GB1082257A - Bracing device particularly suitable for use at the end of a face conveyor at a coal face where a coal plough is employed - Google Patents

Abstract

1,082,257. Advancing mine face conveyers. H. BEUKENBERG, H. BEUKENBERG and K. BEUKENBERG, [trading as MASCHINENFABRIK GLœCKAUF GœNTHER KLERNER]. Aug. 17, 1964 [Aug. 17, 1963], No. 33553/64. Headings B8A and B8J. A bracing device for the end of a face conveyer, in which telescoping hydraulic props braceable between the floor and roof and preferably tiltable, is characterized in that a signal is given when the props are so far extended that, owing to insufficient roof contact, efficient bracing is impossible. As illustrated in Figs. 1, 2 (not shown) the bracing device is associated with a free conveyer (1) and comprises a counter support (2) with tiltable telescopic props (3), (8) each with hinged caps (9). The driving station of the conveyer (1) is connected with a slide guide (4) enclosing the counter support (2). The slide guide (4) with the counter support (2) and the conveyer (1) are alternately movable in the bace advancing direction while reciprocally guiding one another, by a double-acting hydraulically operated cylinder (5). A doubleacting hydraulic tensioning cylinder (6) is provided. Fig. 3 shows an inner prop 11 with a piston 12 having a collar 22 arranged to engage in a control chamber 23. When the inner prop 11 is extended driving medium displaced above the piston 12 escapes through a conduit 29. Prior to reaching the upper end position the control chamber 23 is closed by the collar 22 and driving medium trapped in the chamber 23 is forced through a conduit 24 to act upon a spring- loaded control piston 25 to open a shut-off member 26 and connect a compressed-air supply to a signal whistle 28. Instead of a compressed-air supply a cartridge of compressed gas may be pierced by a pointed extension on the piston (25) (Fig. 4, not shown). Figs. 5, 6 show a further embodiment in two different operating positions. In Fig. 5 driving medium from a pump is fed through a conduit 31 and a valve 38 to extend an inner prop 11 with a piston 12, driving medium above the piston 12 returning without pressure to the pumping unit through conduits 35, 36. When the inner prop 11 is fully extended (Fig. 6) the piston 12 lifts a control member 14 to open a back-pressure valve 33 to allow the driving medium to circulate freely through conduit 32 and control chamber 23 to conduits 35, 36 and thus back to the pumping unit. At the same time back-pressure valve 38 closes to prevent driving medium returning from below the piston 12. As a result a bracing pressure cannot be built up in the chamber below the piston 12 and a pressure gauge 39 indicates a considerable drop in pressure as a warning signal. The inner prop 11 may be retracted (Fig. 7, not shown) by applying driving medium to conduit 36 which closes a valve 34 and acts on a differential piston 37 to open the back-pressure valve 38. As a result the piston 12 is forced down, driving medium below the piston 12 returning to the pumping unit through the valve 38 and the conduit 31.