| 摘要 |
The invention is concerned with mine-roof supports, especially self-advancing mine-roof supports and provides a support comprising a base, a shield inclined downwardly and rearwardly towards the rear of the base and pivotally attached to said base, a roof-engaging canopy pivotally attached to an upper part of the shield, hydraulically; extensible prop means operatively positioned between the base and said shield, and hydraulically-extensible prop means operatively positioned between the base and the canopy. In some preferred embodiments of the invention the shield is a completely non-roof-engaging member and the pivotal connection between the shield and the baseis such that raising and lowering of the shield, by the prop means between said shield and the base, does not involve material angular displacement of said prop means. The pivotal connection between the canopy and the shield conveniently includes a debris excluding joint between said canopy and shield. The space between the prop means supporting the shield and the prop means supporting the canopy is generally designed to provide a safe walkway for miners. The forward end of the canopy may be provided with an extensible and retractable extension bar and/or with a mineral-face-supporting sprag or plate. The support may have a side anti-flushing shield at at least one of its sides and said anti-flushing shield may be extendable and retractable laterally with respect to the support.
|
