Texas CDL Inspecting Air Brake Systems

Identify the compressor, governor, reservoirs, drain system, gauges, low-pressure warning, spring-brake control, service-brake control, and ABS indicators. Confirm whether the vehicle is single or combination because leakage limits and control positions differ.

With the vehicle secured, inspect hoses, tubing, chambers, slack adjusters where applicable, drums or rotors, linings or pads, mounting hardware, and air tanks. Look for abrasion, cracks, loose fittings, contamination, missing parts, and audible leaks. Brake components on the same axle must be compatible and properly adjusted.

Start with the correct test setup and watch both gauges. Verify that pressure builds at the required rate and that the compressor begins and stops pumping within the applicable operating range. Slow buildup, failure to cut in or out, or abnormal gauge differences requires service.

With the engine off and the system charged, measure pressure loss under the handbook conditions for the vehicle configuration. Then apply firm service-brake pressure and measure applied leakage. Use a timer and the current Texas testing limits; do not estimate by sound alone.

Reduce pressure in a controlled manner and verify that the low-air warning activates before pressure becomes unsafe. Continue only according to the prescribed test and confirm spring-brake or protection-system response. Never place yourself or another person in the vehicle's path during the test.

After restoring normal pressure, release the parking brakes, move slowly, and apply the service brake to confirm stopping response without pulling, delay, unusual noise, or weak braking. Any failed step means the vehicle should not be driven until inspected and repaired.