What activates the automatic drain valve?

The automatic drain valve is primarily activated by the governor in the system. The governor monitors the pressure levels in the pneumatic system, ensuring they remain within specified limits. When the pressure exceeds a set threshold, the governor triggers the automatic drain valve to open, allowing excess moisture or condensation to be expelled from the system. This function is essential for maintaining optimal air quality and preventing issues such as corrosion and reduced efficiency within the train's pneumatic systems.

While other components like a pressure sensor or timer may be involved in monitoring or controlling different aspects of the system, the governor plays the direct role in managing the operation of the automatic drain valve based on pressure conditions. Thus, the activation mechanism effectively connects to the governor's purpose of ensuring the system operates at a safe and efficient pressure level.