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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 Ohio CDL knowledge test. The OH 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 Ohio CDL Manual. Take this OH CDL practice test now to prepare for the actual air brakes test!
1. If your vehicle is equipped with air brakes, loss of air pressure in the emergency line causes:
the trailer emergency brakes to come on.
the speed of your vehicle to increase.
the trailer spring brakes to come on.
2. The air compressor stops pumping air into the air storage tanks when air tank pressure rises to around:
100 psi.
450 psi.
125 psi.
3. Some air brake systems have an alcohol evaporator to:
prevent ice from forming in the brake system.
reduce the stopping power of the vehicle.
reduce the danger of slipping.
4. When driving in a construction zone, if a construction worker is near the road, you should:
come to a complete stop.
maintain a constant speed.
further reduce your speed.
5. The ______ puts alcohol into the air system.
alcohol tank drains
alcohol evaporator
air tank drains
6. Which of the following is a reason why air tanks must be drained?
Your brakes may fail due to the water freezing.
Your battery fluid may drain out.
The governor may stop the compressor from pumping air.
7. In vehicles with air brakes, the two markings on a front brake limiting valve are:
left and right.
high and low.
normal and slippery.
8. If your ABS malfunctions:
you still have normal brake functions.
you should immediately come to a complete stop.
the service brake will not work.
9. Which of the following is not part of the air brake system?
Air filter
Air compressor
Air storage tanks
10. Perception Distance + Reaction Distance + Brake Lag Distance + Braking Distance = ?
Total Stopping Distance
Total Air Pressure
Stopping Distance - (minus) Brake Fade Distance
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OH CDL Air Brakes Test

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