What occurs if the air pressure in the tractor protection valve is too low?

When the air pressure in the tractor protection valve is too low, the valve will pop out. This safety feature helps to prevent potential accidents or system failures. The tractor protection valve is designed to automatically close if the air pressure drops below a certain threshold, which keeps air pressure in the brake system from depleting completely. When this happens, the valve's mechanism will trigger and pop out, effectively isolating the trailer brakes from the tractor, ensuring that the tractor can still stop safely. This design is crucial for maintaining control of the vehicle in case of an air pressure failure.

Low air pressure indicates a problem with the system, and the popping out of the valve serves as an alert to the driver that action needs to be taken to address the issue before proceeding.