You need at least _____ psi to release the spring lock on brakes.

You need at least _____ psi to release the spring lock on brakes.

• A. 40 psi
• B. 60 psi
• C. 80 psi
• D. 20 psi

Answer: (B)

Spring brakes use powerful springs to hold the brakes on when air pressure is removed. To release those springs and allow movement, you need enough air pressure to overcome the spring force. In typical fire apparatus brake systems, that release threshold is 60 psi. So you must have at least 60 psi in the air brake system before releasing the spring brakes; below that, the springs may stay engaged and the vehicle may not release safely. The other numbers don’t match the standard release point, so 60 psi is the correct minimum. Always verify adequate air pressure on the gauges before releasing the spring brakes.

Spring brakes use powerful springs to hold the brakes on when air pressure is removed. To release those springs and allow movement, you need enough air pressure to overcome the spring force. In typical fire apparatus brake systems, that release threshold is 60 psi. So you must have at least 60 psi in the air brake system before releasing the spring brakes; below that, the springs may stay engaged and the vehicle may not release safely. The other numbers don’t match the standard release point, so 60 psi is the correct minimum. Always verify adequate air pressure on the gauges before releasing the spring brakes.