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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 Maryland CDL knowledge test. The MD 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 Maryland CDL Manual. Take this MD CDL practice test now to prepare for the actual air brakes test!
1. To test the low pressure warning signal, you should:
pump the brakes while your vehicle is running.
check the air hoses connected to the brake chambers to make sure they aren't cut.
shut the engine off when you have enough air pressure, turn the electrical power on and step on and off the brake pedal until the low air pressure warning signal comes on.
manually let the air out of your brakes and see if the signal comes on.
2. As part of the final air brake check, you should:
Test air leakage rate.
Check air compressor governor cut-in and cut-out pressure.
Test low pressure warning signal.
All of the above.
3. The alcohol evaporator:
ensures the coolant temperature gauge remains in the normal range.
helps to reduce the risk of ice in air brake valves and other parts in cold weather.
eliminates the need for daily air tank drainage.
shows how much air pressure you are applying to the brakes.
4. How do you test hydraulic brakes for leaks?
Pump the brake pedal ten times and see if it holds.
Pull forward against parking brake to make sure the hydraulic brakes holds.
Pump the brake pedal three times, then apply firm pressure to the pedal and hold for five seconds. The pedal should not move.
None of the above.
5. You should drain the air tanks completely. If water and oil collect in the air tanks:
your brakes could fail.
your brakes could become hard to press.
your brakes could heat up.
None of the above.
6. If you must stop on a one-way or divided highway, place your warning devices:
50 feet, 100 feet, and 150 feet toward the approaching traffic.
10 feet, 50 feet, and 150 feet toward the approaching traffic.
10 feet, 100 feet, and 200 feet toward the approaching traffic.
100 feet, 200 feet, and 300 feet toward the approaching traffic.
7. The best way to recognize that your trailer has started to skid is:
by opening the window and feeling the front of the mirror.
by recognizing tire failure.
by feeling the brakes come on.
by seeing it in your mirrors.
8. Spring brakes:
are not designed to work in an emergency when your service brakes fail.
are air applied like service brakes.
apply when air pressure leaves the brake chamber and release when air pressure builds up in the chamber.
All of the above.
9. After a tire has been changed, the driver should stop a short while later to:
check the tightness of the nuts.
check tread separation.
decrease tire pressure.
deflate the tire to 10 psi.
10. The air compressor is connected to:
the transmission.
the suspension system.
the radiator.
the engine.
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MD CDL Air Brakes Test

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