During a brake test, what aspect is crucial to check?

During a brake test, it is crucial to check air pressure and response because these factors directly impact the effectiveness and safety of the air brake system. The air pressure must be within the manufacturer's specified range for the brakes to function correctly; if the pressure is too low, the brakes may not engage properly, leading to longer stopping distances or complete brake failure.

Additionally, monitoring the response of the brakes ensures that they activate promptly when the driver applies the brake pedal. A delayed response could indicate a problem within the brake system, such as leaks or component wear, which needs to be addressed before operating the vehicle. Performing this check helps ensure safety on the road by confirming that the air brake system is operating as intended.