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The air brakes endorsement applies to applicants who wish to drive a vehicle with air brakes in Class A, B, or C CDL. To drive a vehicle with air brakes, you must pass the air brake component of the Vermont CDL knowledge test. The VT CDL air brakes test consists of 25 questions, and you'll need at least 20 correct answers to pass (80%). The test covers the information found in the air brakes section of the Vermont CDL Manual. Take this VT CDL practice test now to prepare for the actual air brakes test!
1. In combination vehicles with air brakes, the trailer air supply control should pop out when the air pressure falls within the range of:
10 to 20 psi
20 to 45 psi
100 to 120 psi
2. Parking brakes are:
not required on trailers.
required on all vehicles.
not required on commercial vehicles with air brakes.
3. It may not be safe to operate at legal maximum weights:
in hot weather.
during bad weather or in mountains.
on two-way streets.
4. Before driving a vehicle with a dual brake brake system, the driver should:
allow time for the air compressor to build up a minimum of 100 psi pressure in both the primary and secondary systems.
wait at least 10 minutes before driving.
pump the brake pedal 10 times to build pressure.
5. To check slack adjusters on S-cam brakes, you should:
press the brake pedal and listen for any strange noises.
use gloves and pull hard on each slack adjuster you can reach.
All of the above.
6. The total stopping distance for vehicles with air brake systems is made up of __ different factors.
7. What should you do to correct a drive-wheel braking skid?
Fully apply the brakes, turn the steering wheel quickly, push in the clutch, and countersteer.
Stop braking, turn the steering wheel quickly, push in the clutch, and countersteer.
Turn in the same direction as the skid.
8. The one-way check valve:
keeps your wheels from locking up when you brake hard.
supplies air to the trailer air tanks.
keeps air from going out if the air compressor develops a leak.
9. Air storage tanks:
use parts of the service brake systems to stop the vehicle in a brake system failure.
pump air into the air storage tanks.
hold compressed air for the brakes.
10. Most heavy vehicles require ________ change gears.
double clutching
double shifting
single clutching
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VT CDL Air Brakes Test

Number of questions: 25
Correct answers to pass:20
Passing score:80%
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