What is the purpose of the trailer air supply control?
Answer: A
To control the tractor protection valve
The trailer air supply control controls the tractor protection valve while supplying the trailer with air pressure.
Source: Alaska CDL Manual
All choices
- ATo control the tractor protection valve
- BTo control air compressor governor cut-in and cut-out
- CThe control brake relay valves for the tractor brakes
Why the other answers are wrong
B. To control air compressor governor cut-in and cut-out
The trailer air supply control does not regulate the air compressor governor.
C. The control brake relay valves for the tractor brakes
It does not control the brake relay valves for the tractor brakes.
Alaska CDL Combination Vehicles Test Info
Questions on Exam
20
Passing Score
80%
Time Limit
Typically 30 minutes; varies by testing location
Age Requirements
Intrastate: 18+ · Interstate: 21+
Alaska Division of Motor Vehicles
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More CDL Combination Vehicles Practice Questions
- Glad hands are usually connecting which of these?
- Why should you lock the tractor glad hands to each other (or dummy couplers) when you are not towing a trailer?
- After connecting the air lines but before backing under the trailer you should:
- The crack-the-whip effect is related to:
- Sudden turns or aggressive braking will have the greatest effect on which trailer?