GB620999A - Improvements relating to winding or hoisting arrangements - Google Patents

Abstract

620,999. Locking and unlocking lift cages. ECCLES, W., LAMB, E. LE L., FLOYD, S. A., and METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. Feb. 7, 1947, No. 3737. Drawings to Specification. [Class 78 (iii)] In a protective system for winding and hoisting arrangements the system comprises in combination a switch mechanically interlocked with the keps and a switch operable by movement of the winding gear, the said switches being arranged so that if the keps have not been withdrawn from under the cage which is at bank movement of gear to lower the cage causes the safety circuit to be broken thus cutting off the power supply and applying the emergency brakes. In the preferred embodiment a kep interlock switch, a headgear limit switch and optionally a clutch interlock switch, which is closed when the clutch is out, are provided for each cage and in operation the group of switches controlling the cage being raised is short circuited by a directional switch, the arrangement being such that the grouped switches control two indicating lamps and two relays, both of which latter must be closed if the safety circuit is not to be broken, said safety circuit being provided with switches, normally open, which can short circuit the relay contacts. In another embodiment relays are not used and the switches are connected directly in the safety circuit. In a further embodiment both groups of switches operate one time delay relay which is arranged to short circuit the directional switch when either set' of keps are withdrawn, and a further switch which can short circuit the directional switch is arranged to be closed when the winding gear is stationary. The circuit diagrams are shown in the Specification.