How does the 'fail-safe' feature in air brakes function?

The 'fail-safe' feature in air brakes is designed to automatically apply the brakes in the event of a system failure, ensuring the safety of the train and its passengers. This mechanism operates on the principle that if there is a loss of air pressure or failure in the air brake system, the brakes will spring into action, applying themselves to stop the train. This function is critical for preventing accidents and maintaining control over the train, allowing for rapid response in emergency situations.

This feature is essential because it addresses potential issues that could arise from system malfunctions, such as air leaks or equipment failure. By ensuring that the brakes engage automatically under these circumstances, the fail-safe system enhances reliability and safety, making it a crucial component of modern air brake systems used in trains.