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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 Delaware CDL knowledge test. The DE 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 Delaware CDL Manual. Take this DE CDL practice test now to prepare for the actual air brakes test!
1. When driving on slippery roads, you should NOT:
try to anticipate stops early.
go slowly.
watch far enough ahead to keep a steady speed.
use the engine brake.
2. When should you be particularly careful about high winds?
When driving in winter
When emerging from a tunnel
When going downhill
When driving at night
3. To check the slack adjusters on S-cam brakes, you should:
park on level ground, chock the wheels and release the parking brakes, then use gloves and pull hard on each slack adjuster that you can reach.
release the parking brake valve and begin reducing the air pressure by stepping on and off the brake pedal.
park on level ground and fan off the air pressure by rapidly applying and releasing the foot brake.
All of the above.
4. What is a dual air brake system?
2 separate air brake systems: one system operates the left brakes, the other system operates the right brakes.
2 separate air brake systems: one system for daytime driving, the other system for nighttime driving.
2 separate air brake systems: one system operates the front brakes, the other system operates the rear brakes.
None of the above.
5. If your vehicle is equipped with a front brake limiting valve, to ensure normal stopping power make sure the control is:
in the "slippery" position.
in the "neutral" position.
in the "normal" position.
in the "off" position.
6. With brake drums, if brakes become too hot:
the air compressor will kick on to cool the brakes.
the brakes may stop working.
your ABS will malfunction.
the brakes will supply too much power to the drive wheels.
7. The one-way check valve:
keeps the axles in place.
keeps air from going out if the air compressor develops a leak.
keeps your wheels from locking up when you brake hard.
supplies air to the trailer air tanks.
8. The air brake lag distance at 55 mph on dry pavement adds about:
16 feet.
75 feet.
32 feet.
60 feet.
9. The air compressor governor:
controls when the air storage tanks will pump air into the air compressor.
stops the compressor from pumping air.
allows the compressor to start pumping air when the tank pressure rises to the "cut-out" pressure.
All of the above.
10. If the low pressure warning signal doesn't work:
this could cause sudden emergency braking in a single-circuit air system.
in dual systems the stopping distance will be decreased.
you could lose air pressure and you would know it.
None of the above.
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DE CDL Air Brakes Test

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