Patent GB-1381303-A (GB)
Title: Hydraulic control system
IPC: E21D23/16
Filed: 1971-08-04
Abstract: 1381303 Advancing mine roof support circuits GEWERKSCHAFT EISENHUTTE WESTFALIA 4 Aug 1971 [4 Aug 1970 (2) 10 Oct 1970] 36708/71 Heading E1P [Also in Divisions Fl and F2] A hydraulic control system comprises valve devices actuable to control a hydraulic path therethrough, pressure medium conduits for connecting said valve devices between a number of consumer appliances and pressure medium supply and return lines whereby pressure medium can be fed to. or from one or. more of said appliances and via one of the valve devices when the latter is selectively actuated, a manually operable control device for actuating a selected valve device, further pressure medium conduits for connecting the control devices to the valve devices, at least some. of the valve devices each having two servopistons, each servo-piston having in turn its own associated working chamber, and the servo-pistons being adapted to. actuate the valve device when pressure medium is conveyed to the associated working chamber, one of the chambers of each of said devices being operably connected through one of the further conduits to said control device and the other of the chambers being operably and selectively connected to part of the system adapted to effect an automatic control sequence on said appliance. The control system of the invention is preferably applied to a mine roof support system comprising a series of assemblies each having four props 60, 60A actuated by a ram 62 connected to a conveyor, the props 60 being the forward props and the props 60A the rear props. The control valve, see Heading F2V, is depicted herein as having operating positions I..VII and is connected to a pressure conduit P and a return line R via a branch line P', R' respectively: The props 60 and the props 60A each have a common double-acting servo-control valve such as 63 with servopistons 63', 63" adapted to control the extension of the props under manual or automatic control respectively; robbing of the props being controlled by a valve 69 having servopistons 69', 69" which to-gether with pressurerelief valves 65, 65A are connected in the circuit as shown. The ram 62 is controlled by double-acting servo-control valves 73, 79 having servo-pistons 73', 73", 79', 79"; a relief valve 77 and a regulator 83 being arranged in the circuit for the ram as depicted. The regulator 83 controls a valve 85 connected in turn to a control conduit ST and to a reversing valve 86 incorporating a timing mechanism 88. In position III the props 60, 60A are extended and the ram 62 blocked off from the return line R to hold the conveyor fixed. In positions II and IV the ram 62 is extended to advance the conveyor and the props are robbed respectively, whilst, in position V the props are robbed and the ram 62 retracted to move the props up to the conveyor. In position I the rear props 60A are set against the roof independently of the front props 60 and in position VI the front props are likewise set independently of the rear props; simultaneous setting of all the props being effected in position VII. The assembly disclosed may be successively operated in association with other assemblies for detailed automatic control of which the Specification should be referred to. For modified arrangements in which the control arrangement involves a mine roof support assembly with two relatively movable frames and an installation in which the shifting rams for a group of assemblies are operated simultaneously Figs. 2 and 3 respectively (not shown), should be referred to.