| 摘要 |
<p>1517711 Control of self advancing roof supports GULLICK DOBSON Ltd 17 June 1975 [20 Aug 1974] 36490/74 Heading E1P A self-advancing roof support having means for controlling the advance thereof comprises, a manually operable control valve 10 and an automatic sequence control valve 11 operable in response to a control signal from a position remote from the support, each control valve controlling the advancing steps required; isolating valves 13 to 17 enabling either one of the control valves to effect operation of the support independently of the other; and a control signal generator (51), Fig. 2 (not shown), manually operable to supply a control signal to the automatic sequence valve of another support. The shuttle isolating valves 13 to 17 in the automatic control valve 11 allow the overide of the automatic system by the manual control valve 10. Remote automatic operation is initiated by a hydraulic signal from an adjacent support applied to ports 18 or 22 of pilot valve 9. Non return valves 36, 37, 38 are opened by strikers 33, 34, 35 to lower props 39, 40, 41 and ram 43 is retracted and, when fully retracted, operates a striker valve 44 which initiates the automatic re-setting of the props 39, 40, 41 via the non return valves 36, 37, 38. An outlet line 53 may be provided to initiate automatic operation of an adjacent support. The manual control signal generator (51), Fig. 2 (not shown) comprises spring-loaded pistons and cylinders controlled by a 'dead man's handle' (52), and can be used to initiate the automatic advance of supports on either side of the support on which it is mounted. For Figure see next column</p> |
