CDL General Knowledge TestAir Brakes (if applicable)Easy
A driver notices that the air pressure gauge shows a rapid drop in pressure when the service brakes are applied repeatedly. The low air warning light and buzzer activate almost immediately after a few brake applications. What does this most likely indicate?
- AA clogged air dryer filter.
- BA faulty air compressor governor.
- CNormal operation for a dual air brake system.
- DExcessive air loss in the service brake system.
Show answer & explanationAnswer & explanation
Correct answer: D. Excessive air loss in the service brake system.
A rapid drop in air pressure accompanied by the low air warning light and buzzer when applying the service brakes points to a significant leak in the service brake system. This means the system is losing air faster than the compressor can replenish it.
Why the other options are wrong
- A. A clogged air dryer would primarily affect moisture removal and air pressure build-up, not rapid loss during brake application.
- B. A faulty governor would affect when the compressor cuts in or out, not necessarily cause rapid pressure loss on brake application.
- C. This is not normal operation; rapid pressure drop and low air warnings indicate a serious malfunction.
Excessive Air Loss (Service Brakes)
A condition where the air brake system loses air pressure too quickly when the service brakes are applied, often due to a significant leak.
- Indicated by rapid pressure drop on gauge.
- Low air warning light and buzzer activate quickly.
- Requires immediate attention and repair.
Memory trick: Rapid air loss means a big brake system flaw, requiring immediate attention.