| 摘要 |
A roof support, suitable for use in mines, includes a floor-engaging structure, extendible and contractible prop means carried by that structure, and a roof-engageable canopy supported by the prop means. The canopy comprises a main portion and an extension portion, each of which includes a plate member the upper face of which is engageable with the roof. Fastening means, which are provided for rigidly connecting the extension portion and the main portion together, include at least one connecting member adapted to lie within the thickness of the plate members, or substantially so.
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