MB Air Brake Test 4 2025

1. How often should the air tanks be drained?
2. On a tractor-trailer, if the supply and service lines to the trailer are cross-connected, what may happen?
3. How do you release DD3 safety actuator brakes?
4. When you're going to tow a trailer, how can you tell if the trailer's antilock braking system (ABS) is working?
5. Wedge brakes are
6. The purpose of the tractor protection valve is
7. To test the tractor protection valve, disconnect the trailer service line and
8. In a tractor-trailer, the connections between the tractor and the trailer include which of the following components?
9. The hand valve control ("spike") applies
10. Which brakes are more powerful, the spring brakes or the service brakes?
11. Which of the following is NOT a part of a truck's braking system?
12. A tractor-trailer's braking system supplies compressed air to which trailer brakes FIRST?
13. An S-cam is found in
14. When coupling a tractor to a trailer, how many air lines do you have to connect?
15. If there is a loss of air to the service brakes in a trailer with a spring brake priority system, how can you brake the trailer to a stop?
16. In a trailer with a spring brake priority system, compressed air is supplied to which brakes FIRST?
17. How many air lines must be connected to a DD3 safety actuator brake chamber?
18. The tractor protection valve closes to stop the flow of compressed air to
19. To uncouple your tractor from the trailer, how should you set the trailer air supply valve?
20. Which of the following is not a component of a wedge brake?
21. How often should you check brake chamber pushrod travel?
22. Which of the following is a part of a disc brake?
23. In an air braking system, which of the following is not commonly part of a disc brake?
24. Which of the following are helpful in reducing heat in the air brake system?
25. Which of the following can affect pushrod stroke?
26. If you find a major defect in the air brake system, you should
27. How can you determine applied pushrod stroke?
28. Which is least likely to cause brake drums to overheat?
29. When must full braking capability be available?
30. In Canada, antilock braking systems (ABS) have been mandatory on all trucks and buses over 4,560 kg that have been manufactured since
31. Which of the following is the best way to inspect an air compressor?
32. When can you adjust automatic slack adjusters?
33. If the outer layer of an air line is damaged, but the inner tube is still OK, what should you do?
34. To make sure the air tanks are securely attached to your vehicle, you should
35. Before inspecting your air brakes, you should
36. Your vehicle passes the tug test of the parking brakes if
37. If the brake chambers on opposite sides of an axle are of different sizes, the result may be
38. To check the brake chambers for leaks, you should
39. in a drum brake, the brake lining is fastened to
40. Compared with the service tanks, how much moisture should the supply tank discharge?
41. What is the appropriate action to take when brakes overheat due to overuse or improper adjustment?
42. Which of the following is incorrect about what could happen when the brake builds up too much heat?
43. What is the working mechanism of an air compressor?
44. What does MELT stand for when you must show you have completed an approved MELT course?
45. How far ahead can you book your driving test appointment?
46. Why are air brake systems predominantly used on large commercial vehicles?
47. After meeting what criteria can a licence holder be authorized to operate vehicles equipped with air brakes as a learner?
48. Who should supervise a learner handling air brakes?
49. What is the main function of the air compressor in a vehicle's brake system?
50. Which component allows the air to move through the system as quickly as possible?