Home › CDL Practice Tests › Air Brakes Questions › Question 88
If air pressure builds normally but falls rapidly whenever the service brakes are applied repeatedly in traffic, what is a likely cause?
- A.The brake drums are too cold
- B.Air is being used or lost faster than the compressor can replace it, from a leak, excessive applications, or both
- C.The governor cut-out is set too high
- D.The fuel filter is restricted
Correct answer
B. Air is being used or lost faster than the compressor can replace it, from a leak, excessive applications, or both
Why
Repeated applications are the heaviest air demand the system faces, so a marginal leak shows up there first. The driver should stop overusing the brakes, use engine braking on grades, and have the leak repaired.
Manual topic: Air Brakes - Air Leakage and Brake Tests · From the Air Brakes practice bank (AB-088).