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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 North Carolina CDL knowledge test. The NC 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 North Carolina CDL Manual. Take this NC CDL practice test now to prepare for the actual air brakes test!
1. Some vehicles have a separate air tank which can be used to:
release the spring brakes.
unload cargo or passengers.
hold the vehicle or combination of vehicles stationary.
turn on the 4-way emergency flashers.
2. Controlled braking:
involves pumping the brakes while keeping steering wheel movements very small.
must be used when you need to turn sharply while braking.
involves locking the wheels and then releasing the brakes.
can be used to keep your vehicle in a straight line and allow you to turn if necessary.
3. If you are being tailgated, you should:
drive on the shoulder.
speed up.
turn on your taillights.
try to let the other vehicle pass.
4. A low air pressure warning signal must come on when the air pressure in the tanks falls below:
15 psi.
60 psi.
100 psi.
10 psi.
5. How can you tell if your vehicle is equipped with ABS (anti-lock braking system)?
ABS is required on all vehicles manufactured on or after 2005.
There is no way to tell, ABS is still optional on all vehicle types.
ABS is required on all vehicles manufactured on or after 2000.
Trucks, buses, trailers, and converter dollies built after 1998 are required to have ABS.
6. When a tire fails, you must:
stay off the brake.
hold the steering wheel firmly.
get out and check all the tires after you have come to a stop.
All of the above.
7. In newer vehicles with air brakes, you put on the parking brake:
using a diamond-shaped, yellow, push-pull control knob.
placing the transmission in Park.
moving the orange push-pull lever to the right.
using a P-shaped, yellow control knob.
8. Which of the following is not a way to know when to change gears?
Use road speed (mph)
Check that the pressure gauge shows normal oil pressure
Watch your tachometer
Use engine speed (rpm)
9. Vehicles with air brake systems take longer to come to a complete stop than vehicles with hydraulic brakes because of:
brake fading.
reaction distance.
tire pressure.
brake lag.
10. The emergency brake system:
uses parts of the service and parking brake systems to stop the vehicle in the event of a brake system failure.
uses the service brake to stop the vehicle in the event of a parking brake system failure.
uses the parking brake to stop the vehicle in the event of a brake system failure.
None of the above.
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NC Air Brakes CDL Test

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