- Updated for January 2025
- Based on 2025 NC commercial driver's license manual
Free North Carolina CDL Air Brakes Test 2025
If your career has been limited in the past by your inability to drive a commercial vehicle with air brakes, then it’s time to change that. This practice exam will help you prepare to get the air brakes restriction removed from your CDL or help you prepare to take the exam for a CDL without the air brakes restriction. These 30 multiple-choice questions were written with information directly from the North Carolina Commercial Driver’s Manual, and feature topics that the manual highlights as “need to know” for your air brake exam. By taking the exam as often as necessary until you are comfortable, and reading each question’s explanation so you fully understand the subject, you should be ready to handle the real CDL air brakes exam with ease. So good luck now, and on your future CDL air brakes exam!
- Perfect for first-time and renewal CDL/CLP applicants, and those adding endorsements
- Triple-checked for accuracy
What you need to know
What to expect on the actual NC DMV exam
questions
correct answers to pass
passing score
Helpful links
List of questions (classic view)
- Under which conditions are front wheel brakes good?
- When should you use the parking brake?
- The purpose of a supply pressure gauge is
- What is the best way to test your vehicle's low air pressure warning signal?
- The tractor protection valve
- How can you tell if your vehicle is equipped with an antilock braking system (ABS)?
- Which of the following should you do before leaving your vehicle unattended?
- How would you check your truck's slack adjusters?
- Slack adjusters are
- Which of the following is NOT part of the air brake system?
- Which of the following will be true about your brake function if your antilock braking system (ABS) fails?
- At what measurement is the safety valve USUALLY set to open?
- An antilock braking system (ABS)
- Which of the following can cause brakes to fade or fail?
- Which of the following are true about a dual air brake system?
- Which of the following is NOT part of the braking process when you're driving a tractor-trailer combination vehicle with an antilock braking system (ABS)?
- When should you drain your air tanks?
- After the initial drop, the maximum acceptable leakage rates per minute are
- What is the best way to test if your vehicle's spring brakes come on automatically?
- Spring brakes are
- How do brakes work on a long, steep downgrade?
- Which of the following is NOT part of the drum brake?
- If the air tanks are not drained,
- Which vehicles must have low air pressure warning signals?
- Why must you pass a knowledge test on air brakes?
- The low air pressure warning signal will come on before the pressure in the air tanks falls below
- A low pressure warning signal is required on
- All vehicles equipped with air brakes have
- With air brake-equipped vehicles, the parking brakes should be used
- The use of air brakes on a downgrade is only a supplement to the
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