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Practice quizzes / Ontario Air Brake Z Test Practice Questions - Ontario Air Brake (Z Endorsement) Knowledge Test Exam / Question 160745
Practice question

What happens when trailer supply-line pressure drops below about 60 psi?

  1. Trailer spring brakes must apply automatically
  2. Trailer service brakes are disabled forever
  3. Gladhands change colour
  4. The air dryer measures pushrod stroke

Answer: A — Trailer spring brakes must apply automatically

The correct answer is shown above. Try the full quiz for additional practice.

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