Rear Quick Release Double Check Valve Operational Check Operational Check

1. Block the wheels.
2. Start the engine.
3. Charge the system air pressure to the governor cut-out point.
4. Stop the engine.
5. Release the brake pedal and push in the park control knob.
6. Verify that the spring brake chambers release promptly.
7. Pull out on the park control knob. Release the brake pedal.
8. Verify that a prompt exhaust of air occurs at the quick release valve (double check type) exhaust port.
9. Test the slack adjuster in order to verify that the spring brake is applied.
10. Remove the wheel blocks.

Rear Quick Release Double Check Valve Operational Check Leakage Test

1. Block the wheels.
2. Disconnect the air line from the balance port.
3. Start the engine.
4. Charge the air system to the air compressor governor cut-out point.
5. Stop the engine.
6. Push in the park control knob.



7. Inspect the quick release valve (double check type) exhaust port and the balance port for air leakage. Air leakage less than 25.4 mm (1 in) bubble in 5 seconds is acceptable.

If the air leakage is excessive, overhaul or replace the quick release valve (double check type).

8. Connect the air line to the balance port.
9. Pull out the park control knob.
10. Disconnect the air line from the supply port.
11. Ask an assistant to apply the brake pedal.
12. Inspect the supply port for air leakage. Air leakage less than 25.4 mm (1 in) bubble in 5 seconds is acceptable.

If the air leakage is excessive, overhaul or replace the quick release valve (double check type).

13. Inspect the seam between the body and the cover for air leakage. Leakage is not permissable. If any bubbles appear, overhaul or replace the quick release valve (double check type).
14. Connect the air line at the supply port.
15. Inspect the air lines for leaks.
16. Remove the wheel blocks.