Home › CDL Practice Tests › Air Brakes Questions › Question 41
About how long should it take for air pressure to build from 85 to 100 psi at normal operating RPM during a proper test?
- A.Within 45 seconds (for typical dual systems tested at 1,000 to 1,200 rpm)
- B.Within 5 minutes
- C.Within 10 seconds on every vehicle regardless of size
- D.There is no time standard for the build-up test
Correct answer
A. Within 45 seconds (for typical dual systems tested at 1,000 to 1,200 rpm)
Why
The build-up test proves the compressor can outpace normal use and refill the tanks promptly. A slow build points to a worn compressor, a leak, or a governor problem that must be found before the trip.
Manual topic: Air Brakes - Air Compressor and Governor · From the Air Brakes practice bank (AB-041).