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MB Air Brake Test 8 2025

Based on the 2025 MB CDL manual
Questions: 50
Mistakes allowed: 10
Passing score: 80%
Ensuring the accuracy and quality of our practice tests is paramount. Learn more about our rigorous standards in our Commitment to Accuracy article.

Air brakes are an integral part of commercial vehicles, requiring a deep understanding of their operations and safety features. Keep your preparation momentum going with this 50-question practice test based on the 2025 MB commercial driver’s manual. Questions range from basic functionalities to emergency procedures, and each comes with a detailed explanation to deepen your grasp of air brake systems. Your Air Brake endorsement is not far away; let’s get it!

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Based on 2025 MB commercial driver's license manual
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List of questions (classic view)
  1. If a vehicle's weight is doubled, the braking distance is...
  2. Why is it recommended to inspect the air brake systems on a flat surface?
  3. What happens when there is an abnormal drop in wheel speed in an ABS-equipped vehicle?
  4. According to the Highway Traffic Act, what is the minimum frequency for checking vehicles with air brakes?
  5. To slow down on long downgrades without overusing the service brakes, tractor-trailers may use any of these EXCEPT
  6. In vehicles with ABS, where are the warning lights or malfunction lamps typically located?
  7. If your vehicle's weight is increased by a heavy load, what is NOT likely to happen?
  8. If both the vehicle's weight and speed are doubled, by how much is the braking distance increased?
  9. Do anti-lock brake systems (ABS) decrease stopping distances?
  10. What is the primary benefit of having anti-lock brakes?
  11. Which condition does not cause the operating temperature of the brakes to increase more than normal?
  12. Which component is NOT external to the s-cam foundation brake?
  13. During brake inspections, what are drivers not necessarily expected to identify about brake components?
  14. What component does not cover part of the rotor in an air disc brake?
  15. What is the consequences of excessive pushrod stroke?
  16. Which of these factors does not impact how your vehicle's brakes work?
  17. When should the brake-shoe lining be in contact with the brake drum?
  18. How is the functioning status of an anti-lock braking system indicated in a vehicle?
  19. Why must wheel chocks or blocks be utilized during air brake inspections?
  20. If a wheel seal is leaking, where might some of the lubricant end up?
  21. What is the primary purpose of an air brake system inspection?
  22. Can a vehicle with a defective air brake system legally be operated on any road or highway?
  23. What do brakes convert the energy of a moving vehicle into?
  24. If a vehicle is operated with defects or without the required inspections, it can result in all of the following EXCEPT
  25. Under normal driving conditions on clean dry roads, how can you identify if a vehicle has anti-lock brakes?
  26. When the speed of a vehicle is doubled, the stopping distance is...
  27. Does brake imbalance influence the vehicle's ability to steer?
  28. Which air brake components are most susceptible to damage?
  29. What is the principal method for identifying air leaks in the air brake chamber?
  30. In a governor test, the cut-in pressure setting is usually how many psi below the cut-out pressure setting?
  31. Should each brake at both ends of an axle have equal-sized air brake chambers to ensure balanced braking forces?
  32. Most low air pressure warning devices activate when the pressure falls to
  33. If a vehicle fails the air pressure build-up time test, when should it be reported to the operator and repaired?
  34. Before conducting the air-pressure build-up time test, the air pressure should be reduced to
  35. The air brake system fails the air pressure build-up time test if the build-up time exceeds
  36. At what psi is the air brake system deemed flawed if the cut-in pressure drops below this level?
  37. Which of these is incorrect? An air brake chamber inspection checks for
  38. Which of these inspections does not include the vehicle's air compressor?
  39. There is often a noticeable change in the behaviour of brakes with drums or rotors that are...
  40. The air compressor belt is NOT necessarily defective if the belt is
  41. To ensure balanced braking, slack adjusters on each end of an axle should be...
  42. When you inspect the air lines during the pre-trip inspection, what should you look for?
  43. To test the air pressure build-up time, what should be the idling speed of the engine?
  44. What psi should the pressure be above when you start testing the low air-pressure warning device?
  45. What is the maximum allowable air loss when testing system air-loss for a straight truck, tractor, or bus?
  46. The cut-out pressure must not be lower than how much psi?
  47. For testing the air pressure build-up time, what pressure range should you observe?
  48. The cut-out pressure must not exceed what psi?
  49. What's the aftermath if the vehicle fails the low air-pressure warning test?
  50. What is checked during an inspection of a vehicle's air tanks?