CDL · Combination vehicles
In which situation may a parked combination vehicle be held by the trailer hand valve alone?
Correct answer: In no situation.
Answer options
- AWhen parking on a hill or grade
- BIn no situation Correct
- CWhen stopped at a loading dock
Why
The hand valve holds the trailer with air pressure, and if that air leaks away the brakes let go and the rig can roll. Always use the parking brakes when you park.
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
- After coupling to a semitrailer, how should you leave the landing gear (front trailer supports) before pulling away?
- As air pressure drops, a tractor protection valve shuts by itself at a level set by its manufacturer. That level usually falls within which range?
- Before your tractor goes under the trailer, what condition must the entire air system be in?
- Which sequence is correct for testing the trailer service brakes?
- How do you get air flowing into the trailer's air tanks?
- What must you confirm right before backing the tractor under a trailer?
- What kind of equipment are glad hands?
- During coupling, your tractor is in front of the semitrailer but not yet under it. What do you connect before backing under?
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