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A combination vehicle loses 5 psi in one minute during the applied-brake test. What is the correct conclusion?
- A.It passes because combinations have no limit
- B.It passes if the driver cannot hear the leak
- C.It fails the leakage standard and should not be driven until the leak is found and repaired
- D.It should be retested at highway speed
Correct answer
C. It fails the leakage standard and should not be driven until the leak is found and repaired
Why
Five psi exceeds the 4 psi per minute applied limit for combinations, so the result is a clear failure. Driving on a known excessive leak risks losing braking air faster than the compressor can replace it.
Manual topic: Air Brakes - Air Leakage and Brake Tests · From the Air Brakes practice bank (AB-077).