B.C. Class 1 Knowledge Practice Test 2026: Practice test 4

1. Question 1 of 25

   In this air brake diagram, what is the job of the air compressor?

   • ATo remove water from the tanks
   • BTo pump air into the storage tanks
   • CTo measure push rod stroke
   • DTo apply the parking brake
   Show answer

   Answer: B. To pump air into the storage tanks

   The engine-driven compressor pumps air into the tanks.

2. Question 2 of 25

   Since April 1, 2000, which trailers must have anti-lock brakes in Canada?

   • AOnly trailers under 1,000 kg
   • BNo trailers; only the tractor needs it
   • COnly boat and recreational trailers
   • DCommercial trailers with air brakes
   Show answer

   Answer: D. Commercial trailers with air brakes

   ABS is mandatory on commercial trailers with air brakes, and on trucks and buses over 4,560 kg built since April 1, 2000.

3. Question 3 of 25

   Why do you check for air leaks with the brakes applied?

   • ALeaks drain air quickly just when you need the brakes
   • BTo test that the horn works on air
   • CTo warm up the engine before driving
   • DTo check the tire pressure on each wheel
   Show answer

   Answer: A. Leaks drain air quickly just when you need the brakes

   Leaks reduce the air available for braking, and they get worse when the system is under pressure.

4. Question 4 of 25

   Why are spring brakes used for parking?

   • AThey are the only brakes fitted to the trailer
   • BThey hold mechanically, without needing air in the system
   • CThey are stronger only while the engine runs
   • DThey use less fuel than the service brakes
   Show answer

   Answer: B. They hold mechanically, without needing air in the system

   Service brakes rely on air pressure, which can leak away. Spring brakes hold with spring force.

5. Question 5 of 25

   Before you drive, the air gauge shows low pressure. What should you do?

   • ADrive off and let it build while moving
   • BDrain the tanks and start again
   • CLet the pressure build to normal before moving
   • DRelease the spring brakes by hand
   Show answer

   Answer: C. Let the pressure build to normal before moving

   Do not move until the air pressure has built up and the low air warning has gone off.

6. Question 6 of 25

   Why does air brake lag matter for following distance?

   • AIt adds distance before the brakes work, so you need a bigger gap
   • BIt only matters when the vehicle is parked
   • CIt lets you follow more closely than a car
   • DIt makes the brakes work instantly, so gaps can be small
   Show answer

   Answer: A. It adds distance before the brakes work, so you need a bigger gap

   Lag time is added to perception and reaction time, so the truck travels further before braking starts.

7. Question 7 of 25

   What does too much push rod stroke mean?

   • AThe brake is working perfectly
   • BThe governor is set too low
   • CThe brake is out of adjustment
   • DThe tank is too full
   Show answer

   Answer: C. The brake is out of adjustment

   Excess push rod travel means the brake is out of adjustment and will not give full braking force.

8. Question 8 of 25

   What does the parking brake control knob usually look like?

   • AA green toggle switch
   • BA blue, square lever
   • CA yellow, diamond-shaped push-pull knob
   • DA red, round push button
   Show answer

   Answer: C. A yellow, diamond-shaped push-pull knob

   The parking (spring) brake control is a yellow, diamond-shaped push-pull knob.

9. Question 9 of 25

   During an air brake check, what should happen when you reduce the air pressure by fanning the brakes?

   • AThe engine should stop when pressure falls
   • BThe spring brakes should apply before the warning comes on
   • CThe low air warning should come on before the spring brakes apply
   • DNothing should happen until the tanks are empty
   Show answer

   Answer: C. The low air warning should come on before the spring brakes apply

   The warning must activate before pressure falls low enough for the spring brakes to apply.

10. Question 10 of 25

    Why should you avoid fanning (pumping) air brakes?

    • AIt wastes air and lowers the pressure in the system
    • BIt drains fuel from the tank
    • CIt makes the brakes far too strong
    • DIt overheats the engine and compressor
    Show answer

    Answer: A. It wastes air and lowers the pressure in the system

    Each pump uses air. Fanning the brakes can drop pressure quickly.

11. Question 11 of 25

    A truck has 16 brakes and one is out of adjustment. What happens?

    • AThe truck stops faster than before
    • BThe air compressor stops pumping
    • CNothing; one brake out of 16 does not matter
    • DThe other brakes must do more of the work
    Show answer

    Answer: D. The other brakes must do more of the work

    Each brake is designed to do its share. If one is out of adjustment, the others work harder and may overheat.

12. Question 12 of 25

    Why must water be drained from air tanks?

