Canada Exam Prep
Ontario Class A (AZ) overview

Ontario Class A (AZ): Coupling and uncoupling

Step-by-step uncoupling and coupling of a tractor and semi-trailer: securing both units, landing gear, fifth-wheel height, the tug test, visual checks of jaws and plate, air lines and the road-test scoring.

  • 23 questions
  • Topic drill
0/23
Coupling and uncoupling · Question 1Score 0/0

Before pulling forward against the pin, how do you keep the trailer from rolling?

Study reference: MTO Truck Handbook (online edition, 2026), Ch. 1 Getting your licence — Uncoupling and coupling of combinations (class A only)

All 23 questions in this test

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

  1. Before pulling forward against the pin, how do you keep the trailer from rolling?

    1. Raise the landing gear
    2. Lower the tractor's air suspension
    3. Set the trailer brakes
    4. Open the trailer supply valve fully

  2. When should you raise the landing gear after coupling?

    1. After checking the hook-up
    2. Only once you reach the delivery point
    3. After driving the first kilometre
    4. Before backing under the trailer

  3. How far should you lower the landing gear when uncoupling?

    1. Until it lifts the trailer two inches
    2. Just above or just touching the ground
    3. Halfway, then let the tractor lower it
    4. All the way until the pads stop

  4. What is the industry colour for the trailer service air line?

    1. Blue
    2. Yellow
    3. Red
    4. Green

  5. How fast should you reverse the tractor when coupling?

    1. At about 15 km/h
    2. In a quick burst
    3. At a walking pace
    4. As fast as idle allows

  6. What should you do just before reversing under a trailer?

    1. Release the trailer's spring brakes
    2. Raise the landing gear fully
    3. Connect the air lines first
    4. Check the path, flashers on, sound horn

  7. Before lowering the landing gear, what should you check about the ground?

    1. That it is wet so the pads slide
    2. That it is level and firm
    3. That it is gravel, not pavement
    4. That it is sloped toward a drain

  8. What is the most pull-ups you may use to complete the coupling on the road test?

    1. Unlimited
    2. 10
    3. 2
    4. 5

  9. What is the first step when uncoupling a tractor and semi-trailer?

    1. Lower the landing gear
    2. Unlock the fifth wheel
    3. Disconnect the air lines
    4. Secure both units

  10. How are the safety chains or cables connected on a non-fifth-wheel combination?

    1. Parallel
    2. Crossed
    3. Left hanging loose
    4. Knotted together

  11. You see a gap between the trailer upper plate and the fifth wheel. What does it mean?

    1. The trailer is properly seated
    2. The coupling is not secure
    3. The landing gear is still down
    4. The air suspension is inflated

  12. Why keep the tractor frame under the trailer before pulling fully clear?

    1. To keep the trailer lights on
    2. To save the tractor's fuel
    3. In case the trailer is unstable
    4. To keep the air lines connected

  13. How high should the trailer be compared with the fifth wheel?

    1. Exactly level with the frame rails
    2. Low enough to be lifted slightly
    3. As low as the landing gear allows
    4. High enough to clear it by 10 cm

  14. On the Class A road test, how many errors are allowed in uncoupling and coupling combined?

    1. Ten
    2. Five
    3. Two
    4. None

  15. After unlocking the fifth wheel, how far do you first pull the tractor forward?

    1. Just far enough to release the fifth wheel
    2. Fully clear of the trailer in one move
    3. About 10 m to test the trailer brakes
    4. Until the landing gear lifts the trailer

  16. What does "hitting the pin" mean?

    1. Pulling the fifth-wheel release pin out
    2. Backing sharply to set the kingpin in the jaws
    3. Tapping the kingpin with a heavy hammer
    4. Inserting the safety pin in the landing gear

  17. Before uncoupling or coupling, what should you do with the cab windows and audio?

    1. Windows up, radio on low
    2. Windows down, audio off
    3. No change is needed
    4. Windows up, CB radio on

  18. In which gear should the landing-gear crank handle be stowed?

    1. Neutral
    2. Reverse
    3. High gear
    4. Low gear

  19. After charging the trailer with air, how do you check the connections for leaks?

    1. Drive and watch the gauges
    2. Engine off, listen at each line
    3. Drain the trailer tanks
    4. Spray soap on the fifth wheel

