Air Brake Coach
TrailersQuestion 37 of 116

What must you do to a trailer when you uncouple it?

  1. Leave the red button in
  2. Chock it so it cannot move
  3. Drain only the supply tank
  4. Leave the glad hands open
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Correct answer: Chock it so it cannot move

An uncoupled trailer must be chocked to stop it from moving.

Source: Air Brake Manual: A Guide for Instructors (Government of Alberta, Alberta Transportation, March/April 2012), Module 6: Tractor and trailer circuits, page 68

Practice trailers

Questions last reviewed: 18 October 2026