Air Brake Coach
System failuresQuestion 45 of 116

What happens to the service circuits when the park circuit fails?

  1. Only the trailer circuit loses air
  2. Nothing changes
  3. The park brakes release
  4. Both service circuits lose air pressure
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Correct answer: Both service circuits lose air pressure

The park circuit takes air from both service circuits. A park circuit failure drains both.

Source: Air Brake Manual: A Guide for Instructors (Government of Alberta, Alberta Transportation, March/April 2012), Module 7: System failures, page 71

Practice system failures

Questions last reviewed: 18 October 2026