Operational Test
- Block the wheels.
- Apply the parking brake.
- Drain all of the reservoirs. Refer to
Draining Reservoirs
in Air Brakes.
- Disconnect the air lines from the differential lock pressure protection
valve supply and the delivery ports.
- Install the test gages and the drain valves on the supply and
the delivery ports.
- Start the engine. Charge the system to the air compressor governor
cutout point.
- Stop the engine.
- Slowly exhaust pressure from the delivery side. Observe the test
gages.
| 8.1. | Ensure that both gauges show a pressure loss until the closing
pressure of the differential lock pressure protection valve is reached. |
| 8.2. | Ensure that the differential lock pressure protection valve closes
within 34 kPa (5 psi) of the rated pressure. |
| 8.3. | If the differential lock pressure protection valve does not close
within the acceptable pressure range, replace the differential lock pressure
protection valve. |
- Drain all of the air reservoirs.
- Remove the drain valves and the test gages.
- Install the air lines.
- Start the engine. Charge the system to the air compressor governor
cutout point.
- Stop the engine.
- Inspect for air leakage.
- Verify proper differential lock operation.
- Remove the wheel blocks.
Air Leakage Test
- Block the wheels.
- Start the engine. Charge the system to the air compressor governor
cutout point.
- Stop the engine.
- Inspect the differential lock pressure protection valve for air
leakage. Air leakage less than a 25.4 mm (1.0 in) bubble in
3 seconds or longer is acceptable.
- If the air leakage is too much, replace the differential lock
pressure protection valve.
- Drain the air pressure from the delivery port. Remove the air
line connected to the delivery port.
- Inspect the delivery port for air leakage. Air leakage less than
a 25.4 mm (1.0 in) bubble in 5 seconds or more is acceptable.
- If the air leakage is too much, replace the differential lock
pressure protection valve.
- Install the air line to the delivery port.
- Remove the wheel blocks.
