In a braking system with spring brakes, what happens when air pressure is released?

In a braking system with spring brakes, what happens when air pressure is released?

• A. The brakes release
• B. The springs apply the brakes
• C. The system shuts down
• D. ABS engages

Answer: (B)

In spring-brake systems, air pressure holds the springs back and keeps the brakes released during normal operation. When that air pressure is released, the springs push the brake shoes against the drums, causing the brakes to engage. This is a safety feature: if the air supply fails, the springs automatically apply the brakes to stop the vehicle or hold it in place. The other options don’t fit because releasing air pressure does not release the brakes, ABS isn’t triggered by this pressure change, and the system doesn’t simply shut down.

In spring-brake systems, air pressure holds the springs back and keeps the brakes released during normal operation. When that air pressure is released, the springs push the brake shoes against the drums, causing the brakes to engage. This is a safety feature: if the air supply fails, the springs automatically apply the brakes to stop the vehicle or hold it in place. The other options don’t fit because releasing air pressure does not release the brakes, ABS isn’t triggered by this pressure change, and the system doesn’t simply shut down.