What does a relay valve in air brake systems do?

The function of a relay valve in air brake systems is primarily to increase the speed of air delivery to the brake chambers. This component plays a critical role in enhancing the responsiveness of the air brake system. When the driver engages the brakes, the relay valve quickly responds to the change in pressure and directs air to the brake chambers more effectively. By doing this, it reduces lag time between when the driver applies the brakes and when the brakes engage, leading to a more efficient and effective braking response.

The design of the relay valve allows it to work under different pressures, ensuring that the brake system operates smoothly even during varying conditions. This mechanism is essential for maintaining safety and control of the vehicle, particularly in larger trucks and buses where a quick response is crucial.

The other options refer to functions not directly associated with the relay valve. While weight reduction and backup functions are important aspects of the overall brake system, they do not accurately describe the specific role of the relay valve in providing rapid air delivery to enhance braking performance.