GB197790A - Improvements in or relating to systems of control for lifts - Google Patents

Abstract

197,790. Lyons & Co., Ltd., J., Goddard, A., and Douglass, G. March 15, 1922. Electric push-button systems. - Comprises a motor control system in which the cage, on arrival at its end station, automatically opens the power circuit and operates a reversing switch in the same circuit, so that the cage is ready to start on its return journey directly the power circuit is again closed. A reversing motor 2 operates a cage 1 balanced by a counterweight 5. Limit switches 6, 7 are opened by the counterweight or the cage when the latter is at the bottom or top of its travel. A switch 8 for reversing the motor circuit is operated by the cage through stops 34, 35 on an endless rope passing round a pulley 31 controlling the switch 8. Press-button switches 37, 38 at the bottom and top floors are respectively in parallel with the switches 6, 7. Thus when the cage descends and reaches the lower floor the weight 5 operates the switch 6 and breaks simultaneously the circuit through the motor and an electromagnetic brake 39 held off when the motor is working. The cage is brought to rest by the brake and during its final movement operates the reversing switch which comprises rocking contact arms 21, 25. When the button 37 is pressed the open switch 6 is shortcircuited and the cage rises. The switch 6 is released by the counterweight almost immediately and closes automatically, so that the buttons need only be pressed momentarily. By providing intermediate circuit-interrupting switches and corresponding push-buttons the lift can be started and stopped at intermediate levels.