Home › CDL Practice Tests › Air Brakes Questions › Question 37
Why must air tanks be drained regularly, ideally daily?
- A.Draining raises the governor cut-out pressure
- B.Draining is only needed to make room for fuel vapor
- C.Water and oil collect in the tanks and can freeze, corrode parts, or reduce tank capacity
- D.Water in the tanks improves braking in winter
Correct answer
C. Water and oil collect in the tanks and can freeze, corrode parts, or reduce tank capacity
Why
Compressor output carries water vapor and a little oil that condense inside the tanks. Draining the wet tank first, and fully opening the valves, prevents freeze-ups that can block air flow and disable brakes in cold weather.
Manual topic: Air Brakes - Air Tanks and Drains · From the Air Brakes practice bank (AB-037).