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Air Brake (Q Endorsement) Practice · Question

Scenario 91: On a tractor protection valve, the purpose is to:

If trailer air pressure drops sharply, the tractor protection valve closes to preserve tractor air supply for tractor brakes and steering. The correct answer is

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Question: Scenario 91: On a tractor protection valve, the purpose is to:

Answer options: ✅ Protect the tractor's air system if a trailer breakaway or major line leak occurs

  • Protect the engine
  • Protect the cab
  • Boost trailer braking

Correct answer: Protect the tractor's air system if a trailer breakaway or major line leak occurs

Explanation: If trailer air pressure drops sharply, the tractor protection valve closes to preserve tractor air supply for tractor brakes and steering. The correct answer is "Protect the tractor's air system if a trailer breakaway or major line leak occurs". This capacity-fill scenario 91 reinforces the same competency for the airbrake bank and follows the certified explanation standard.

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