    • AWater can freeze and block valves and lines
    • BWater makes the brakes stronger
    • CWater cools the engine
    • DWater is needed for the brakes to work
    Show answer

    Answer: A. Water can freeze and block valves and lines

    Water and oil collect in the tanks. In cold weather, water can freeze and stop the system working.

13. Question 13 of 25

    About how much time does air brake lag add before the brakes begin to apply?

    • AAbout four-tenths of a second
    • BAbout 4 seconds
    • CAbout 1 full minute
    • DNo time at all
    Show answer

    Answer: A. About four-tenths of a second

    Air brake lag time is about 4/10 of a second.

14. Question 14 of 25

    For how long is a passed air brake knowledge test result valid in B.C.?

    • AFor life
    • BFive years
    • COne year
    • DOne month
    Show answer

    Answer: C. One year

    The air brake knowledge test result is valid for one year.

15. Question 15 of 25

    What should you check on the compressor during the air brake inspection?

    • AThe colour and make of the compressor
    • BThat a belt-driven compressor's belt is in good shape and tight
    • CThe fuel level inside the compressor
    • DThe compressor's radio and wiring connection
    Show answer

    Answer: B. That a belt-driven compressor's belt is in good shape and tight

    A loose or worn belt can stop the compressor from building air.

16. Question 16 of 25

    Where do you apply to take the air brake knowledge test in B.C.?

    • AAt your trucking company
    • BAt a police station
    • CAt a driver licensing office
    • DAt a weigh scale
    Show answer

    Answer: C. At a driver licensing office

    Apply at a driver licensing office with your ID and pay the knowledge test fee.

17. Question 17 of 25

    How is brake adjustment checked on S-cam brakes?

    • ABy listening to the brakes while driving slowly
    • BBy checking the tire pressure on each axle
    • CBy measuring push rod stroke with the brakes fully applied
    • DBy feeling how hot each drum is after a trip
    Show answer

    Answer: C. By measuring push rod stroke with the brakes fully applied

    Measure how far the push rod moves on a full application. Too much stroke means the brake is out of adjustment.

18. Question 18 of 25

    Is a road test required for the air brake endorsement in B.C.?

    • AYes, in a tractor-trailer
    • BNo
    • CYes, but only at night
    • DYes, in a bus
    Show answer

    Answer: B. No

    The air brake endorsement needs a knowledge test and a pre-trip inspection test, but no road test.

19. Question 19 of 25

    When air enters a brake chamber, what moves?

    • AA diaphragm pushes the push rod out
    • BThe brake drum starts to spin faster
    • CThe governor cuts out the compressor
    • DThe tank drain valve opens
    Show answer

    Answer: A. A diaphragm pushes the push rod out

    Air pressure pushes the diaphragm, which pushes the rod that turns the slack adjuster.

20. Question 20 of 25

    How does a retarder help the air brakes?

    • AIt adds extra air to the tanks while you drive
    • BIt makes the service brakes apply faster
    • CIt adjusts the slack adjusters automatically
    • DIt slows you without the service brakes, so they stay cool
    Show answer

    Answer: D. It slows you without the service brakes, so they stay cool

    Retarders such as engine and exhaust brakes reduce the work, heat and wear on the service brakes.

21. Question 21 of 25

    What is the possible fine for brakes that are not correctly adjusted?

    • AUp to $20
    • BUp to $100
    • CUp to $2,000
    • DNo fine, only a warning
    Show answer

    Answer: C. Up to $2,000

    Brakes not adjusted or not performing properly can bring a fine of up to $2,000.

22. Question 22 of 25

    Which part senses tank pressure and controls the compressor?

    • AThe slack adjuster
    • BThe governor
    • CThe brake chamber
    • DThe brake drum
    Show answer

    Answer: B. The governor

    The governor tells the compressor when to stop (cut out) and start (cut in) pumping.

23. Question 23 of 25

    On a Class 1 road test in a vehicle with air brakes, which inspection is included?

    • AA full engine inspection
    • BA tire change on the trailer
    • CAn air brake pre-trip inspection
    • DA fuel economy check
    Show answer

    Answer: C. An air brake pre-trip inspection

    Road tests include an air brake pre-trip inspection when the vehicle has air brakes.

24. Question 24 of 25

    What connects the push rod to the brake camshaft?

    • AThe gladhand
    • BThe foot valve
    • CThe slack adjuster
    • DThe governor
    Show answer

    Answer: C. The slack adjuster

    The slack adjuster links the push rod to the camshaft and adds leverage.

25. Question 25 of 25

    What temperature should brake parts not go above?

    • AAbout 900 °C
    • BAbout 60 °C
    • CAbout 250 °C
    • DAbout 120 °C
    Show answer

    Answer: C. About 250 °C

    Brake parts reach about 120 °C in normal stops and should not exceed about 250 °C.

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