| 摘要 |
<p>1,247,443. Advancing mine roof supports. KRAMPE & CO. FERTIGUNG IN BERGBAUBEDARF G.m.b.H. 26 Feb., 1969 [27 Feb., 1968], No. 10331/69. Heading E1P. In an advancing mine roof support assembly for a longwall working one of two neighbouring support units A is provided with a rigid waste-retaining shield 10 which on either side is connected to a folding waste-retaining screen 20 pivotally attached to a neighbouring unit 13, each unit 13 being additionally provided with a rigid shield 22. For details of shields and screen the Specification should be referred to.</p> |
