Air Brake Coach
System failuresQuestion 49 of 116

The trailer service brakes do not work and you must stop quickly. What do you do?

  1. Pull the trailer air supply valve (red button)
  2. Push in the yellow button
  3. Pump the foot valve
  4. Cage the park springs
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Correct answer: Pull the trailer air supply valve (red button)

Pulling the red button applies the trailer spring brakes and stops the vehicle quickly.

Source: Air Brake Manual: A Guide for Instructors (Government of Alberta, Alberta Transportation, March/April 2012), Module 7: System failures, page 72

Practice system failures

Questions last reviewed: 18 October 2026