MPI Air Brake Test Practice

All 50 questions in this test

Every question and its answer choices. The correct answers and explanations appear when you take the test above.

1. What brake drum temperature does MPI call the danger level?

   1. About 120 °C
   2. About 590 °C
   3. About 220 °C
   4. About 300 °C

2. Which brake lining condition is a defect?

   1. Lining thicker than the minimum
   2. Lining soaked with grease or oil
   3. Lining touching the drum when applied
   4. Lining clear of the drum when released

3. How often does the law require brake adjustment to be checked on air brake vehicles?

   1. Only at the annual inspection
   2. At least once each day
   3. Once a week
   4. Once a month

4. The trailer service brakes fail while driving. How can you apply the trailer brakes?

   1. Pump the brake pedal rapidly
   2. Close the trailer supply valve
   3. Pull the round blue tractor parking knob
   4. Use the trailer hand valve harder

5. Inside a service brake chamber, what returns the pushrod when air is released?

   1. A return spring
   2. Air from the secondary tank
   3. The slack adjuster
   4. The parking brake spring

6. Do you need an air brake endorsement in Manitoba to drive a vehicle with air-over-hydraulic brakes?

   1. No, only full air brake systems need it
   2. Only for buses with air-over-hydraulic brakes
   3. No, a Class 3 licence covers it
   4. Yes; there is no separate air-over-hydraulic test

7. Why must brake chambers on each end of a steering axle be the same size?

   1. So the spring brakes release sooner
   2. So both chambers can share one air line to save hose
   3. So braking is balanced and steering unaffected
   4. So the slack adjusters wear faster

8. Your ABS warning light shows a malfunction. What braking do you still have?

   1. Regular brake function
   2. Only the trailer hand valve
   3. Only the spring brakes
   4. No brakes until repaired

9. You apply the pedal and the trailer hand valve at the same time. What pressure does the trailer get?

   1. The lower of the two pressures
   2. The higher of the two pressures
   3. Only the pedal pressure
   4. The two pressures added together

10. What happens to brake force once pushrod stroke exceeds the chamber's limit?

    1. It increases as the stroke gets longer
    2. It shifts to the spring brakes
    3. It stays the same at any stroke
    4. It drops sharply and may stop entirely

11. What are the lowest cut-in and highest cut-out pressures allowed in an air brake system?

    1. Cut-in no lower than 80 psi, cut-out no higher than 120 psi
    2. Cut-in no lower than 100 psi, cut-out no higher than 145 psi
    3. Cut-in no lower than 60 psi, cut-out no higher than 100 psi
    4. Cut-in no lower than 120 psi, cut-out no higher than 150 psi

12. When draining air tanks, which discharge should be reported?

    1. Clean air after the moisture drains
    2. Any oil, or a lot of moisture from non-supply tanks
    3. A short hiss when the valve opens
    4. A small amount of moisture from the supply tank only

13. Which foundation brake has no exposed linkage and is self-adjusting?

    1. The S-cam brake
    2. A disc brake with a slack adjuster
    3. A drum brake with manual slacks
    4. The wedge brake

14. What colours are gladhands usually coded?

    1. Black for both lines
    2. Yellow for supply, green for service
    3. Blue for supply, red for service
    4. Red for supply, blue for service

15. How are spring brakes applied and released?

    1. Applied by air pressure, released by a strong spring
    2. Applied by the foot pedal only
    3. Applied by hydraulic fluid, released by air
    4. Applied as air leaves, released as air builds

16. A farmer drives a farm-registered Class 3 truck with air brakes. Is an air brake endorsement needed?

    1. Only if the truck has three axles
    2. Yes, every vehicle with any air brakes at all needs one
    3. No, farm-registered Class 3 or 5 vehicles are exempt
    4. Only when hauling grain to an elevator

17. In the governor test, which cut-out reading is a defect?

    1. Cut-out at 140 psi
    2. Cut-out at 130 psi
    3. Cut-in at 105 psi
    4. Cut-out below 120 psi

18. A vehicle does not comply with the air brake rules of The Highway Traffic Act. Who must keep it off the road?

    1. Only the vehicle owner
    2. Only Manitoba Public Insurance
    3. The driver, operator and owner
    4. Only the mechanic who last serviced it

19. At what supply-line pressure does the trailer supply valve close automatically?

    1. Between 20 and 45 psi
    2. Between 90 and 100 psi
    3. At exactly 120 psi
    4. Between 60 and 70 psi

20. You notice a spring brake chamber with a caging bolt sticking out. What does it mean?

    1. That brake is disabled; have it repaired now
    2. The spring brakes are fully applied
    3. The chamber is a long-stroke type
    4. The brake has been prepared for a road test

21. Some school buses have air parking brakes and hydraulic service brakes. Is an air brake endorsement needed?

    1. No, air parking brakes alone do not require it
    2. Yes, any air component requires it
    3. Yes, plus an S endorsement
    4. Only for buses with more than 36 seats

22. How can you recognize a long-stroke brake chamber?

    1. A larger yellow knob in the cab
    2. Square ports, a trapezoid tag and markings
    3. Round air ports and no stroke tag on the clamp
    4. A blue clamp ring

23. What is the most common type of foundation brake on commercial vehicles with air brakes?

    1. The wedge brake
    2. The S-cam drum brake
    3. The disc brake
    4. The band brake

24. What does the trailer supply (emergency) line do?

    1. Carries air to fill the trailer's tanks
    2. Carries electrical power to the trailer lights
    3. Carries air only when the pedal is pressed
    4. Returns used air from the trailer

