GB1135942A - Improvements relating to roof supports for mine workings - Google Patents

Abstract

1,135,942. Mine roof supports. K. M. GROETSCHEL. 7 March, 1966 [7 Dec., 1964], No. 49740/64. Heading E1E. [Also in Division F1] In a mine roof support comprising a base 71 having a plurality of telescopic hydraulic props 11, 14, 15 and 16 carrying roof-bars 47, one of the props 11 has an intensifier to produce a pressure, higher than the pressure fluid supply, in the prop chamber, the chamber being connected to provide a pressure higher than the setting pressure in at least one other prop. The prop 11 has a hollow piston acting as the cylinder for an inner prop 12 such that the pressure in the inner cylinder is intensified due to the greater area of the hollow piston. The hollow piston supports a yoke 65 supporting the rearward roof bars through posts 67; the rear ends of these bars being supported by the props 14, 15. The forward roof bars 47 are supported by the inner prop piston 12 and, optionally, by the prop 16. The rearward roof bars may have hinged extensions 42 actuated by a wedge and jack mechanism 43, 38. Advancement is provided by twin horizontal jacks within the base 71 coupled to the conveyor 34. In use a distribution valve V5 initially supplies pressure from an inlet 20 to props 12, 14, 15 and 16 until the preload determined by setting load valve V7 is reached. Pressurization of prop 11 to a pressure determined by setting load valve V7 and yield load valve V11, produces a higher pressure within prop 12, which pressure may be fed through selector valve V1 in sequence, or concurrence, to props 14, 15 and 16 to a pressure determined by yield load valve V11. Minimum pressure valves V3, V4 and V6 prevent retraction of all other props should one prop or pipe leak.