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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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| 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. |
Specification
| 980H Brake Accumulator Charging Valve Pressure | ||
| Date | Equipment ID Code | |
| Pump Pressure | Setting | Actual |
| Cut-In Pressure | 11725 ± 345 kPa (1700 ± 50 psi) |
|
| Cut-Out Pressure | 14485 ± 345 kPa (2100 ± 50 psi) |
|
Introduction
This information includes the following test:
- Parking Brake System Pressure - Test
This procedure will check the parking brake control valve for the correct pressure in order to engage the parking brake automatically.
Required Tools
| Required Tools | |||
| Tool | Part Number | Part Description | Qty |
| A | Test Gauge Hose | ||
| 6V-4143 | Coupler (1) | 2 | |
| 6V-3079 | Hose Assembly (1) | 1 | |
| 6V-3966 | Fitting (1) | 1 | |
| B | Test Gauge | ||
| 8T-0852 | Pressure Gauge (2) | 1 | |
| ( 1 ) | Part of 1U-5482 Pressure Adapter Group |
| ( 2 ) | Part of 1U-5481 Pressure Gauge Group |
Test 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.
Test Procedure
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| Illustration 1 | g03420790 |
Location of the Brake Components The operator platform has been removed for clarity in this view. (1) Pressure tap for the service brake system. (2) Parking brake control valve. | |
- Attach the correct hose to pressure tap (1). Use the correct pressure gauge.
- Start the engine and allow the accumulator oil pressure to increase to the cut-in pressure of 11725 ± 345 kPa (1700 ± 50 psi).
Note: Keep the engine running. Allow the accumulator oil pressure to reach cut-out pressure of 14485 ± 345 kPa (2100 ± 50 psi).
- The parking brake control knob needs to be in the disengaged position. The parking brake control knob should be pushed in all the way. Verify that the parking brake is disengaged. Stop the engine.
- Push the brake pedal rapidly several times until the parking brake control knob automatically moves to the engaged position. The parking brake control knob will move outward all the way.
- Read the oil pressure on the gauge.
- If the hydraulic pressure decreases to less than 700 kPa (100 psi), the parking brake control knob should move outward full stroke. If the control knob did not move out fully, the operation of the parking brake control valve is not correct. Perform the next two Steps in order to check control components.
- Start the engine and allow the accumulator oil pressure to reach cut-out pressure. Engage and disengage the parking brake in order to check for proper cable and valve movement. The movement should be smooth and free.
- Check the parking brake cable for the proper adjustment. If the cable is properly adjusted, replace the parking brake control valve.
- A new valve should be tested for proper operation. Recheck using Steps 2 to 6.
- Remove the test equipment.