How to Test Air Brakes

If air makes its way into your brake line, your brakes could lose their effectiveness and become hazardous. The best way to keep your vehicle safe and avoid an accident is to test the air brake system regularly.

Instructions

1

Examine all equipment when testing air brakes, including drums and discs, hoses and chambers, slack adjusters and actuators, relay valves, tanks, pipes and fittings.

2

Check that all the brake components, including the air compressor drive belt, are secure. They shouldn't be weakened, worn or damaged.

3

Verify that there is a compressor air filter and operational visible brake failure indicators when you test air brakes.

4

Look for slack adjusters that travel too far when brakes are applied.

5

Inspect the compressor hoses and fittings, drive belt and pulley for excessive wear, cracks and tightness.

6

Test the rate of air leakage by shutting down the engine with a fully-charged air system. Release the service brake and allow the air system to settle. Time the air pressure drops and record the loss rate. If that rate exceeds the recommended p.s.i. pounds per square inch), look for air leaks and repair them.

7

Build up normal air pressure and depress the air supply knob. Turn the engine off. Reduce the air pressure by depressing the brakes a few times.

8

Confirm the service brakes are working properly. Attain normal air pressure and discharge the parking brake. Move forward at about 5 mph and firmly depress the brake pedal. Check the brakes if your vehicle pulls to either side, have a strange feel or a slow stopping action.