CDL · Combination vehicles
During ordinary driving, some truckers apply the trailer hand valve ahead of the foot brake, believing it prevents jackknifing. Which statement about this habit is correct?
Correct answer: It is a habit drivers should not follow.
Answer options
- AIt causes fewer skids than braking with the pedal by itself
- BIt is a habit drivers should not follow Correct
- CIt is the most effective way to stop with the rig in a straight line
Why
Using the hand valve while driving can lock the trailer wheels and make the trailer skid, which is how a jackknife begins. The brake pedal sends air to the brakes on every unit at once, so use it for normal stops and save the hand valve for testing the trailer brakes.
About this question
Topic: Combination vehicles License: CDL
Part of these practice sets:
Where it applies: Asked in every state.
Practice the whole set
This question is part of Trailer Air Lines and Coupling (28 questions). Take the full set and check your score.
Practice Trailer Air Lines and CouplingMore questions from Trailer Air Lines and Coupling
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