You are testing the tractor protection valve. Which result shows that the valve is working properly?

Answer options

Why

For this test, charge the trailer brakes, shut off the engine, and pump the brake pedal to bring the air pressure down. If the valve works, the trailer air supply knob, also known as the tractor protection valve control, should pop out (or switch to "emergency"), usually when pressure drops to somewhere between 20 and 45 psi.

About this question

Topic: Combination vehicles   License: CDL

Part of these practice sets:

• Trailer Air Lines and Coupling

Where it applies: Asked in every state.

Practice the whole set

This question is part of Trailer Air Lines and Coupling (28 questions). Take the full set and check your score.

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