GB186657A - Improvements in or relating to hoisting and luffing mechanism for cranes - Google Patents

Abstract

186,657. Ransomes & Rapier, Ltd., and Lewis, R. S. June 2, 1921. Jib cranes.-Comprises arrangements of hoisting and luffing gear for cranes of the type in which both hoisting and luffing gears are connected to a single source of power so as to be driven separately or simultaneously, the gearing not in use being automatically braked. In the present construction a driven shaft, normally braked by a stationary member, is coupled to a coaxial driving-shaft, the axial movement of the clutch member progressively releasing the brake and engaging the clutch elements. In the form illustrated in Fig. 1, a worm shaft A<1>, connected to the source of power, drives the hoisting-drum D directly and is fitted with the sliding element C<2> of a friction clutch for coupling it to the coaxial worm shaft B for driving the luffing-drum. The engaging movemsnt of the clutch moves the shaft B axially against the pressure of the load to release the clutch element C<1> from the fixed brake cone C, the brake being re-applied automatically as soon as the clutch is relieved. Preferably the drums are wound so that the raising of the load is accompanied by a lowering of the jib to give approximately horizontal traverse of the load during luffing. A solenoid C<5> may be used to operate the clutch. In a modification, the clutch and brake surfaces are flat discs instead of being conical. In a further modification, Fig. 3, two geared parallel shafts J, K are employed for driving the hoisting and luffing drums respectively, each shaft being fitted with clutch-and-brake mechanism similar to that shown in Fig. 1.