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  • Updated for November 2024
  • Based on 2024 IL commercial driver's license manual

Free Illinois CDL Air Brakes Test 2024

Today, your knowledge of air brakes will be tested. THis will help you do better on your upcoming DMV air brake exam. The 30 multiple-choice questions included are based on information from the Illinois Commercial Drivers License Study Guide, and are meant to closely simulate the exact types of questions you will find on your DMV exam. Read each question as well as the accompanying answer explanation carefully, so that you will be prepared if the exam asks about these topics in a different manner. Keep practicing, good luck, and drive safely!

  • Perfect for first-time and renewal CDL/CLP applicants, and those adding endorsements

What you need to know

9 min to complete
Available in EN and ES
Verified by Steven Litvintchouk, M.S., Chief Educational Researcher, Member of ACES. See our detailed commitment to accuracy and quality in our practice tests.

What to expect on the actual IL DMV exam

25

questions

20

correct answers to pass

80%

passing score

List of questions (classic view)

  1. Which of the following are true about a dual air brake system?
  2. At what measurement is the safety valve USUALLY set to open?
  3. Slack adjusters are
  4. The tractor protection valve
  5. Which of the following is NOT part of the air brake system?
  6. How do brakes work on a long, steep downgrade?
  7. Which of the following can cause brakes to fail or fade?
  8. Why must you study air brakes in the state of Illinois?
  9. Which of the following is NOT part of the braking process when driving a tractor-trailer combination vehicle with an anti-lock braking system (ABS)?
  10. When should you use the parking brake?
  11. What is the best way to test your vehicle's low air pressure warning signal?
  12. What is the best way to test if your vehicle's spring brakes come on automatically?
  13. Which of the following should you do before leaving your vehicle unattended?
  14. The purpose of a supply pressure gauge is
  15. How would you check your truck's slack adjusters?
  16. After the initial drop, the maximum acceptable leakage rates per minute are
  17. Which of the following will be true about your brake function if your anti-lock braking system (ABS) fails?
  18. If the air tanks are not drained,
  19. How can you tell if your vehicle is equipped with an anti-lock braking system (ABS)?
  20. Which of the following is NOT part of the drum brake?
  21. When should you drain your air tanks?
  22. Spring brakes are
  23. An anti-lock braking system (ABS)
  24. Which vehicles must have low air pressure warning signals?
  25. Under which conditions are front wheel brakes good?
  26. The low air pressure warning signal will come on before the pressure in the air tanks falls below
  27. A low pressure warning signal is required on
  28. All vehicles equipped with air brakes have
  29. With air brake-equipped vehicles, the parking brakes should be used
  30. The use of air brakes on a downgrade is only a supplement to the
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