  20. From where do you confirm that the fifth-wheel jaws have closed around the kingpin?

    1. From the driver's seat using the mirrors
    2. From the trailer's open rear doors
    3. From a ladder on top of the trailer
    4. Under the trailer, behind the tractor

  21. What can happen if the trailer is too high when you back under it?

    1. The air lines will cross
    2. The tractor will hit the trailer nose
    3. The landing gear will collapse
    4. It may not couple correctly

  22. Where should you stop the fifth wheel on the first approach to the trailer?

    1. Firmly against the trailer kingpin
    2. Just ahead of or slightly under it
    3. Directly underneath the landing gear
    4. About two metres in front of the trailer

  23. What is the tug test?

    1. Pulling the release lever to test it
    2. Pulling forward to raise the landing gear
    3. Pulling the gladhands to test the seal
    4. Pulling against the trailer to test the lock

Coupling and uncoupling: key rules to remember

Our summary of what the official handbook says on this topic, in our own words. Read it before or after the practice questions above, then check the original chapter. Read the official chapter ↗

Before you start

  • Incorrect coupling or uncoupling can be very dangerous; learn the details of the specific truck and trailer you will drive.
  • Roll down the windows, turn off audio, sound the horn before backing (electric horn on the road test) and confirm the spot is suitable and safe.

Uncoupling steps

  • Secure both units: apply tractor and trailer parking brakes, put the transmission in park or neutral and chock the trailer wheels.
  • Check that the ground is level and firm, then lower the landing gear until it is just above the ground or just touching it without lifting the trailer off the fifth wheel.
  • Stow the landing-gear handle in low gear.
  • Disconnect and stow the air and electrical lines and any safety chains or cables.
  • Unlock the fifth wheel (or coupling device).
  • Pull the tractor forward only far enough to release the fifth wheel, leaving the tractor frame still under the trailer; apply the parking brakes and select neutral.
  • Get out and confirm the trailer is stable before pulling the tractor fully clear.
  • On a non-fifth-wheel combination, raise the trailer until its coupling clears the truck's coupling, confirm it is stable, then release the truck parking brake and pull ahead slowly.

Coupling steps

  • Inspect the fifth wheel (or coupling device), air and electrical lines and connections before backing.
  • Line up the tractor and trailer and check trailer height and alignment; before reversing, check the path, turn on the four-way flashers and sound the horn (not needed if an automatic backing alarm is fitted).
  • Reverse slowly at a walking pace until the fifth wheel is just ahead of, touching or slightly under the trailer, but not against the kingpin.
  • For a non-fifth-wheel unit, stop about one foot ahead of the trailer connection point; touching the trailer is acceptable but moving the wheel chocks is not.
  • The trailer should be low enough that the tractor lifts it slightly when backed under it; too low and the tractor can hit the trailer nose, too high and it may not couple correctly.
  • Back under to engage the fifth wheel, then do a tug test by pulling against the trailer to prove it is locked.
  • Safety chains or cables are connected crossed.

Checking the hook-up

  • "Hitting the pin" is backing in a short, sharp motion to drive the kingpin into the jaws.
  • Then set the trailer brakes (hand control or trailer parking brake) and try to pull forward against the pin in the lowest gear.
  • Get out and look: there must be no space between the trailer upper plate and the fifth wheel; any gap means the coupling is not secure.
  • The release lever must be in the locked position and any secondary lock engaged.
  • From behind the tractor and under the trailer, confirm the jaws are fully closed around the kingpin.

After hook-up

  • Connect the air lines (blue = service, red = supply or emergency) and the electrical line, plus any breakaway device.
  • Raise the landing gear fully before moving and stow the handle; with a two-speed crank, leave it in low range.
  • Charge the trailer with the trailer supply valve, then shut the engine off and listen for leaks at the supply connection, then apply the service brakes and listen at the service connection.
  • Drive forward slowly and test the brakes as soon as possible.

Coupling scoring

  • On the road test you uncouple first, then couple, at a location chosen as safe.
  • You are allowed up to two errors in total for uncoupling and coupling, and must complete the coupling in no more than 5 pull-ups.

Study the Coupling and uncoupling rules as flashcards →

Other topics

Full practice tests