GB707051A - Improvements in or relating to pit props and like supports - Google Patents

Abstract

707,051. Hydraulic jacks. LAKE & ELLIOTT, Ltd., GILBERT, G., and NEWMAN, J. Oct. 16, 1951 [Oct. 31, 1950], No. 26535/50. Class 78 (3) [Also in Group X] In an hydraulically operated unit for attachment to a pit prop comprising a cylinder 4 in which works a piston 3, a reservoir 5, a pump plunger 31 operated by a rocker arm 20 and operating through inlet and outlet valves 37, 40 to supply fluid from the reservoir to the cylinder, a manual screwoperated release valve 46 for the cylinder and a supporting head 6 engaging the mine roof, part of the unit, either the cylinder or reservoir, is mounted within the end of the pit prop 1. In Fig. 1 the pump is contained in the piston 3, but in other modifications it is contained in the reservoir. In both cases modifications are shown with two pump plungers operated alternately by a double rocker arm, each plunger having its own inlet and outlet valves or with one plunger only. In the modification having the pump in the reservoir, the head 6 is supported directly by the piston 3 in the cylinder 4 which is above the reservoir 5. When the valve 46 is to be operated from a distance it is arranged to be closed by a spring bearing on the valve by means of a flanged sleeve which is adapted to be moved to compress the spring, to allow the valve to open, by a cord from a distance operating a lever acting on the handle 49 which may also be turned to compress the spring by screw means. Specification 701,446 is referred to.