A guide to performing Air Brake Checks
- Performing Tug Tests
Tug against parking brake only. Tug against emergency brake only. Test Service brake by accelerating to 5 mph and pressing the brake pedal. If the vehicle pulls to one side, this indicates a brake alignment problem. - EngineOn / Brakes On
Checking the air pressure gauges to make sure they are rising to governor cut off or 120 PSI to 140 PSI. Governor cut off happened at xx PSI. - Engine Off / Key On
Push in brake valves and after initial drop, I’ll hold my brake pedal for 1 minute and should lose no more than 3 PSI for a B truck and 4 PSI for an A truck. (This portion of the air brake test is checking for leaks as if you were stopped at a light with your foot on the brake). - Key Still On / Engine Still Off / Brake Still Off
I will pump my brakes until the pressure drops. Warning: the low air warning device should sound and/or appear on dash at, or above 55 PSI. My warning light and buzzer came on at 55 PSI. - Continue Pumping the brakes to between 20 and 40 PSI where the brake valves should pop out applying the brakes. My brake valves popped at xx PSI.
If there is a problem discovered while testing the Air Brakes, do not drive the vehicle. It is your responsibility to make sure it is repaired by a mechanic. Never operate a vehicle that is unsafe to drive.