What reliability feature do spring parking brakes offer?

Spring parking brakes provide the reliability feature of operating without the need for air pressure, which is crucial for their function. This system relies on mechanical springs to engage the brake when it is required, such as when the vehicle is parked. This design means that even in situations where air pressure may fail or drop (such as in the event of an air system leak), the spring brakes will still engage effectively, ensuring that the vehicle remains stationary.

The absence of reliance on air pressure adds a layer of safety and reliability to spring parking brakes, making them a preferred choice for heavy trailers, especially in emergency scenarios or when parked on an incline. This operational independence enhances their effectiveness compared to other braking systems that might not function properly without sufficient air pressure.