Home › CDL Practice Tests › Combination Vehicles Questions › Question 1
Before backing under a trailer, what should you first check about the trailer's height?
- A.It is as high as the landing gear will raise it
- B.It is lower than the top of the tractor tires
- C.Height does not matter if you back slowly
- D.It is high enough for the tractor to back under, but low enough for the kingpin to engage the fifth wheel correctly
Correct answer
D. It is high enough for the tractor to back under, but low enough for the kingpin to engage the fifth wheel correctly
Why
Trailer height determines whether the kingpin meets the fifth wheel at the right point. Too high can miss the jaws or damage the kingpin, and too low can strike the tractor frame or tires.
Manual topic: Combination Vehicles - Coupling · From the Combination Vehicles practice bank (CV-001).