Home › CDL Practice Tests › Air Brakes Questions › Question 202
What can happen if trailer wheels lock during a hard stop without working ABS?
- A.The trailer will always stop in a perfectly straight line
- B.The trailer can swing out to one side, increasing jackknife or trailer-swing risk
- C.Locked trailer wheels improve stability
- D.The tractor brakes stop working automatically
Correct answer
B. The trailer can swing out to one side, increasing jackknife or trailer-swing risk
Why
A sliding trailer has little sideways grip, so small forces can push it out of line behind the tractor. Preventing trailer wheel lockup helps the whole combination stay straight during emergency braking.
Manual topic: Air Brakes - ABS · From the Air Brakes practice bank (AB-202).