Practice question

Which choice is safest and most consistent with FLHSMV/FMCSA rules for tractor protection valve check?

It should stay in at zero psi
It should pop out only above 100 psi
It is checked by lowering landing gear
The trailer air supply control should pop out in the manufacturer-specified low-pressure range, usually 20 to 45 psi

Answer: D — The trailer air supply control should pop out in the manufacturer-specified low-pressure range, usually 20 to 45 psi

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