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What does the air pressure gauge tell the driver on an air-brake vehicle, and what range signals a problem?
- A.It shows tire pressure
- B.It shows reservoir pressure; driving with pressure below the normal governed range, or watching it fall instead of build, signals a leak or compressor problem
- C.Low air only affects the horn
- D.Air pressure rebuilds instantly after any loss
Correct answer
B. It shows reservoir pressure; driving with pressure below the normal governed range, or watching it fall instead of build, signals a leak or compressor problem
Why
The gauge confirms the compressor is keeping up with brake use and leakage. A needle that will not reach the normal cut-out range, roughly 120 to 125 psi on many systems, or that drops quickly at a stop, is an inspection finding, not a quirk to live with.
Manual topic: Gauges - Air Pressure · From the General Knowledge practice bank (GK-366).