GB1037174A - Improvements in mine roof supports - Google Patents

Abstract

1,037,174. Advancing mine roof supports. COAL INDUSTRY (PATENTS) Ltd. May 3, 1963 [March 9, 1962], No. 9200/62. Heading F1P. In a mine roof support system comprising a plurality of advanceable fluid pressure operated support frames extending along the working face of a mine and each including support props 2, at least some of the frames are each connected to a face conveyer (not shown) by a double-acting ram 17 which normally advances the conveyer towards the working face, but when extended a predetermined amount initiates the advance of its associated frame. Each frame has an associated valve box 16 connected by a branch line 28a to a pressure supply line 28 and by a conduit 32 to a return line 29. The valve box 16 comprises a two position valve 22 having ports 23-26 and a sliding piston 21, the position of which is determined by the extension of the ram 17. As shown the props 2 are supporting the roof, pressure fluid being supplied to the lower ends of each prop cylinder 2a through branch line 28a, conduit 30, port 26 and through each of four pressure operated non-return valves 34. Simultaneously pressure fluid passes from the port 26 through a further pressure operated non- return valve 35 to extend the ram 17 and thereby advance the conveyer. The ram contracting side of ram 17 and the upper ends of each prop cylinder 2a are connected through respective conduits 42, 41 and the port 24 with the return line 29. When the ram 17 is nearly completely extended a lost motion device 18, 20 associated therewith ceases to operate and the piston 21 is moved to the left, whereby, provided pressure operated non-return valves 33 are open, pressure fluid passes from the branch line 28a through port 25 to act on the pistons 34a, 35a of the pressure operated non-return valves 34, 35 and also passes to the conduits 41, 42 to pressurize the upper ends of the props 2 and contract the ram 17. The valves 34, 35 therefore open to allow fluid to pass from the ram 17 and the lower ends of the cylinders 2a through the port 23 to the return line 29. The non-return valves 33 are subjected, through conduits 39a, 40a to the pressure prevailing in the props of the two adjacent support frames whereby advance of a frame is prevented in the event of an adjacent frame being in a non-supporting condition. Contraction of the ram 17 advances the frame until the piston 21 is returned to its frame supporting position wherein conduits 39, 40 are pressurized thereby opening the valves 33 of the two adjacent frames to permit their subsequent advances. Pressure relief valves 36, 37 are provided. The valve 22 may be a rotary valve and the two valves 33 may be combined.