What is the primary function of the protection reservoir in a train system?

The primary function of the protection reservoir in a train system is to supply air to the braking system. In a train's pneumatic braking system, it’s critical to maintain adequate air pressure for the brakes to function effectively. The protection reservoir acts as a safeguard to ensure that in the event of an air pressure drop, there is still a reserve of air that can be used to apply the brakes, helping to prevent potential brake failure. This function is essential for maintaining safety and reliability in train operations.

While other components of the train system deal with energy efficiency, traction, and various forms of pressure regulation, the protection reservoir specifically addresses the need for consistent air supply necessary to operate the brake system safely.