| 摘要 |
<p>A B R I D G E M E N T This invention provides a mine roof support in which the cover, or canopy, is connected to a framework in such a way that the canopy can tilt relatively to the framework both in the fore-and-aft sense of the support and form side to side of the support. Thus, even though the frame work can not tilt relatively to the base, the cover can nevertheless tilt to take up irrugularties in the lie of the roof.</p> |
