CDL Air Brakes TestAir Brake System PartsMedium
A commercial vehicle driver is performing a pre-trip inspection. After charging the system, they notice that the air compressor cycles on and off more frequently than usual, even when no brakes are being applied. What does this symptom most likely indicate?
- AThe air compressor governor is set too high.
- BThere is a continuous air leak in the system.
- CThe air storage tanks are overfilled with moisture.
- DThe air dryer is malfunctioning and causing back pressure.
Show answer & explanationAnswer & explanation
Correct answer: B. There is a continuous air leak in the system.
If the air compressor cycles on and off more frequently than usual without brake application, it indicates that the system is losing air pressure faster than it should. This is a classic sign of a continuous air leak somewhere in the air brake system.
Why the other options are wrong
- A. A governor set too high would cause the compressor to build to a higher pressure before cutting out, but wouldn't necessarily cause frequent cycling unless there was also a leak.
- C. Overfilled air tanks with moisture would primarily affect brake performance and system component longevity, not directly cause frequent compressor cycling without a pressure loss.
- D. A malfunctioning air dryer causing back pressure might affect compressor efficiency but wouldn't typically cause frequent cycling unless the back pressure was so severe it mimicked a leak.
Continuous Air Leak Symptom
Frequent cycling of the air compressor without brake application is a key symptom of a continuous air leak within the air brake system, as the compressor works harder to maintain lost pressure.
- Indicates pressure loss in the system.
- Can be internal or external leak.
- Requires immediate investigation and repair.
Memory trick: Compressor's working hard? A hidden leak is playing its card!