Tractor protection valves close automatically when air pressure falls to:

20-45 psi.. Section 6.2 (Air Brakes overlap): The tractor protection valve closes between 20 and 45 psi to save air for the truck brakes.

Tractor protection valves close automatically when air pressure falls to:

ANSWER BREAKDOWN
  • A. Correct. Section 6.2 (Air Brakes overlap): The tractor protection valve closes between 20 and 45 psi to save air for the truck brakes.
  • B. Incorrect. "60 psi." is not correct. Section 6.2 (Air Brakes overlap): The tractor protection valve closes between 20 and 45 psi to save air for the truck brakes.
  • C. Incorrect. "100 psi." is not correct. Section 6.2 (Air Brakes overlap): The tractor protection valve closes between 20 and 45 psi to save air for the truck brakes.
  • D. Incorrect. "80 psi." is not correct. Section 6.2 (Air Brakes overlap): The tractor protection valve closes between 20 and 45 psi to save air for the truck brakes.