GB191404294A - Improvements in and relating to Electric Hoists, Cranes, Winches and the like. - Google Patents

Abstract

4294. Wilson, D. Feb. 19. Motors, controlling.-A winding or hoisting apparatus comprises, in a single unit, an electric motor and planetary reducing-gear so arranged that the movement of a normally stationary member of the gear applies a brake to the driven shaft when the descending load tends to overrun t h e motor; a separate electromagnetic brake is operated by the motor controller. The shaft 2 of the electromotor 1 carries a pinion 3 engaging planetwheels 5, 5<1> mounted in a carrier 8. Smaller planet-wheels 6, 6<1> rigidly secured to the wheels 5, 5<1> engage an internally-toothed rim 7, which is capable of only a slight longitudinal and axial motion relatively to the fixed casing. A pinion 9 secured to the planet-carrier 8 engages a pair of pinions 10, 10', which mesh with a fixed ring 26 and are mounted on a disk 12 secured to the drum 13. On the end of the motor shaft 2 are feather-keyed a series of brake disks 14 placed alternately between disks 15 attached to the casing. The brake is normally applied by a spring 21 and is withdrawn, when current is supplied to the motor, by an armature 20 attracted by a coil 23. The automatic brake is formed of metal disks 37 attached to the casing and fibre disks 29 carried by a ring 30. This ring 30 is connected by a ball or roller clutch to a rotary block 33, and is arranged to turn only during the lowering of the load. If, during lowering, the load tends to overrun the driving-gear, the pressure on the toothed ring 7 is reversed, and, in moving backwards, cam-surfaces on the ring engage a stationary roller 27 and cause the ring to move axially and to apply pressure to the brake disks 29, 37. In a modification, the drum is arranged on an auxiliary shaft driven by chain-and-sprocket gear from the final member of the epicyclic train.