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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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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 attachments have been lowered, 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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Escaping fluid under pressure, even a pinhole size leak, can penetrate body tissue, causing 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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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 in Caterpillar machines. Dispose of all fluids according to local regulations and mandates. |
Introduction
The following test procedure will check in order to make sure that the high pressure relief valve for the reverse propel circuit is at the correct pressure setting. The following adjustment procedure contains the necessary information in order to adjust the high pressure relief valve to the correct pressure setting.
Required Tools
Note: You will need two sets of tooling (A) in order to complete the following procedures.
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| Illustration 1 | g01126859 |
| Required Tools | ||||
|---|---|---|---|---|
| Tooling | Item | Part Number | Description | Qty |
| A | A1 | 177-7860 | Hose As | 2 |
| A2 | 6V-4143 | Quick Connect Couplers | 4 | |
| A3 | 6V-3989 | Fittings | 2 | |
| A4 | 8T-0861 | Pressure Gauge ( 60000 kPa (8700 psi)) |
2 | |
Test Procedure (Reverse Relief Valve)
- Use the following procedure before you perform testing and adjusting:
- Place the propel control lever in NEUTRAL.
- Place wedges of wood under each drum.
- Make sure that the parking brake is applied.
- Place the propel control lever in NEUTRAL.
- Disconnect connector (1) for the brake and shift valve.
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| Illustration 2 | g01126792 |
(1) Electrical connector for the solenoids on the brake and shift valve | |
- Connect one set of tooling (A) to pressure tap (4). Connect one set of tooling (A) to pressure tap (5) .
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| Illustration 3 | g01126795 |
Propel Pump (2) Propel pump (3) Cap for the relief valve (reverse) (4) Relief valve pressure tap (reverse) (5) Relief valve pressure tap (forward) (6) Cap for the relief valve (forward) | |
- Loosen the adjuster nut on the pressure override relief valve (POR). Turn adjustment screw (7) clockwise. Turn one full revolution. Turn one revolution. Tighten the locknut.
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| Illustration 4 | g01126796 |
Cross Section Of The Pump Head (3) Cap for the relief valve (reverse) (6) Cap for the relief valve (forward) (7) Adjustment screw (POR) (8) Reverse relief valve cartridge | |
- Release the parking brake.
- Start the engine. Run the engine at high idle.
- Move the propel control lever to the full reverse direction. Read the maximum pressure at pressure tap (4). The relief valve pressure should be 45000 ± 1400 kPa (6525 ± 200 psi).
- If the relief valve pressure is at the correct pressure setting the test is complete.
- Readjust the pressure override valve back to the original position. Turn adjuster (7) counterclockwise. Turn one full revolution.
- Reconnect connector (1) for the brake and shift valve.
- If the relief valve pressure is not at the correct pressure setting, perform the following adjustment procedure for the reverse main relief valve.
Adjustment Procedure (Reverse Relief Valve)
- Stop the engine.
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| Illustration 5 | g01126799 |
Relief Valve Cartridge (8) Reverse relief valve cartridge (9) Locking setscrew (10) Spindle (adjuster) | |
- Remove the cap on reverse relief valve cartridge (8) .
- Remove reverse relief valve cartridge (8). Reinstall the cap on reverse relief valve (8), so the oil does not leak during the adjustment to the cartridge.
- Clamp the cartridge in a soft vise jaw. See the arrows in illustration 5. Loosen locking setscrew (9) with a 3 mm allen wrench.
- Use a 5 mm wrench to turn spindle (10). The adjustment will be for the pressure. Turn the spindle clockwise in order to increase pressure. Turn the spindle counterclockwise in order to decrease pressure. One full turn of spindle (10) equals 4400 kPa (638 psi).
- Tighten locking setscrew (9) .
- Remove the reverse relief valve from the vise.
- Reinstall reverse relief valve cartridge (8). Install the cap on the relief valve. Tighten to the torque specifications.
- Start the engine. Check the pressure at tap (4) .
- Stop the engine.
- Readjust the pressure override valve back to the original position. Turn adjuster (7) counterclockwise. Turn one full revolution.
- Reconnect connector (1) for the brake and shift valve.
Test and Adjustment Procedures (Forward Relief Valve)
Follow the same test and adjustment procedures as the reverse relief valve test. Place the propel control lever in the FORWARD position. The forward relief valve cartridge is under cap (6). The pressure is checked at pressure tap (5) .
If the minimum low pressure is not obtainable, there is too much leakage in the internal circuit.