Safety device that detects fracture of the drive machine shaft.
Full Definition
Broken shaft detection monitors the integrity of the elevator drive machine shaft and triggers a safety stop if shaft fracture is detected. In geared machines, a fractured shaft can render the brake ineffective, leading to uncontrolled car movement. Detection methods include proximity sensors monitoring shaft rotation, torque monitoring, or mechanical coupling devices that activate the safety chain on shaft failure. This device is particularly important in older geared traction machines where shaft fatigue is a known risk. EN 81-20 requires equivalent safety levels by alternative protection methods in modern designs.
