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Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine. To prevent possible injury, perform the procedure that follows before testing and adjusting the power train. |
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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, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat products. Dispose of all fluids according to local regulations and mandates. |
Introduction
The hydrostatic drive system is adjusted by the cross over relief.
Required Tools
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| Illustration 1 | g01330462 |
(A) Tooling | |
| Required Tools | ||||
| Description | Part Number | Quantity | ||
| A | A1 | 8T-0861 | Pressure Gauge (60000 kPa (8702 psi)) | 1 |
| A2 | 171-1879 | Adapter | 1 | |
| A3 | 187-3547 | Fitting | 1 | |
| A4 | 187-3546 | Coupler | 2 | |
| A5 | 177-7865 | Hose As | 1 | |
| Laptop Computer with Caterpillar Electronic Technician (ET) | 1 | |||
| 275-5120 | Communication Adapter Group | 1 | ||
| 139-4166 | Data Link Cable Assembly | 1 | ||
Note: Use the gauge reading for all adjustments. Do not use the values from the ET screens.
Adjusting Procedure
- If the engine is still running, stop the engine.
- Remove the belly guard on the bottom of the machine.
- Locate the travel pressure sensor at the rear of the machine. The sensor is located on the left side hydrostatic motor. Disconnect the machine harness from the sensor.
Note: When, the harness is disconnected from the sensor an active diagnostic will be present on the ECM. Disregard this code. Upon completion of the adjustment, reconnect the sensor and clear the logged diagnostic code.
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| Illustration 2 | g01341336 |
Location of the travel pressure sensor on the top of the hydrostatic motor | |
- Turn the screw (1) counterclockwise and remove panel (2) .
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| Illustration 3 | g01339696 |
The location of the access port for the Caterpillar electronic communications (ET) | |
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| Illustration 4 | g01332212 |
- Connect the communications adapter to the service tool connector (3) .
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| Illustration 5 | g01332219 |
- Remove the access panel in the floor of the cab.
- Connect the hose assemblies (A) to pressure tap (4) and (5) .
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| Illustration 6 | g01339725 |
Location of front pump (5) and rear pump (4) | |
- Locate the remote port panel on the left side of the machine.
- Connect the hose assemblies (A) to pressure tap (6) and (7) .
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| Illustration 7 | g01332225 |
(S/N: NCF1-62FBH1-1254DHA1-1558) | |
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| Illustration 8 | g02625909 |
(S/N: NCF63-UPFBH1255-UPDHA1559-UP) | |
- Enter the machine.
| NOTICE |
|---|
If the adjustment screw bottoms out when you turn the adjustment screw clockwise, do not exceed a torque of 2 N·m (18 lb in). Damage to the valve could result if you exceed this torque. |
- Fasten the seat belt.
- Start the engine.
- Use ET to set the machine in STALL TEST MODE. Follow the instructions on the Caterpillar Electronic Technician. Refer to Testing and Adjusting, "Transmission Stall Test - Setup".
- Increase the engine speed to 2100 ± 50 rpm. Set the valve when the temperature of the case sump reaches a minimum of 50 °C (122 °F). Stall one side at a time.
- Move the travel control to the FORWARD position and record both loop pressures. Pressure at the crossover relief valve should be 48250 ± 150 kPa (7000 ± 20 psi) at locations (6) and (3) .
- Move the travel control to the REVERSE position and record both loop pressures. Pressure at the crossover relief valve should be 47650 ± 150 kPa (6910 ± 20 psi) at locations (7) and (4) .
| | |
| Illustration 9 | g01332225 |
(S/N: NCF1-62FBH1-1254DHA1-1558) | |
| | |
| Illustration 10 | g02625909 |
(S/N: NCF63-UPFBH1255-UPDHA1559-UP) | |
- Return the travel control to the HOLD position.
- Decrease engine speed to LOW IDLE.
- Stop the engine.
- Remove the cap from crossover relief valve (8) that is not within the specification.
For the front pump the crossover relief valve for REVERSE is on the left side of the pump when you view the pump from the operator's seat. The crossover relief valve for FORWARD is on the right side of the pump when you view the pump from the operator's seat.
For the rear pump the crossover relief valve for REVERSE is on the right side of the pump when you view the pump from the operator's seat. The crossover relief valve for FORWARD is on the left side of the pump when you view the pump from the operator's seat.
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| Illustration 11 | g01331863 |
- Loosen locknut (9) .
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| Illustration 12 | g01332295 |
- Turn adjustment screw (10) in order to adjust the relief pressure. Turn the adjustment screw clockwise in order to increase the pressure or turn the adjustment screw counterclockwise in order to decrease the pressure. One full turn of the adjustment screw is approximately 19000 kPa (2756 psi).
- Maintain the position of adjustment screw (10) as you tighten locknut (9) .
Note: When you adjust the crossover relief valve in order to decrease the pressure, turn the adjustment screw for an additional one quarter turn past the estimated adjustment setting. Then, turn the adjustment screw clockwise for one quarter turn.
- Repeat Step 10 through Step 23 until the relief pressure is correct.
- Reconnect the travel pressure sensor to the electrical harness. Reinstall the belly guard.
Note: There will be an active diagnostic for the pressure sensor until the harness is reconnected. Once, the harness is reconnected clear the logged codes and make sure that active codes are cleared.