How do you confirm that air is reaching every trailer in a double or triple combination?
Correct answer: With the system charged, open the emergency line's shut-off valve at the back of the last trailer, listen for air, then repeat with the service line.
Answer options
- AWith the system charged, open the emergency line's shut-off valve at the back of the last trailer, listen for air, then repeat with the service line Correct
- BFrom the cab, push in the parking brake knob and make sure it stays in for several minutes, which proves air is reaching every trailer
- CDrive at highway speed with all the trailers loaded and listen closely for any change in engine sound that would point to low air pressure
Why
Air rushing out at the very end of the rig, first from the emergency line and then from the service line, proves both lines carry air through every trailer and dolly. If you hear nothing, make sure the shut-off valves on the trailers and dollies ahead are open.
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
- On a walk-around inspection, what should be true of every landing gear?
- 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?
- You are inspecting a converter dolly. What must be true of its pintle hook connection?
- What is the reason a rig with two or three trailers needs a more careful inspection than one pulling a single semitrailer?
- Which of these is a key check when you inspect a double or triple rig?
- 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?
- In a double or triple combination, how should you set the shut-off valves located at the back of the rearmost trailer?
- 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?
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