GB1094892A - Improvements in fluid flow control valves - Google Patents

Abstract

1,094,892. Valves. BONSER ENGINEERING Ltd. June 8, 1964 [June 13, 1963], No. 23515/63. Heading F2V. [Also in Division F1] A valve controlling the supply of pressure fluid to a pit-prop automatically repositions the prop if roof breakaway occurs. The valve comprises a body 1 having a threaded bore 2 which receives an insert 5 having radial ports 13, 15 communicating with annular recesses 12, 14, respectively, and providing a valve seat 8 for a closure member 6, the stem of which engages a spindle 7 which co-operates with a cam 23 mounted on a spindle 24 connected to a handle 25. Mounted on the body is a casing 32 defining a cavity 33 housing a distributer member 35 which is attached to, and rotatable with, a lever 39, and which is provided with two passages 36, 37 (37 being a restricted passage) and a recess 38. The body is provided with a pressure fluid supply passage 26, an exhaust passage 29, a passage 30, 31 connected to the space above the piston of the pit-prop, a passage 28 connected to the annular recess 12, a passage 27 connecting the annular recess 14 to the space below said piston and a passage 16 provided with a relief valve (not shown). In operation, to raise the piston of the pit-prop, lever 39 is moveed to align passages 28, 36, and cause the recess 33 to cover passages 29, 30, thus connecting the space below the closure member to the supply and passage 30 to exhaust (Fig. 5). Lever 25 is then actuated to lift the closure member and allow fluid to raise the piston. This lever is then released, and lever 39 is returned to the central position, in which position the restricted passage 37 aligns with passage 28 and passage 36 is sealed, the other connections remaining unchanged. If the roof should break away above the prop, the pressure above the closure member falls and the closure member 6 is unseated due to the pressure difference thereacross, thus allowing further fluid to flow to the space below the piston to raise the latter until it again contacts the roof. To retract the piston, lever 39 is positioned to connect passage 28 to exhaust and align passages 36 and 30, the valve is then opened by means of lever 25 and the piston retracts with the aid of fluid passing to the space thereabove.