GB623723A - Improvements relating to overhead cranes - Google Patents

Abstract

623,723. Overhead travelling cranes ; winding and paying-out apparatus. SOC. FRANCAISE DE CONSTRUCTION DE BENNES AUTOMATIQUES. April 8, 1942, No. 4619. Convention date, May 27, 1941. [Classes 78 (iv) and 78 (v)] In an overhead crane of the kind comprising a carriage movable to and fro along a track and carrying a hoisting cable controlled by a winch, an electric motor carried by the carriage is adapted to exert an additional force on the hoisting cable in its lowering direction so as to prevent excessive sag in this cable. Fig. 1 shows the application to a carriage which runs on a track 2 and is provided with a hoisting cable 4 operated by a winch at 21 and running over a pulley 3 on the carriage. When the carriage reaches the position in which a load is to be deposited and the hoisting winch rotated in the direction for lowering the load, a motor 6 on the carriage is operated automatically so as to drive the pulley 3 through belt or chain gearing 5 in the direction for lowering the load. Current is supplied to the motor through wires 7 connected to a member 8 which engages bars 9 secured to the track 2 and fed by a supply cable 18 connected to the controller of the hoist winch motor. This connection is such that the bars 9 are alive only when the winch motor is connected so as to drive the winch in the direction for unwinding the cable 4. A roller 11 on levers 10 is pressed against the cable 4 by a weight 12 or springs to ensure that the cable is driven by the pulley 3 without slip. The hoisting winch may serve to traverse the carriage in one direction and the counterweight in the opposite direction.