Abstract: An elevator system including apparatus for detecting mechanical damage to the elevator system, such as might be caused by an earthquake. A cable strung in the hoistway is reeved about a plurality of sheaves carried by the counterweight. Normal operation of the counterweight maintains a predetermined tension in the cable, which predetermined tension is used to maintain a switch in a first condition. Abnormal movement of the counterweight outside of its vertical travel path changes the tension in the cable and operates the switch to a second condition which modifies the operation of the elevator system.

Abstract: An elevator system including an elevator car and counterweight mounted for guided vertical movement in the hoistway of a building. A magnetically operated detector mounted on the elevator car cooperates with a magnetic shield disposed in the hoistway to noiselessly provide signals which indicate when the elevator car and counterweight are in a predetermined collision zone where collision is possible should the counterweight deviate from its normal travel path. The detector also provides signals when the elevator car and counterweight are outside the collision zone, which signals indicate the relative positions of the elevator car and counterweight.

Abstract: An elevator system including an interconnected elevator car and counterweight, motive means for driving the elevator car and counterweight, and apparatus for detecting mechanical damage to the elevator system, such as might be caused by an earthquake. An elongated member, such as an electrical conductor, or a conductor of electromagnetic radiation, is disposed along the vertical travel path of one of the movable components, such as the counterweight. The movable component includes a device which severs the elongated member in response to a predetermined horizontal movement of the movable component. A detector monitors the integrity of the elongated member, and it modifies the operation of the elevator system when the elongated member is severed.