| 摘要 |
494,186. Mining, quarrying, etc.; mine-roof supports. MAVOR & COULSON, Ltd., and GULLICK, G. M. June 12, 1937, Nos. 16357, 16358, and 34804. [Class 68 (i)] [Also in Group X] In mining, quarrying and the like, an undercut a and an overcut b of greater depth are made in the face, roof beams 2 are inserted to the inner ends of the overcut and supported at their outer ends by props &c. 4, and the coal is broken away, as by hydraulic pressure applied in either the undercut or the overcut, the extra depth of the roof cut leaving a ledge on which the roof beams remain supported. A conveyer C may be arranged on the face side of the props 4 and receive the broken down coal from a mechanical loader. The undercut may be made first, or both cuts may be made simultaneously as by a machine D, Fig. 7, with an undercutting member 5 in advance of, and of less reach than, a vertically adjustable overcutting member 6. In Fig. 9, an undercutting machine D<1> has parallel bars 11 supporting a plate 13 on which an overcutting machine D<2> is adjustably supported by independent jacks 12, the bars 11 and parts carried thereby being adjustable, as by screw means, to vary the lead of the undercutting machine, the parts then being locked together. The adjustments may be made by power. The props 4 may be of H-section, with welded brackets 14, Fig. 11, on each side for supporting the roof beams. The machines used may be of disc, chain or bar types, or any two in combination. Specification 411,256 is referred to. |
