GB1380799A - Lowering devices - Google Patents

Abstract

1380799 Winding drum retarding devices G L M DU MESNIL DU BUISSON 19 Sept 1972 [21 Sept 1971 24 Jan 1972] 43365/72 Heading B8B An apparatus for the controlled lowering of a load on the free end of a cable 6 depending from a drum 5, comprises drum rotation retarding devices each including opposed pistons 21 in a common cylinder 20, and engageable with a cam 8 secured to the inside of the drum, the cylinder being held stationary relative to the drum whereby fluid in the cylinder 20 is forced through a restriction 23 from one chamber 25 to the other 24 as the pistons are moved by the cam 8. The cylinders 20 are secured to a shaft 7 on which the drum is freely rotatable and to which a device handle is secured, a pin 18 on the handle 4 being selectively engageable with a frame 3 of the apparatus to lock the shaft 7 during lowering of a load. The force between the cams 8 and the pistons 21 is sufficient that the drum 5 may be driven by the handle 4 to wind in the cable 6 when it is not loaded, alternatively, a spring may be provided for automatic rewind of the cable once unloaded. In the embodiment of Fig. 3 (not shown), each cylinder houses one piston which projects from each end of the cylinder and a restriction orifice within the piston permits fluid flow between two chambers formed in the cylinder by the piston. Alternatively, the cams may be secured to the drum shaft and the piston and cylinders secured to the drum. In a further embodiment, the cylinders are arranged axially of the drum and the cams comprise discs arranged transversely of the drum shaft.