Move the machine to a smooth horizontal location.
- Chock the wheels.
- Lower all of the implements.
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| Illustration 1 | g01379932 |
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Combination valve (1) Implement relief valve | |
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| Illustration 2 | g01379933 |
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Implement relief valve (2) Retainer assembly (3) Nut | |
Use Tooling (D) in order to test implement relief valve (1) on Tooling (F). The pressure setting for the relief valve is
- Remove implement relief valve (1) from the combination valve and install implement relief valve (1) on Tooling (F).
Reference: Refer to Disassembly and Assembly, "Combination Valve - Disassemble" for the correct procedure to remove the relief valve.
- Purge the air from the system. The temperature of the oil must be
49° ± 3°C (120° ± 5°F) .
- Apply flow of
38 ± 4 L/min (10 ± 1 US gpm) to the valve and note the pressure that opens the relief valve. The pressure setting for the relief valve is27600 ± 400 kPa (3900 ± 60 psi) .
- If the pressure setting is not within the specified pressure range, turn retainer assembly (2) clockwise or turn retainer assembly () counter clockwise. Turn retainer assembly (2) clockwise in order to increase the pressure. Turn retainer assembly (2) counterclockwise in order to decrease the pressure. One turn of the retainer assembly will change the setting approximately
6300 kPa (915 psi) . - Purge the air from the system and repeat Step 1 until you achieve a setting of
27600 ± 400 kPa (3900 ± 60 psi) . - After you set the retainer assembly to the correct pressure setting, tighten nut (3) to
50 ± 7 N·m (37 ± 5 lb ft) . Hold retainer assembly (2) when you tighten nut (3). - Set the test pressure at
5600 ± 70 kPa (812 ± 10 psi) . Maintain the temperature of the oil at26 °C to 28 °C (79 °F to 82 °F) . - Measure the leakage oil. If the leakage oil is greater than
0.004 L/min (0.0011 US gpm) , replace the relief valve. - Remove Tooling (D) and Tooling (F).
- Install the relief valve on the combination valve.
Reference: Refer to Disassembly and Assembly, "Combination Valve - Assemble" for the correct procedure to install the relief valve.