25. In a dual-circuit system, one circuit fails. What still works?

    1. Only the spring parking brakes
    2. Only the trailer hand valve
    3. The brakes on the other circuit's wheels
    4. Nothing; all the service brakes fail at once

26. Why does a single malfunctioning brake put the others at risk?

    1. It shuts off air to every other brake
    2. The other brakes work harder and can overheat
    3. It raises the governor cut-out pressure
    4. It makes the ABS release all wheels

27. What is the adjustment limit for a standard type 30 clamp-type chamber?

    1. 1 3/8 in. (35 mm)
    2. 2 in. (51 mm)
    3. 2 1/2 in. (64 mm)
    4. 3 in. (76 mm)

28. Why might poorly adjusted brakes go unnoticed?

    1. The low air warning hides it
    2. They make the pedal feel softer at all times
    3. The loss shows mainly under heavy demand
    4. They only affect the trailer in reverse

29. What does the tractor protection valve do when the trailer supply valve closes?

    1. It applies the tractor's front brakes
    2. It opens wide and dumps all of the tractor's air
    3. It switches the compressor off
    4. It closes, keeping air in the towing vehicle

30. What does a round blue knob in some tractors control?

    1. Releasing tractor spring brakes only, trailer's stay on
    2. Applying the trailer service brakes
    3. Draining all tanks at once
    4. Supplying air to fill the trailer tanks before coupling

31. After meeting the written standard, who may supervise you as an air brake learner?

    1. A driver who has just passed the practical test
    2. Any driver who has held a Class 1 licence for one full year
    3. Someone with the endorsement for at least two years
    4. Any adult passenger in the cab

32. During the tractor protection test, the trailer supply valve must close before pressure drops below what?

    1. 60 psi
    2. 90 psi
    3. 45 psi
    4. 20 psi

33. What does ABS do in an emergency stop?

    1. Increases the air pressure to all wheels
    2. Applies the spring brakes automatically
    3. Prevents wheel lock so you keep steering control
    4. Shortens stopping distance on any road

34. How do you supply air to the trailer with a push/pull trailer supply valve?

    1. Pull out the red eight-sided knob
    2. Push in the red eight-sided knob
    3. Pull out the round blue knob
    4. Push in the yellow four-sided knob

35. Why should you never service or repair a spring brake chamber yourself?

    1. It voids the vehicle's registration and insurance
    2. It changes the governor settings
    3. The compressed spring can release violently
    4. It lets moisture into the tanks

36. While driving, air pressure drops below the normal cut-in setting. What should you do?

    1. Stop safely as soon as possible
    2. Speed up so the compressor works harder
    3. Keep driving; it will recover
    4. Pump the brakes to raise the pressure

37. In the build-up test, how long may pressure take to rise from 85 to 100 psi at 600–900 rpm?

    1. Five minutes or less
    2. Two minutes or less
    3. Ten minutes or less
    4. 30 seconds or less

38. If you double your speed, what happens to your stopping distance?

    1. It doubles
    2. It increases about four times
    3. It increases eight times
    4. It stays the same with good brakes

39. What can happen if the trailer air lines are cross-connected?

    1. The trailer gets double braking power
    2. Only the trailer lights stop working
    3. Spring brakes may not release; tractor may lose air
    4. The brakes still work normally but make more noise

40. What does the spring brake control valve knob usually look like?

    1. Red and eight-sided
    2. Green and square
    3. Yellow and four-sided
    4. Blue and round

41. What is one problem caused by moisture and oil collecting in air tanks?

    1. Sludge that damages seals and makes valves stick
    2. Better lubrication of the brake chambers
    3. Quieter operation of the compressor
    4. Faster air build-up and higher pressure

42. When should you inspect the air compressor?

    1. With the engine at high idle
    2. While the compressor is pumping
    3. With the trailer supply valve open
    4. With the engine stopped

43. How long can the delay in applying and releasing air brakes be?

    1. Up to about half a second
    2. Up to two full seconds
    3. Up to about five seconds
    4. Less than one hundredth of a second

44. Trailer spring brakes must apply automatically when supply-line pressure drops below what level?

    1. 90 psi
    2. 60 psi
    3. 110 psi
    4. 20 psi

45. What happens when you press the brake pedal harder?

    1. Air flows back into the supply tank
    2. The governor cuts out sooner to save air
    3. The valve opens more, sending more pressure
    4. The spring brakes start to apply

46. Which tank should you drain first?

    1. The secondary (dry) tank
    2. The trailer tank
    3. The supply (wet) tank
    4. The primary (dry) tank

47. What is a slack adjuster's effective length?

    1. Camshaft centre to clevis pin distance
    2. The distance between the two axles
    3. The diameter of the brake chamber
    4. The length of the pushrod when the brake is released

48. In an S-cam brake, what turns the camshaft?

    1. A hydraulic cylinder at the wheel
    2. The return spring pulling the shoes
    3. Pushrod stroke acting on the slack adjuster
    4. The brake drum spinning against it

49. When must the trailer hand valve never be used?

    1. During coupling
    2. For parking or emergency stops
    3. When testing trailer brakes
    4. To check the service line

50. In Manitoba, who may re-adjust automatic slack adjusters?

    1. Any driver with an S endorsement
    2. The vehicle owner
    3. Only certified technicians
    4. Any driver with an A endorsement