GB896424A - Improvements in gripping devices for cylindrical and like objects - Google Patents

Abstract

896,424. Gripping rods. DOWTY ROTAL Ltd. Dec. 6, 1960 [Dec. 8, 1959], No. 41750/59. Class 78 (4). The jaws 15, 16, Fig. 1, of a device for gripping rod-like articles are power-operated by means 11 and locked closed by members 37, 38 operated by further power means 46 which lock the jaws after closure and unlock them before opening. As described, both power means are hydraulic rams and members 37, 38 wedge rollers 32, 34, Figs. 6, 7, between the inner surfaces 25 of the jaw members 15, 16 and cam surfaces 31, 35. To close the jaws, fluid is admitted through ports 50 and 56, Fig. 3, and exhausted through a port 55 moving a piston 24 to the left. This closes the jaws through links 43, 44 and pushes liquid past a valve 49 and out through the port 55. Simultaneously, liquid entering through the port 56 displaces a piston 47 to the right which pulls on links 43, 44 to turn members 37, 38 and lock the jaws in the closed position. The jaws are not prevented from closing by the locking members as the wedging action occurs only when the jaws tend to open. Alternatively the rollers 32, 34 can be spring-loaded into locking engagement and released by hydraulic pressure on the piston 47. To release the lock the ports 50, 56 are exhausted and pressure liquid supplied to the port 55. This holds the valve 49 on its seat so that the piston 47 only is displaced to the left to release the locking members. When the piston 47 is almost at the end of its travel it engages a circlip 53 and lifts the valve 49, thereby admitting pressure fluid to the piston 24 which is moved to the right and opens the jaws. The invention may be applied to the handling of drill pipes, collars and steel casings for oil wells.