AD30 Underground Articulated Truck Braking System Parking Brake System Pressure - Test Caterpillar

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Personal injury or death can result from sudden machine movement. Sudden movement of the machine or the release of oil under pressure can cause injury to persons on or near the machine. To prevent possible injury before testing and adjusting the hydraulic system, perform the procedure in the Testing and Adjusting, "General Information" section.

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Personal injury or death can result from machine movement. Place blocks in front of and behind the wheels to make sure the machine does not move while the parking brakes are disengaged.

This test will show if the parking brake solenoid valves are operating correctly. This test will also show if the pilot oil pressure reducing valve is set to the correct pressure.

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Parking brake control valve (1) Parking brake pressure tap

1. Remove the protective cover from pressure tap (1). Connect a hose assembly with an 8T-0856 Pressure Gauge 0 to 6000 kPa (0 to 870 psi) to pressure tap (1) on the parking brake control valve.

2. Place blocks in front of the wheels and behind the wheels.

3. Start the engine. Operate the engine at the low idle rpm with the transmission in NEUTRAL.

4. Disengage the parking brake by moving the parking brake switch to the OFF position.

5. Observe the pressure gauge. The pressure reading on the gauge must be at the pilot oil pressure reducing valve setting. The pilot oil pressure reducing valve setting is 3620 ± 70 kPa (525 ± 10 psi).

6. If the pressure reading on the gauge remains at 0 kPa (0 psi) when the parking brake is disengaged, check the operation of the parking brake solenoid valves and the electrical circuit for the parking brake. Refer to the Electrical System Schematic for information on the parking brake electrical circuit.

7. If the pressure reading on the gauge is not within the specification, check the pressure setting of the pilot oil pressure reducing valve. Refer to Braking System, System Operation, Testing and Adjusting, "Pressure Reducing Valve (Pilot Hydraulic) - Test and Adjust" for the machine that is being serviced.

8. When this test is complete, engage the parking brake and stop the engine. Remove the test equipment. Place the protective cover on the pressure tap.