Patent GB-930201-A (GB)
IPC: E21D15/58
Abstract: 930,201. Mine roof supports. W. E. & F. DOBSON Ltd. Aug. 6, 1959 [Aug. 11, 1958; May 5, 1959 (2)], Nos. 25666/58, 15312/59 and 15411/59. Class 20 (2). An advancing extensible and contractible mine roof support comprises a roof supporting cantilever 2a and an auxiliary prop 11 having a U-shaped head 11a, Fig. 14, supporting the roof and through which the cantilever is adapted to slide when the roof support and cantilever are advanced, the auxiliary prop when contracted being adapted to be suspended and moved along the cantilever, being suspended by lugs 11b from the bottom flange of the cantilever. The auxiliary prop is pivoted at lie to the head 11a so that it can be tilted to pass over the coal conveyer 1 to support the roof ahead of the conveyer. This tilting may be effected by a pivoted arm 43, Fig. 14, the end of which abuts the cylinder 11d when the auxiliary prop is contracted, continuing contraction causing the prop, the head 11c of which is connected by a pin and slot 45 to the arm, to tilt as shown in dotted lines. The cantilever may project forwardly or rearwardly and have a waste stowing pipe suspended from it and a waste barrier mounted on the auxiliary prop. The roof support comprises two hydraulic props 4, 5 having a base 3 and a roof bar 6. Two supports are used side by side advanced in steps by a ram interconnecting them. The cantilever is forced against the roof by an hydraulic cylinder as described in Specification 885,293 and the props 4, 5 have intensifiers as described in Specification 890,644. The conveyer 1 is advanced by an hydraulic cylinder on the roof support. The extension and contraction of the roof supports are controlled by cam-operated valves, the rams for advancing the roof support and conveyer are controlled by disc valves. The auxiliary prop comprises a piston 11c, Fig. 7, in a cylinder 15, the pressure space PEC of which is supplied with liquid by a pipe 18 in the piston and a port 23 when the prop is to be extended, the prop being released by liquid in the annular space 20 between the piston and the cylinder supplied by a hole 19, the interior of the piston and a port 24. The pipe 18 may comprise a check valve 137, Fig. 26 (not shown) to prevent fall of pressure if an external pipeline should break. The auxiliary prop is controlled by a disc valve, Fig. 12 (not shown), in which the liquid supplied to the pressure space PEC passes a check valve which is opened by a cam on the valve control handle for the return of fluid from the space PEC. The auxiliary prop may be moved along the cantilever by hydraulic cylinders 171, 171a, Figs. 32, 36 (not shown), and the prop is supplied with liquid through the hydraulic cylinders. In this modification another auxiliary prop is mounted on a fixed pivot 165, Fig. 34 (not shown), on the end of a cantilever at the other end of the roof support, roof bars 365, Fig. 35 (not shown), being arranged one on each side of the cantilever. In Fig. 38 one roof support has two auxiliary roof bars 202, 203, one on each side of the cantilever 2a, each having an auxiliary prop 200 or 201 pivoted to it. The bars are connected by a channel 206 having flanges running between the flanges of the cantilever. The bars and props are moved along the cantilever by hydraulic cylinders and the props are tilted outwards to clear the conveyer by a cylinder and pistons 219. Specification 856,720 also is referred to.