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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 Idaho CDL knowledge test. The ID 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 Idaho CDL Manual. Take this ID CDL practice test now to prepare for the actual air brakes test!
1. To test the service brake:
gently try to pull forward with the trailer parking brake on, then release the brake.
push the brake pedal firmly while going about 5 mph.
shift your transmission to a low gear, pump the brake pedal three times, then hold it down for five seconds.
2. You should drain your air tanks:
at the end of each working day.
at the beginning of each trip.
every month.
3. The stop light switch:
warns you when the air supply pressure drops below 55 psi.
tells you when you need to use your parking brake instead of the service brake.
turns on the brake lights when you put on the air brakes.
4. Air pressure should build up in a single air system, within about:
10 minutes.
3 minutes.
15 minutes.
5. Your vehicle has a dual air brake system. If one air system is very low on pressure, you should:
bring the vehicle to a safe stop, and have the air brakes system fixed.
reduce your speed and check the low air pressure warning signal for the other system regularly.
call your dispatcher or supervisor for instructions.
6. Which of the following is not part of the air brake system?
Air compressor
Air storage tanks
Air filter
7. If you must drive slowly, how should you alert following drivers?
Flash your brake lights
Use your emergency flashers if it is legal
Turn on your taillights
8. Supply pressure gauges tell you:
how much pressure is in the air tanks.
how much air pressure you are applying to the brakes.
when the air pressure in the tanks falls below 60 psi.
9. The heavier the vehicle:
the more work the brakes must do to stop it.
the higher the center of gravity will be.
the less work the brakes must do to stop it.
10. The __________ keeps air from going out if the air compressor develops a leak.
tractor protection valve
one-way check valve
emergency relay valve
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ID CDL Air Brakes Test

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