What is the purpose of the relay valve in an air brake system?

The purpose of the relay valve in an air brake system is to enhance the responsiveness of the brakes. This component is crucial because it serves as an intermediary between the brake pedal and the brake chambers. When the driver applies the brakes, the relay valve quickly responds to the air pressure from the brake pedal and sends that air pressure to the brake chambers, allowing the brakes to engage more rapidly.

This quick response is essential for effective braking performance, especially in larger vehicles where the air pressure may need a moment to travel through long lines. By reducing the time it takes for air pressure to reach the brakes, the relay valve ensures that the braking system works efficiently, allowing for smoother and faster stops, which is vital for safety on the road.