In the event of a trailer breakaway, what safety measure does the tractor implement?

In the event of a trailer breakaway, the tractor implements a crucial safety measure by closing the protection valve. This action is essential because it prevents air from escaping the braking system, which ensures that the trailer's brakes can be engaged effectively. When the protection valve closes, it helps maintain the compressed air needed for the trailer’s braking system to function, allowing the trailer to stop safely instead of becoming detached and causing potential accidents.

Understanding this mechanism is vital for drivers of combination vehicles, as it highlights the importance of braking system integrity and the quick response needed in emergency situations. Other options, while they may appear relevant, do not specifically address the critical function of the protection valve in maintaining braking control after a breakaway.