| 摘要 |
<p>1,247,152. Advancing mine roof supports. W. E. & F. DOBSON Ltd. 2 Jan., 1969 [9 March, 1968], No. 11623/68: Heading E1P. Mineral is removed from a face F of a mineral seam by successive traverses of a cutting machine 10 which thereby forms a gallery in which is disposed side-support structures 11a, 11b each of which has vertically spaced transverse jacks 14 for engaging the sides of the gallery, the structures 11a, 11b being moved forward alternately, step-by-step, by contracting the jacks of one of the structures and moving it forwardly while the other structure is held then moving the other structure while the first said structure is held. The structures 11 a, 11b are suspended from carriages 12a, 12b and moved relative to each other by jacks 17. The structure 11b has protective shields 18. More than two side-support structures may be provided.</p> |
