Question What is a tractor protection valve? Answers A valve to keep air in the brake system should there be a bad leak A valve that prevents the truck from being stolen A valve that prevents the driver from going too fast A valve that prevents the trailer from accidentally being released Explanation In a combination vehicle with air brakes, the tractor protection valve keeps air in the tractor or truck brake system in the event of the trailer breaking away or developing a leak. Take a FREE Practice Test Now This questions appears in the following tests: Colorado Combination , Florida Combination , Indiana Combination , Nebraska Combination ,