New Jersey Air Brakes Practice Test

What is the primary function of spring brakes in a truck?

1. To enhance the overall braking performance

2. To act as backup brakes in case of air pressure loss

3. To reduce wear on the service brakes

4. To increase the vehicle's stopping distance

The correct answer is: To act as backup brakes in case of air pressure loss

The primary function of spring brakes in a truck is to serve as backup brakes in case of air pressure loss. Spring brakes are designed to engage automatically when the air pressure in the brake system drops below a certain threshold, which is critical for safety. This feature ensures that even in the event of a failure in the air brake system, the vehicle can still come to a stop, preventing uncontrolled movement and possible accidents. Spring brakes utilize a strong spring mechanism to apply force to the brake shoes when the air pressure that keeps the brakes released is lost. This redundancy in braking capability is essential for heavy vehicles that rely on air brakes for their standard braking operation. With this system in place, drivers can feel more confident knowing there is an additional layer of safety built into the vehicle's braking system. The other options focus on aspects that do not define the primary role of spring brakes. Enhancing overall braking performance or reducing wear on service brakes are not the primary functions; instead, those attributes are typically associated with the standard air brake system. Increasing stopping distance is contrary to the purpose of braking systems, which aim to shorten stopping distances for safety.