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Class 1 Commercial Driver Practice · Question

After a full-pressure release with the engine off, a tractor-trailer air system pressure drop should not exceed:

Maximum allowable leakage with brakes applied is 3 psi/min for a tractor-trailer combination (2 psi/min for single vehicle).

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Question: After a full-pressure release with the engine off, a tractor-trailer air system pressure drop should not exceed:

Answer options:

  • 1 psi/min
  • 2 psi/min ✅ 3 psi/min
  • 6 psi/min

Correct answer: 3 psi/min

Explanation: Maximum allowable leakage with brakes applied is 3 psi/min for a tractor-trailer combination (2 psi/min for single vehicle).

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