Answer :
Final answer:
The tractor protection valve's main purpose is to protect the brake system from underpressure by automatically cutting off the air supply to the trailer if the air pressure drops too low.
Explanation:
The main purpose of a tractor protection valve is to protect the brake system from underpressure. If the air pressure falls below a certain level, the valve automatically cuts off the air supply to the trailer, preventing a loss of air in the tractor. This ensures that the tractor retains enough air pressure to stop safely, thereby protecting the brake system's integrity and preventing potential road accidents.
