| Required Tools | |||
| Tool | Part Number | Part Description | Qty |
| A | Test Gauge Hose | ||
| 6V-4143 | Quick Connect Coupler (1) | 1 | |
| 177-7860 | Hose As (1) | 1 | |
| 8T-4188 | Union Adapter (1) | 1 | |
| 6V-3966 | Fitting As (1) | 1 | |
| B | Test Gauge | ||
| 8T-0859 | Pressure Gauge (1) | 1 | |
| 6V-4144 | Quick Connect Coupler (1) | 1 | |
| ( 1 ) | Part of 4C-4892 Hydraulic Test Fitting Gp |
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Personal injury or death can result if two persons are not used in the following procedure. |
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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 |
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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 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. |
Machine 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.
Testing and Adjusting Procedure
- Stop the engine. Place the transmission direction selector in the NEUTRAL position.
- Engage the parking brake.
- Depress the brake pedal repeatedly in order to release all oil pressure from the brake circuit.
- Remove the protective cap from test port (1) in order to test the oil pressure of the rear service brakes. Install the 8T-0859 Pressure Gauge .
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| Illustration 1 | g00476720 |
Location of the Service Brake Control Valve (1) Test port for the rear service brakes. (2) Test port for the front service brakes. | |
Note: The service brake control valve is located under the operator's cab just behind the steering shaft.
- Observe the pressure gauge. Before you start the engine, the oil pressure must be at the pressure of the hydraulic oil tank.
- Start the engine and allow the hydraulic oil to reach normal operating temperature and normal operating pressure.
- Hold down the brake pedal and look at the pressure gauge. The brake pressure should be at 4310 ± 350 kPa (625 ± 50 psi).
- If the brake pressure is not in the correct range but the brake accumulator charging valve is functioning correctly, replace the brake control valve.
- Repeat this procedure at test port (2) in order to test the oil pressure of the front service brakes.
Note: The pressure from the upper brake port should be approximately 350 kPa (50 psi) higher than the pressure from the lower brake port.