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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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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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| NOTICE |
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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 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. |
Introduction
The transmission hydraulic control relief valve regulates the pressure of the oil that is used to control the transmission system. Also, this relief valve regulates the pressure of the oil that is used for the torque converter.
Required Tools
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| Illustration 1 | g01089423 |
| Required Tools | ||||
|---|---|---|---|---|
| Tooling | Item | Part Number |
Description | Qty |
| A | A1 | 8T-0855 | Pressure Gauge | 1 |
| A2 | 6V-3989 | Fitting | 1 | |
| A3 | 6V-4143 | Quick Connect Coupler | 2 | |
| A4 | 177-7861 | Hose As | 1 | |
Testing Procedure
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| Illustration 2 | g01289791 |
The relief pressure for the transmission hydraulic control system can be measured at pressure tap (1) on the transmission hydraulic control relief valve.
- Install Tooling (A) on pressure tap (1) .
- Start the engine. Warm the oil until the oil reaches 47 °C (116 °F).
- Operate the engine at low idle. Observe the pressure gauge. The relief pressure for the transmission hydraulic control must be within the values that are shown in Systems Operation, Testing and Adjusting, "Power Train Pressures".
- Operate the engine at high idle. Observe the pressure gauge. The relief pressure for the transmission hydraulic control must be within the values that are shown in Systems Operation, Testing and Adjusting, "Power Train Pressures".
- If the pressure is at the specified level, go to 6. If the pressure is not at the specified level, go to "Adjusting Procedure".
- Shut off the engine. Remove tooling (A) from pressure tap (1) .
Adjusting Procedure
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| Illustration 3 | g01259402 |
The transmission hydraulic control relief valve can be adjusted by increasing or by decreasing the preload on spring (2) .
- Remove cap (3) from the end of the transmission hydraulic control relief valve.
- Turn adjustment screw (4) in the appropriate direction.
Turning the adjustment screw clockwise increases the pressure. Turning the adjustment screw counterclockwise decreases the pressure.
- Recheck the pressure at pressure tap (1). Tighten locknut (5) and replace cover (3) .