Home › CDL Practice Tests › Air Brakes Questions › Question 247
After coupling, how can you test that the trailer service brakes respond to the pedal?
- A.With the system charged, have a helper watch or listen at the trailer wheels while you apply the service brakes, or use the hand valve test plus a slow roll and brake check as procedures direct
- B.Drive at highway speed and make the first test in traffic
- C.Trailer brakes cannot be tested until they fail
- D.Remove a glad hand and listen for air while driving
Correct answer
A. With the system charged, have a helper watch or listen at the trailer wheels while you apply the service brakes, or use the hand valve test plus a slow roll and brake check as procedures direct
Why
Air movement and brake application at the trailer confirm the service signal reached its destination. A low-speed roll test then proves the whole combination stops straight before speed and traffic are added.
Manual topic: Air Brakes - Trailer Air Brakes · From the Air Brakes practice bank (AB-247).