What is the function of the automatic brake valve in the air brake system?

The automatic brake valve plays a critical role in the air brake system by controlling the application and release of the brakes. When the engineer operates the brake system, the automatic brake valve regulates the flow of compressed air to the brake cylinders, which engage the brakes. This valve allows for precise modulation of braking pressure, making it possible to apply brakes gradually or release them smoothly without sudden changes in braking force.

By adjusting air pressure as required, the automatic brake valve ensures that the train can stop effectively and safely, responding to varying conditions on the track. This function is essential for maintaining safe operation, particularly in longer trains that may require coordinated braking across multiple cars.