| 摘要 |
<p>Braced gutter profile sections, to narrow the span width of unpropped caps or I-profiled beams, are incorporated in the pref. multi-piece pit prop for galleries. Use is made of a prop head (3) with head plate (4) combining as a unit with an ear fishplate (5) overlapping the support profile. Its ears (6, 7) accommodate a clamp screw (12, 13) passing through this profile. A clamp fixed to the plate has an angular piece (16) with one shank (17) fixed to it for cap (1) or beam support, and the other (18) combining with the screw clamp (20) to embrace the cap or beam flange (19).</p> |
