CDL · Doubles and triples
To test the trailer brakes, you apply the hand valve and open the valve on the service line at the very rear of the combination. What sound should you hear?
Correct answer: Air rushing out of the opened valve.
Answer options
- AThe valve on the emergency line opening and releasing air
- BThe service brakes gradually going into full application
- CAir rushing out of the opened valve Correct
Why
Air hissing out of the valve at the back confirms that service air is reaching every trailer. If no air comes out, make sure the shut-off valves on the other trailers and dollies are open, because air must reach the back for all the brakes to work.
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 Inspecting Doubles and Triples (15 questions). Take the full set and check your score.
Practice Inspecting Doubles and TriplesMore questions from Inspecting Doubles and Triples
- How do you confirm that air is reaching every trailer in a double or triple combination?
- What is the reason a rig with two or three trailers needs a more careful inspection than one pulling a single semitrailer?
- On a walk-around inspection, what should be true of every landing gear?
- When you inspect a doubles or triples rig on your walk-around, in what state should you find the air tank drain valves on the converter dolly and the pintle hook?
- You are inspecting a converter dolly. What must be true of its pintle hook connection?
- You are doing a pre-trip inspection on a set of doubles or triples. How should the drain valve on the converter dolly's air tank be set?
- Which of these is a key check when you inspect a double or triple rig?
- In a double or triple combination, how should you set the shut-off valves located at the back of the rearmost trailer?
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