What are spring brakes designed to do?

Spring brakes are a crucial safety feature in air brake systems, specifically designed to engage automatically in the event of a loss of air pressure. When air pressure drops in the brake system, which can happen due to leaks or other failures, the spring brakes are activated by powerful mechanical springs. These springs exert force on the brake assemblies, ensuring that the brakes are applied and the vehicle comes to a stop.

This design is essential for the safe operation of large vehicles, as it prevents them from rolling uncontrolled if there is a failure in the air pressure system. By using springs to mechanically apply the brakes, the system provides a reliable means of stopping the vehicle when needed, protecting both the driver and others on the road.

In contrast, other options suggest functionalities that do not align with the primary role of spring brakes. For instance, spring brakes are not intended for engagement during high-speed driving or to enhance braking power in emergencies. Similarly, increasing tire longevity is not a function related to the operation of spring brakes. The emphasis is clearly on safety and reliability in the case of a malfunction within the air brake system.