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During the inspection pop-out test, the trailer supply knob does not pop as pressure falls through 30 psi. What does this indicate?
- A.The test passed with an alternative method
- B.Knobs are never supposed to pop in tests
- C.The tractor protection or trailer supply valve is not operating correctly and needs repair before hauling a trailer
- D.Only the trailer paint is at fault
Correct answer
C. The tractor protection or trailer supply valve is not operating correctly and needs repair before hauling a trailer
Why
Automatic pop-out is the proof that a real breakaway or major leak would protect the tractor and stop the trailer. A valve that fails in the test bay will fail the same way on the highway.
Manual topic: Air Brakes - Spring Brakes and Parking Brakes · From the Air Brakes practice bank (AB-123).