GB527138A - Improvements in pulley-hoists - Google Patents

Abstract

527,138. Pulley-hoists. MUSUDA, K. May 31, 1939, No. 16085. [Class 78 (v)] In a geared pulley-hoist a clutch 17, Fig. 1, is provided by means of which the reduction gearing 12, 15b, 15a and 9 can be put out of action when it is desired to adjust the lifting chain. The chain wheel 2 for actuating the hoist is mounted on the threaded end 3 of the shaft 1 and can be moved longitudinally thereof to an extent limited by plates 8, 8a. A pawl 6 mounted on the casing 21 engages a ratchet wheel 4 which is mounted on a boss 5 of the wheel 2 between friction rings 7. The chain wheel 13, around which the hoisting chain passes, is rotatably mounted on the shaft 1 and carries the gear 12. The gear 9 is also free on the shaft and is urged against a shoulder 11 by a spring 10. A slidable coupling member 17 keyed to the shaft 1 has three coupling projections 17a, Fig. 4, on one side and a circumferentially disposed coupling member 17b on the other side. These coupling members co-operate with corresponding members 9a, 12a on the gears 9, 12, respectively. A groove on the member 17 receives the forked end of a pivoted arm 18 which is pulled to the right by a spring 20. If no load is attached, or if the load is light, rotation of the wheel 2 in the lifting direction drives the wheel 13 through the shaft 1, coupling member 17 and gear 12. If the load is heavy, the contact surfaces 12a, 17b slip over each other and the member 17 is forced to the left, thereby engaging the projections 9a, 17a and causing the wheel 13 to be driven through the reduction gearing. When the hoisting chain is to be lowered without any load attached, or supporting only a light load, the wheel 2 is rotated in the opposite direction and moves axially until it bears against the end plate 8a. Since the contact surfaces 12a, 17b are again in engagement, the wheel 13 is rotated at the same speed as the wheel 2. If the load runs backwards during hoisting, the reverse rotation of the shaft 1 will cause the wheel 2 to move towards the plate 8 and to be coupled by friction with the ratchet wheel 7. The pawl 6 prevents rotation of the ratchet wheel, and the movement of the load is arrested.