| 摘要 |
<p>A mine roof support comprises a plurality of hydraulically extensible chock legs attached at their upper ends to one or more elongate roof bars by means of a projection on each chock leg passing through an aperture in the underside of the roof bar(s) to be located in articulated manner in any one of a plurality of positions along the roof bar(s) and within the roof bar(s) by abutment means.</p> |
