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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 Oklahoma CDL knowledge test. The OK 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 Oklahoma CDL Manual. Take this OK CDL practice test now to prepare for the actual air brakes test!
1. The space under a heavily loaded vehicle can be very small. This can cause problems:
on dirt roads.
when crossing railroad tracks.
All of the above.
2. Some air brake systems have an alcohol evaporator. Checking the alcohol container and filling it up as necessary:
reduces the risk of ice in air brake valves during cold weather.
helps keep the engine cool, as well as lubricating it.
helps you avoid wheel lock up.
3. If the drive wheels begin to spin when accelerating, you should:
continue to accelerate.
brake gently.
take your foot off the accelerator.
4. An alcohol evaporator:
is used to reduce the risk of ice in air brake valves and other parts during cold weather.
protects the air brake system from too much pressure.
used to reduce the chance of the front wheels skidding.
5. You must take the CDL skills tests in the type of vehicle for which you wish to be licensed. If your test vehicle does not have air brakes:
you'll need to take another knowledge test about air brakes.
you'll have to immediately retake your test using another vehicle.
you will be restricted to driving vehicles without air brakes.
6. Why must air tanks be drained?
Water can freeze in cold weather and cause brake failure.
Water and oil reduce the air pressure.
To keep from fouling the air compressor oil.
7. ABS:
allows you to brake harder.
should only be used on dry roads.
is an addition to your normal brakes.
8. During a trip you should check:
pressure gauges.
temperature gauges.
All of the above.
9. Older trailers do not have spring brakes. If the air supply leaks away:
the ABS won't work properly.
there will be no emergency brakes.
the trailer will stop normally.
10. If a vehicle is equipped with ABS, when you start the engine:
the ABS indicator light on the dash should come on and then turn off.
the spring brakes will come on.
the wheels will lock up.
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OK CDL Air Brakes Test

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