| 摘要 |
<p>The portal-type scraper discharges material from stockpiles, with scraper booms derricking at points near the portal base on opposite sides, the sum of their lengths being roughly equal to the pile base width. One scraper is an auxiliary one, delivering the material into the working area of the other, and the auxiliary scraper is attached to an intermediate member, coupling it to the portal over a restrictor wall for the side of the pile. The member is a swing arm fixed to the scraper, and its pivot end is supported on the portal at a point clear of the outside of the wall. It has a recess in the underside fitting over the wall when the scraper iss lowered.</p> |
