GB1024167A - Roof support assembly suitable for use in mines - Google Patents

Abstract

1,024,167. Advancing mine roof supports. DOWTY MINING EQUIPMENT Ltd. Feb. 11, 1965 [Feb. 14, 1964], No. 6299/64. Heading F1P. In a mine roof support assembly wherein a roof support, Fig. 1 (not shown) is advanceable towards an anchorage e.g. a conveyor 3 by an hydraulic jack 2 and the roof support comprises a roof beam 10 carried on hydraulic props 5 mounted in resilient rubber bushes 7 provided in a floor skid 4, the props 5 are caused to pivot about their bushes and thus operate a control valve 13, in the event of the roof beam encountering an obstruction during advance, whereby the props are caused to lower or lower at an increased rate. The hydraulic circuit controlling the roof support, Fig. 2 (not shown) comprises a manually operated valve 14, a prop release valve 18 and a prop resetting valve 28. To advance the roof support the valve 14 is moved to a position in which a line 16 connected to the jack 2 is pressurized from a main 15. Since the props are supporting the roof, advancement does not occur until the resulting pressure builds up in the line 16 acting via a line 19 opens opens the prop release valve 18. When the props have been released a certain amount the jack 2 commences to advance the roof support and the consequent fall in pressure in the line 19 allows a spring 32 to close the prop release valve 18. If the roof beam 10 meets an obstruction the control valve 13 opens and pressure fluid from the line 16 passes via lines 21, 25 to re-open the prop release valve. When the support has fully advanced a valve 26 actuated by complete retraction of the jack 2 causes pressurisation of a line 27 to maintain the prop release valve closed and to open the prop re-setting valve 28 and thus connect the props to the main supply 15. Finally the valve 14 is returned to the position shown whereby the prop re-setting valve returns to its original position, non-return valves 31 preventing escape of fluid from the props. To advance the conveyer the valve 14 is moved to its third position to cause extension of the jack 2. In a modification, Fig. 4 (not shown), the circuit is provided with a pair of prop release valves, one of which is loaded by a weak spring to allow the props to be continually released at a slow rate when the line 19 is pressurized, the other of which is operable only in response to operation of the control valve 13 to effect an increase in the rate of release of the props. The valve 13 may also cut off the supply to the advancing jack 2 when operated and may direct fluid to the props in order to cause release thereof under power.