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Coupling and Uncoupling Trailers Flashcards

7 cards from real DTT HGV practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Coupling and Uncoupling Trailers flashcards as text

  1. Before reversing a tractor unit under a semi-trailer for coupling, the fifth wheel should be:

    Answer: Clean, greased and in the unlocked (open) position

    The fifth wheel must be greased and in the open/unlocked position so the kingpin can enter and the jaws can close around it during coupling.

  2. The kingpin on a semi-trailer connects with which part of the tractor unit?

    Answer: The fifth wheel coupling plate

    The kingpin is the steel pin on the underside of the trailer that locks into the jaws of the fifth wheel coupling plate on the tractor unit.

  3. After coupling a trailer, how should you test that the coupling is secure?

    Answer: Attempt to move forward with the trailer parking brake applied

    Moving forward against the applied trailer parking brake confirms the fifth wheel jaws are properly locked around the kingpin without risking movement.

  4. When uncoupling a semi-trailer, which sequence of steps is correct?

    Answer: Apply trailer brake, lower landing gear, disconnect airlines, release fifth wheel, drive away

    The trailer brakes must be applied and landing gear lowered to support the trailer's weight before the airlines are disconnected and the fifth wheel is released.

  5. After connecting the airlines to a trailer, what should you do before departure?

    Answer: Allow air pressure to build and check for air leaks

    Air pressure must reach the correct level and the system must be checked for leaks to ensure the trailer's braking system will function safely.

  6. The red (emergency) airline on a truck-trailer combination controls:

    Answer: The spring (parking/emergency) brakes on the trailer

    The red airline supplies air to hold the trailer's spring brakes off; if this line breaks or is disconnected, the spring brakes automatically apply.

  7. The landing legs of a semi-trailer must be fully raised:

    Answer: Before the vehicle combination moves off

    The landing legs must be fully raised and secured before any movement, as they could otherwise contact the road surface and cause a serious accident.

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