“Spring-applied, power-released” describes a brake design where mechanical springs apply braking force by default, and external power is used only to release the brake for motion. In other words, the brake is naturally engaged (applied) when unpowered. To run the crane, a release mechanism—electromagnetic, hydraulic, pneumatic, or electro-hydraulic—overcomes spring force to open the brake.
This architecture is the foundation of a fail-safe brake system, widely used on crane hoists because it protects against power loss. If a blackout, emergency stop, or control failure occurs, the brake automatically returns to the applied state, helping prevent load drop or runaway movement.
For crane owners and engineers, the key advantage is predictable safety behavior under fault conditions. The key responsibility is correct selection and maintenance: air gap settings, spring condition, friction material, and release force must remain within specification to ensure the brake truly delivers fail-safe performance over its service life.