Patent ID: 7819229

Claim:
An apparatus in an elevator for detecting and stopping an uncontrolled movement of a car when a machine brake intended to keep an elevator car immovable is on, the apparatus comprising: a motion detector configured to detect uncontrolled movement of the car when a machine brake is already actuated and to detect a length of the movement when the machine brake is on, said motion detector including a gripper arranged to grip an elevator component moving with the car immediately when the machine brake is on or after a predetermined delay after the machine brake is on, said motion detector being configured to use the gripper for detection of the length of the uncontrolled movement of the car; a stopping device configured to stop the uncontrolled movement of the car when the length of the uncontrolled movement of the car detected by the motion detector reaches a predetermined distance after the gripper grips the elevator component during an on period of the machine brake, thereby stopping the uncontrolled movement of the car; and switches or limits placed at positions above and below the gripper, said switches or said limits being arranged to activate the stopping device.