GB967164A - Mine roof support systems - Google Patents

Abstract

967,164. Hydraulic apparatus. COAL INDUSTRY (PATENTS) Ltd. Oct. 12, 1960 [Oct. 12, 1959; June 16, 1960], Nos. 34500/59 and 21211/60. Heading F1P. In an advancing mine roof support system comprising a series of hydraulic prop units each provided with a double-acting ram connected to a conveyer, means are provided to jointly operate the rams for advancing the conveyer and then advance each prop unit in turn when the adjacent unit is in the support position. The props 2, 3, are fed with pressure fluid from a circuit including a conduit 17, a check valve 21, a control valve 22 and a relief valve 24. The ram 5 is controlled by a valve 25 and energized through a pressure line 19 to advance the conveyer. To advance the props pilot pressure is fed through a conduit 20 to spaces 29, 31 in the valves 22, 25 to displace their plungers and connect the props and the underside 27 of the ram 5 with the exhaust line 18, the other side 33 of the ram being connected to the pressure line 17 to advance the props. As the ram reaches its limiting position it moves the plunger 36 of a valve 16 to connect the pressure line 20 with the underside of the valve 22 and thereby re-connect the props with the pressure line 17. A valve 40 subjected to the pressure within the props is incorporated in the circuit as shown to reset the valve 25, the prop pressure being also transmitted through a conduit 45 to a second prop unitsaid conduit 45 corresponding to the conduit 20 of the present unit. In a modification, the plunger of the ram 5 is adapted to operate a limit switch connected in series with a pressure switch operable when the props are fully set to initiate operation of the next support for details of the hydraulic and electrical circuits, Figs. 4-7 of the Complete Specification (not shown) should be referred to. In a modification, see Fig. 1 of Provisional Specification 21211/60 (not shown), the unit includes solenoid operated valves having additional manual control means, the control arrangement consisting of an hydraulic leg control valve, an hydraulic ram control valve, an hydraulic leg relief valve and a non- return valve for details of which the Specification and Application 18862/60 should be referred to, further modifications being disclosed with reference to Figs. 2 and 3 of said Provisional Specification. Specification 933,979 also is referred to.