GB754107A - Mine roof supports - Google Patents

Abstract

754,107. Hydraulic pit props. MINING ENGINEERING CO., Ltd. May 13, 1953 [May 27, 1952 ; June 23, 1952], Nos. 13462/52 and 15807/52. Class 20(2). [Also in Group XXIX] Energy derived from pressure on yielding mine roof supports due to roof subsidence is stored and used to supply mechanised power to mining implements. In one modification an hydraulic pit prop has a hollow ram 2, Fig. 1, serving also as a reservoir in which is housed an hydraulic accumulator 4 and a rotary valve 7 having passages to connect the prop cylinder 1 through a tube 10 to the accumulator so that when the prop takes the weight of the roof the accumulator is charged. To release the prop the valve 7 is turned to connect the cylinder 1 by a passage 11 to the reservoir and to shut off the accumulator and when the prop is set in a new position it is engaged with the roof by a hand pump 13 and the final supporting pressure is furnished by the accumulator which is connected through the valve 7 to the cylinder 1. The accumulator comprises a piston 6 containing a spring which may be air. In another modification the combined ram and reservoir 22, Fig. 2, is provided with a piston head 23 below which extends a skirt 25 acting as a limiting' stop and containing an auxiliary cylinder 27 having a piston 29 connected by a hollow piston rod 30 to a piston 33 in the ram 22. The accumulator 21 is in the lower end of the cylinder 20. This prop is first set up by compressed air admitted at 35 above the piston 33, which forces liquid from the ram reservoir 22 through the hollow rod 30, the cylinder 27, the control valve 37 to the cylinder space below the head 23 to extend the ram 22 against the roof. The valve 37 is then turned to connect this cylinder space to the accumulator which is thus charged by subsidence of the mine roof. To release the prop the valve 37 is turned to connect again the cylinder space to the reservoir via the auxiliary cylinder 27. The pressure in the accumulator is then used to reset the prop by turning the valve 37 to connect it to the upper side of the piston 29 and to connect the lower side of this piston to the cylinder space. The piston 29 and thus also piston 33 are forced down and the piston 33 forces fluid through the rod 30 cylinder 27 to the cylinder space to set up the prop by acting on the differential areas of the ram provided by the extension 25. The valve 37 is now turned to connect both sides of the piston 29 to the reservoir and to connect the accumulator direct to the cylinder space to apply its force to the full area of the ram 22. In Fig. 3 (not shown) a conveyer is moved by pressure fluid from the accumulator. In Fig. 4 (not shown) these props move each other forward alternatively by crossed links 45 having hydraulic rams 46 operated by pressure fluid from the accumulator of one of the props.