GB1131962A - Improvements in or relating to planetary gear trains and hoists incorporating such gears - Google Patents

Abstract

1,131,962. Hoists. INGERSOLL-RAND CO. 12 Jan., 1967 [12 Jan., 1966], No. 1696/67. Heading B8B. [Also in Division F2] To promote even load division between, and correct alignment of, the planet pinions of a planetary reduction gear of an overhead hoist, pairs of planet pinions 27, 28 being splined on to shafts 21 rotatably mounted in a carrier 20, the splines of each pinion and/or shaft are crowned to allow each pinion to rock on its shaft, and the carrier 20 floats radially. The hoist (Fig. 1, not shown) comprises a reversible electric motor (5), a reduction gear and brake unit in a casing portion (3), and, in a casing portion (4), a sprocket 9 over which passes a chain (7) carrying a lifting hook (8). In the reduction gear, the planets 27 mesh a sun gear 17 integral with a shaft 15 driven by the motor shaft 12, and an internally toothed reaction annulus 35, while the planets 28 mesh an internally toothed ring gear 32 integral with a hollow shaft 10 to which the sprocket 9 is splined. A one-way sprag clutch 41 connects the shaft 10 to a sleeve 40 to which are splined brake discs 43. Discs 44 interleaved therewith are held against rotation by engagement with fixed longitudinal bars (37) (Fig. 3, not shown) which also engage cutouts (36) (Fig. 4, not shown) in the reaction annulus 35 to allow the latter limited rotational freedom. Ramps 50, Fig. 5, on one end of annulus 35 engage ramps 51 of casing 3. When a stationary load is supported by the hoist, the resultant torque on the annulus 35 rotates it in a direction causing the ramps 50, 51 to move annulus 35 axially rightwards, Fig. 2, to act via an extension 48, a sleeve 49, and a pressure-plate 46, to apply the brake. When the motor is run to lower the load, the torque on annulus 35 results in axial motion to release the brake, the load torque overrunning the motor torque causing the brake to be alternately applied and released. The pressure-plate 46 and a disc 52 are splined to the extension 48 to allow transmission, from the shaft 10 via the sprag clutch 41, of a load torque tending to apply the brake, to prevent coasting or slip of the load after the motor has been de-energized. When the load is raised, the shaft 10 rotates in the free-wheel direction of sprag clutch 41 so that the brake does not impede lifting.