| 摘要 |
<p>PREAMBLE TO DISCLOSURE Be it known that MALCOLM WAKE of Universal Works, Horbury, Wakefield, West Yorkshire WF4 5HR, England an Engineer having made an invention entitled: "IMPROVEMENTS IN MINE ROOF SUPPORTS" the following disclosure contains a correct and full description of the invention and of the best mode known to the inventor of taking advantage of the same. A self-advancing, hydraulically powered mine roof support of the kind comprising a base means, at least one roof beam, a plurality of hydraulically extensible chock legs extending between the base means and the roof beam(s) a shield provided at a rear of the support, a permanently loaded, force applying means operable in one direction only on the shield and on the roof beam(s) to apply restoring forces thereto, has both the chock legs and the shield inclined and displaceable towards, but not beyond, a vertical position by relative movement between a mine roof and a mine floor.</p> |
