- Underground Articulated Truck:
- AD30 (S/N: DXR1-UP)
The information in this article has changed. Replace this article with the following information.
Transmission Hydraulic Control Clutch Pressure - Test
| Required Tools | ||
| Part Number | Description | Quantity |
| 8T-0855 | Pressure Gauge (0 to 4,000 kPa (0 to 580 psi)) | 2 |
| 177-7862 | Hose Assembly | 2 |
| 6V-4143 | Coupler | 4 |
| 5P-6586 | Cover (Test) | 1 |
| 8T-5200 | Generator and Counter Signal Group | 1 |
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Personal injury or death can result from sudden machine movement. Sudden movement of the machine or release of oil pressure can cause injury to persons on or near the machine. To help prevent possible injury or death, refer to the information in Testing and Adjusting, "Machine Preparation for Troubleshooting". |
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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 Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Caterpillar products. Dispose of all fluids according to local regulations and mandates. |
| NOTICE |
|---|
Make sure the drive axles are removed or disconnect the drive shaft from the machine for this test or the clutches of the transmission will be damaged. |
Note: Make sure that the filters and the screens are clean before you test any pressures. The transmission oil must be cold when you perform this test.
Procedure
- Park the machine on a hard level surface. Stop the engine, engage the parking brake and block the wheels.
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| Illustration 1 | g01056600 |
(1) Speed clutch pressure port "P1" (2) Direction clutch pressure port "P2" | |
- Remove the cover from the transmission hydraulic control.
- Remove the plug from speed clutch pressure port (1). Remove the plug from direction clutch pressure port (2) .
- Install 5P-6586 Cover (Test).
- Install 8T-0855 Pressure Gauge (0 to 4,000-kPa (0 to 580-psi)) in speed clutch pressure port (1) and direction clutch pressure port (2) .
- Disconnect the electrical harness from the output speed sensor on the rear of the transmission and connect an 8T-5200 Generator and Counter Signal Group. This equipment is used to simulate machine movement and changes in speed. For details on the use of 8T-5200 Generator and Counter Signal Group refer to Special Instruction, SEHS8579.
- Disconnect the electrical harness from the torque converter lock up clutch and solenoid valve.
- Start the engine and run at low idle. Move the transmission shift lever to the DRIVE "D" position.
Note: Ensure that the engine speed is not increased above low idle during the test procedure.
- The pressure gauge attached to speed clutch pressure port (1) should read 2550 ± 70 kPa (370 ± 10 psi). The pressure gauge attached to direction clutch pressure port (2) should read 380 ± 35 kPa (55 ± 5 psi) less than speed clutch pressure port (1) .
- Gradually increase the setting on 8T-5200 Generator and Counter Signal Group to simulate an increase in machine ground speed so that the transmission upshifts through all gears. The pressure readings should be consistent after each upshift.
- Stop the engine and engage the parking brake.
- Remove the test equipment and the 5P-6586 Cover (Test).
- Install the transmission hydraulic control valve group cover. Reconnect the speed sensor harness and the torque converter lockup control valve harness.
Problem: The pressures at the direction clutch port or the speed clutch port are incorrect.
Probable Cause
- The selector and pressure control valve needs adjusting. Refer to Testing and Adjusting, "Selector and Pressure Control Valve - Adjust"
- There are worn or damaged clutch ring seals.