| Required Tools | |||
| Tool | Part Number | Part Description | Qty |
| A | Test Tooling | ||
| 7X-3162 | Swivel Adapter | 1 | |
| 6V-3965 | Fitting As (1) | 1 | |
| 7X-2444 | Tee | 1 | |
| 8C-6866 | Connector | 2 | |
| 1S-8937 | Needle Valve | 1 | |
| B | Gauge | ||
| 1U-5796 | Pressure Differential Tool Gp | 1 | |
| 8T-0861 | Pressure Gauge (1) | 1 | |
| 6V-4144 | Quick Connect Coupler | 1 | |
| ( 1 ) | Part of 1U-5796 Pressure Differential Tool Gp |
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Personal injury can result from hydraulic oil pressure and hot oil. Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system. Make sure all of the work tools have been lowered to the ground, and the oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand. |
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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. |
Machine Preparation
Prepare the machine for testing by completing the procedure that is specified in the Service Manual module Testing and Adjusting, "Machine Preparation for Troubleshooting" for the machine that is being serviced.
Testing and Adjusting Procedure
Using a differential pressure gauge is the preferred method of checking the margin pressure.
- Turn the engine start switch to the OFF position.
- Remove signal line (1) from the pump control valve. Install test tooling (A) between the pump control valve and hose assembly.
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| Illustration 1 | g01097041 |
Location for earlier models (1) Signal line for the hydraulic fan pump. | |
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| Illustration 2 | g01096843 |
Location for later models (1) Signal line for the hydraulic fan pump. | |
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| Illustration 3 | g00714541 |
Test tooling (A) . | |
- Attach the proper tooling that is contained in the pressure differential group (B) to the pressure tap (2) .
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| Illustration 4 | g01096845 |
Location for earlier models (2) Pressure tap. | |
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| Illustration 5 | g01096846 |
Location for later models (2) Pressure tap. | |
- Engage the parking brake.
- Ensure that the transmission direction control is in the NEUTRAL position.
- Start the engine. Warm the hydraulic oil to normal operating temperature of approximately 49 °C (120 °F).
- Increase the engine speed to high idle.
- Slowly turn the handle of the needle valve on test tooling (A) in the counterclockwise direction. The pressure that is shown on test gauge (B) should be 2000 ± 100 kPa (290 ± 15 psi).
- Turn the engine start switch to the OFF position.
- If the pressure is correct proceed to step 17. If the margin pressure is not correct proceed to the following step for instructions to adjust the margin pressure.
- Remove cap (6) from the pump control valve.
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| Illustration 6 | g01097045 |
Pump Control Valve (6) Cap. (7) Locking nut. | |
- Loosen locking nut (7) and turn the adjustment screw in order to change the pressure setting. Turn the adjustment screw clockwise in order to increase the pressure setting. Turn the adjustment screw counterclockwise in order to decrease the pressure setting.
One full turn of the adjustment screw will change the margin pressure approximately 1700 kPa (250 psi).
- Tighten locking nut (7) .
- Install cap (6) .
- Start the engine and measure the new pressure setting.
- If the pressure is not correct, repeat steps 4 through 15, as needed.
- When the pressure setting is within the specification, turn the engine start switch to the OFF position. Remove test gauge (B) and test tooling (A) from the machine. Connect hose assembly (1) to the pump control valve.