Question What does the tractor protection valve do? Answers Protects the tractor from being stolen Protects the tractor from exceeding a set speed Keeps air in the braking system, should the trailer break away or develop a leak Ensures oil adequately lubricates the engine Explanation The tractor protection valve keeps air in the tractor or truck braking system, should the trailer break away or develop a bad leak. Take a FREE Practice Test Now This questions appears in the following tests: Illinois Double , Oregon Combination ,