CDL · Doubles and triples
How can you release the brakes on a converter dolly?
Correct answer: Drain the dolly's air tank through its petcock.
Answer options
- ADrain the dolly's air tank through its petcock. Correct
- BRelease the pintle hook on the lead trailer.
- CTrip the tractor protection valve from the cab.
Why
Letting the air out of the dolly's tank through its petcock releases the dolly brakes. If the dolly has spring brakes, you use its parking brake control instead.
About this question
Topic: Doubles and triples License: CDL
Part of these practice sets:
Where it applies: Asked in every state.
Practice the whole set
This question is part of Coupling Doubles and Converter Dollies (28 questions). Take the full set and check your score.
Practice Coupling Doubles and Converter DolliesMore questions from Coupling Doubles and Converter Dollies
- On a set of doubles, where should the rear trailer's landing gear be while you test the coupling?
- Once the converter dolly is hooked to the rear trailer, you check the connection by eye. How much of a gap should there be where the upper fifth wheel meets the lower one?
- The second trailer you need to couple has no spring brakes, and you have no wheel chocks. What should you do before you couple it?
- Your set of twins includes a loaded rear trailer that you are about to unhook. How low should its landing gear go?
- You have backed the converter dolly under the rear trailer of a double and are about to check the coupling. How should that trailer's landing gear be positioned?
- What are the basic components of a converter dolly?
- You release the pintle hook before the converter dolly has been pulled out from under the second trailer. What is the likely result?
- What is unique about the way triple trailers are coupled?
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