GB724513A - Improvements in and relating to lifting appliances - Google Patents

Abstract

724,513. Garage lifts; fluid-pressure lifting apparatus. BRADBURY & SONS, Ltd., J., and POWELL, V. Nov. 2, 1951 [Nov. 15, 1950], No. 27983/50. Classes 78(2) and 78 (3). In a vehicle hoist as described in Specification 724,511 means are provided to immobilize the hoistdriving mechanism in the event of one or more of the cables 11 breaking or otherwise becoming slack. As shown, the limit switch 51, which is in the circuit of the electricmotor-driven pump (not shown) supplying fluid to the lifting ram (also not shown), and which is allowed to open and so deenergize the pump motor when a rod 52 is raised at the upper limit of travel of the platform, is also opened when any of the cables become slack. A shaft 82 mounted adjacent the cable anchor 12 is rigidly connected with a switch-actuating lever 87 and carries four rope-engaging arms 80, any one of which, when rotated clockwise by a spring 83, rotates shaft 82 and opens switch 51. These arms 80 are mounted on shaft 82 with a lostmotion coupling that allows the shaft to move clockwise freely relative to the levers so that on the breakage of one cable the mechanism is free to operate without movement of the other three levers. When used in conjunction with catch gear as described in Specification 724,512, the permissible movement of arms 80 is so limited that after their operation the cable is sufficiently slack to operate the catch gear. In various modifications (not shown) the arm 87 is used to open a valve, or to disengage a clutch, to immobilize the driving mechanism.