In an air brake system, what component is used to ensure a safe stop without air pressure?

In an air brake system, an emergency brake system is designed to automatically engage in the event of a loss of air pressure, allowing the vehicle to come to a safe stop. This system is essential because air brakes rely on compressed air to operate; if there is a failure in the air pressure, the emergency brake system activates, providing a means of stopping the vehicle without relying on the normal brake operation.

The emergency brake could utilize spring brakes, which are held in the released position by air pressure. When air pressure drops below a certain threshold, the brakes are engaged, using the energy stored in the spring to stop the vehicle safely. This system is critical for maintaining safety during unexpected air pressure loss.

Other components mentioned, while part of the brake system, do not serve the specific function of automatically ensuring a safe stop in the absence of air pressure. Therefore, the emergency brake system is vital for the safety and reliability of vehicles equipped with air brakes.