Air Brake Coach
System failuresQuestion 47 of 116

When you stop with a steady service application, when do you release it?

  1. At about 20 PSI
  2. At about 70 PSI
  3. At about 120 PSI
  4. At about 45 PSI
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Correct answer: At about 70 PSI

Release the service application near 70 PSI (483 kPa). The air pressure then rebuilds.

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