Home › CDL Practice Tests › Combination Vehicles Questions › Question 14
After connecting the air lines, what should you check before moving?
- A.Only that the hoses look new
- B.That air is reaching the trailer, there are no major leaks, and the trailer brakes apply and release
- C.That the hoses hang as low as possible
- D.That the supply knob stays pushed in with the engine off
Correct answer
B. That air is reaching the trailer, there are no major leaks, and the trailer brakes apply and release
Why
Air in the trailer reservoirs is what lets its brakes work and its spring brakes release. Listening for leaks and testing brake response confirms the trailer system is charged and functional.
Manual topic: Combination Vehicles - Coupling · From the Combination Vehicles practice bank (CV-014).