CDL · Combination vehicles
While your combination vehicle is moving, its service air line pulls apart, yet the emergency line holds. What is the immediate effect?
Correct answer: Most likely nothing, until you put on the brakes.
Answer options
- AMost likely nothing, until you put on the brakes Correct
- BThe tractor's emergency brakes will apply immediately
- CAir will rush out of the trailer tank through the open line
Why
The service line carries air only when the brakes are applied, so a break in it goes unnoticed at first. Once you brake, air escapes through the open line, tank pressure drops, and the trailer emergency brakes may come on.
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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- You are testing the tractor protection valve. Which result shows that the valve is working properly?
- For a secure coupling, the fifth wheel jaws must grip which section of the kingpin?
- 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?
- When you look over a fifth-wheel coupling after hooking up, what should you see?
- The fifth wheel jaws have closed on the kingpin, but the locking lever is not in the locked position. What does this tell you?
- How do you test whether the tractor and semitrailer are securely coupled?
- When you park a tank trailer, what should hold it in place?
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