GB130167A - Improvements in Worm Geared Hoisting Appliances. - Google Patents

Abstract

130,167. Vaughan, W. H., and Wood, F. July 30, 1918. Winches; geared pulley-hoists; brakes and retarding-apparatus; driving-gear; regulating and control-transmitting gear; selfsustaining gear. - In wormgeared hoisting-appliances of the kind in which the load is raised and lowered by a chain passing over a sprocket or by a rope coiled upon a drum, such sprocket or drum being controlled automatically and provided with a sustaining brake for the load, and, further, in which the hand chain wheel or actuating handle remains stationary while the load is lowered by gravity, means are provided for separating the gravity lowering controlling brake from the hand operated chain wheel by the same movement which releases the load sustaining brake and allows the load to descend under full control while the hoisting means remain stationary. During hoisting, teeth d<1> on the chain wheel d engage teeth e' on the controlling brake disk e which is slidably but non-rotatably mounted on the worm shaft c', and provided with centrifugal brake blocks f. A groove in the boss of the disk e is engaged by a fork p mounted on the end of a rod o<3> which is connected to one arm of a bell-crank lever o mounted on the frame. The other arm of the lever o is connected by a link o<2> to the releasing lever m of the self-sustaining brake which is of known construction and comprises a boss h fixed on the shaft c', a loose friction disk i and a retaining ratchet j. On depressing the lever m, the teeth d<1>, e<1> are first disengaged and then the screw k is actuated to release the self-sustaining brake. On releasing the lever m, the brake is reapplied and the teeth d<1>, e<1> re-engaged by a spring s.