GB467348A - Improvements in or relating to electrical controlling means for lifts - Google Patents

Abstract

467,348. Controlling - apparatus for lifts. EXPRESS LIFT CO., Ltd., and STEVENS, R. J. Jan. 8, 1936, No. 689. [Class 78 (iii)] The floor of a lift cage is supported on material which changes its electrical resistance when subjected to pressure by a passenger entering the cage, the change being utilized to operate controlling-means whereby the lift may be started. Fig. 1 shows the central area 4 of the floor mounted in a recess on piles of carbon resistance-blocks 5 and covered by a flexible dust-excluding rubber sheet 9 extending over the whole of the floor. The members 5 are connected in parallel through trailing cables 6 with a battery 7 and relay 8. The latter may serve to put the motor circuit into condition for starting the lift when the push-buttons are pressed, and may work in conjunction with means for ensuring that the well and cage doors are both closed. It may also serve for such additional functions as lighting a lamp in the cage. As examples of methods of fitting up the relay, a current passing through it and the blocks 5 may be balanced when the lift is unloaded, and the balance disturbed by the loading of the cage, or the members 5 may be connected in series to the primary of a transformer, and a steady current passed therethrough so that a change in the current caused by loading the cage causes a momentary induced current in the secondary of the transformer which effects the control. In a third arrangement, the blocks may be included in one arm of a Wheatstone bridge, with the relay across the diagonal.