GB742850A - Improved device for supporting the roofs of mine galleries - Google Patents

Abstract

742,850. Pit-props. SOC. D'ETUDES HYDRAULIQUES POUR L'INDUSTRIE MINIERE, S. E. H. 1. M. Oct. 8, 1953 [Dec. 6, 1952]. No. 27732/53. Class 20(2). In a prop assembly for mine galleries of the kind which forms the subject of Specification 719,170, a horizontal hydraulic jack 7, Fig. 1, is connected between the telescopic sole members 3 and 4, the piston 7d, Fig. 3, of the jack 7 being coupled by its piston rod 7c to the sole member 3 and the cylinder of the jack 7 being coupled to the sole member 4 by a lost motion linkage which consists of a slotted member 7a secured to the cylinder anda bar 8 secured to the sole member 4 and having a roller head 8a slidable in the slot 7b of the member 7a. The jack 7 is in hydraulic communication with the lower ends of double acting vertical jacks 5, 6 supporting the telescopic roof beam 1, 2. When the jack 5 is lowered by admitting pressure fluid through a conduit 5h at its upper end, fluid in the lower end is forced into the right hand end of the jack 7, which thereby extends, and when the lost motion provided by the slot 7b has been taken up, causes the sole member 4 jack 5 and roof girder 1 to be advanced. Similarly when the jack 6 is lowered by admitting pressure fluid through a conduit 6h at its upper end, the jack 7 is retracted by fluid expelled from the lower end of the jack 6, which when the lost motion has been taken up, causes the sole member 3, jack 6 and girder 2 to be advanced. The pressure fluid is supplied by a rotary distributer valve, Fig. 10 (not shown) to the conduits 5h, 5b, 6h, 6b in sequence, during which the whole prop assembly advances. Alternatively a sliding distributer may be used. Additional conduits, not shown, are provided for returning fluid displaced by the pistons 5a, 6a and 7d, to the pump reservoir.