Air Brake Coach
System failuresQuestion 41 of 116

How do you know that the supply circuit has failed?

  1. The ABS light flashes
  2. The yellow button pops out at once
  3. The gauges do not rise when pressure is below cut-in
  4. The trailer swings
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Correct answer: The gauges do not rise when pressure is below cut-in

With a supply failure, the gauges do not refill when pressure falls below the governor cut-in level.

Source: Air Brake Manual: A Guide for Instructors (Government of Alberta, Alberta Transportation, March/April 2012), Module 7: System failures, page 69

Practice system failures

Questions last reviewed: 18 October 2026