| 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. |
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".
The following test is performed in order to determine if the main relief valve for the work tool is damaged or improperly set.
- Engage the parking brake. Stop the engine.
- Raise the cab. Refer to Operation and Maintenance Manual, "Cab Support Operation" for the proper procedure.
- Install the 8T-0860 Gauge to test port (1) with a 1U-5755 Hose .
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| Illustration 1 | g00905146 |
- 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. Lower the armrest. Start the engine. Disengage the parking brake.
- Run the engine at low idle.
- Position the work tool in the full tilt back position. Move the pilot operated hydraulic control ( work tool) to the full LOWER position. Hold the pilot operated hydraulic control at that position until a stall condition exists. Record the pressure at the stall condition. Refer to the table below.
Show/hide table
Table 2 MAIN RELIEF PRESSURE Machine Relief Pressure 267/ 277
23000 ± 700 kPa (3335 ± 100 psi)
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| Illustration 2 | g00788651 |
Pilot operated hydraulic control ( work tool) | |
| 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. |
- Release the hydraulic control from the stall condition. Reduce the engine speed to low idle. Tilt the work tool until the work tool is parallel with the ground. Stop the engine.
- If the pressure reading is within specifications, proceed to step 17. If the pressure reading is not to specifications, the main relief valve needs to be adjusted. Proceed to step 11.
- Release the hydraulic system pressure. Refer to Testing and Adjusting, "Hydraulic System Pressure - Release" for the proper procedure.
- Raise the cab of the machine.
- Remove end cap (3) from main relief valve (2) .
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| Illustration 3 | g00905146 |
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| Illustration 4 | g00563593 |
(2) Main relief valve for the work tool (3) Cap (4) Locknut | |
- Loosen locknut (4). The adjustment screw is under the end cap (3). 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 locknut (4) and install cap (3) .
- Lower the cab and repeat steps 6 through 10.
- Raise the cab and remove the test equipment.
- Lower the cab and bolt down the cab. Refer to the Operation and Maintenance Manual, "Cab Support Operation".