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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 South Carolina CDL knowledge test. The SC 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 South Carolina CDL Manual. Take this SC CDL practice test now to prepare for the actual air brakes test!
1. Do NOT use the parking brakes:
when you leave your vehicle.
if the brakes are very hot.
to test that they work.
when you park for less than two hours.
2. You hear a loud "bang" which sounds like a tire blowout. You should:
inspect your tires with your mirrors.
check the tires at the next stop.
keep driving as normal.
assume you have a tire failure.
3. If the air pressure gets too low:
the brakes will not work.
ABS will help maintain vehicle control.
you should set the parking brake.
the brakes will lock up.
4. Empty trucks have the best braking. True or False?
It depends on the truck.
It depends on the cargo.
5. If the air compressor is belt-driven, you should check the air compressor drive belt before each trip. The belt should be:
6. The alcohol evaporator:
ensures the coolant temperature gauge remains in the normal range.
shows how much air pressure you are applying to the brakes.
eliminates the need for daily air tank drainage.
helps to reduce the risk of ice in air brake valves and other parts in cold weather.
7. If you're feeling tired while driving you should:
drink coffee.
eat something.
increase your speed to get to your destination quicker.
stop driving and get some rest.
8. The air tanks should be drained completely to remove:
carbon monoxide.
water and oil.
the radiator cap.
9. To perform an applied leakage test, the vehicle’s air pressure should be built up to maximum pressure. Check the air gauge to see that the air pressure should drop no more than:
3 psi for single vehicles and 4 psi for a combination of 2 vehicles.
5 psi for single vehicles and 6 psi for a combination of 2 vehicles.
2 psi for single vehicles and 5 psi for a combination of 2 vehicles.
1 psi for single vehicles and 3 psi for a combination of 2 vehicles.
10. If a vehicle is equipped with ABS, when you start the engine:
the spring brakes will come on.
the wheels will lock up.
the trailer emergency brakes will come on.
the ABS indicator light on the dash should come on and then turn off.
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SC CDL Air Brakes Test

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