A mechanical or electronic device that caps the maximum torque the door motor can apply, limiting closing force to safe levels.
Full Definition
The elevator door torque limiter is a protective mechanism ensuring the door motor cannot exert more than the maximum permissible closing force defined by EN 81-20 (150 N static, kinetic energy ≤10 J). Mechanical torque limiters use a slip clutch between motor and drive pulley, disengaging when torque exceeds a preset threshold. Electronic torque limiters rely on the door controller monitoring motor current and cutting drive when the current threshold indicating the specified force is reached. Both types must be calibrated and tested periodically. The torque limiter is also important in entrapment protection: if a passenger is caught between the closing panels, the limiter prevents crushing injury. Calibration records must be maintained as part of the safety documentation.
