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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. How should you apply the brakes when going down a steep downgrade?
You should not brake, and only use engine braking to prevent brake failure.
Apply the brakes when you reach the bottom of the downgrade.
Apply the brakes whenever you reach your safe speed, until your speed has been reduced to 5 mph below your safe speed.
Apply the brakes as hard as you can without locking the wheels.
2. Air brakes are 3 different braking systems: service brake, parking brake, and _______ brake.
air storage brake
3. Most heavy vehicles require ________ change gears.
single clutching
double clutching
triple shifting
double shifting
4. You should drain the air tanks completely. If water and oil collect in the air tanks:
your brakes could heat up.
your brakes could fail.
your brakes could become hard to press.
None of the above.
5. You are coming down a long, steep downgrade. Which of the following is a sign that your brakes may have started to fade?
The steering feels heavy.
The brake pedal feels spongy or goes to the floor.
You have to apply your brakes harder and harder to get the same stopping power.
You hear a loud "bang".
6. Your mirrors should be adjusted so that:
a part of the vehicle is visible in the mirror.
more than half of the mirror shows the vehicle.
the rear of the vehicle is visible in the mirror.
no part of the vehicle is visible in the mirror.
7. Front brake limiting valves were used to:
prevent overheating of the front tires.
reduce the chance of the front wheels skidding on slippery surfaces.
reduce exhaust emissions.
reduce your speed so further braking or shifting is not required.
8. If your ABS malfunctions:
the parking brakes will not work.
you still have normal brake functions.
the service brake will not work.
you should immediately come to a complete stop.
9. If you are being tailgated, you should:
avoid quick changes.
avoid tricks like turning on your taillights or flashing your brake lights.
increase your following distance.
All of the above.
10. When you push the brake pedal down, air brakes work:
after a short delay.
after about 15 seconds.
only when ABS is working.
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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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