What component in an air brake system prevents air from flowing back?

The component that prevents air from flowing back in an air brake system is a one-way check valve. This valve is designed to allow air to flow in one direction only, which is critical for maintaining the necessary air pressure in the braking system. When the brake pedal is pressed, air flows from the compressor into the brake chambers to activate the brakes. However, once the pressure is released, the check valve ensures that this air cannot flow back into the compressor system, thereby maintaining the pressure needed for effective braking.

The one-way check valve plays a vital role in the overall functioning of the air brake system by preventing potential issues such as pressure loss, which could lead to brake failure. This function is essential for keeping the braking system responsive and effective when needed. Other components, like the compressor, are responsible for generating air pressure, while the brake drum and pressure gauge serve different functions related to braking and monitoring air pressure, respectively.