| 摘要 |
<p>1,188,913. Wells &c. RANNEY INTERNATIONAL S.A. 18 Oct., 1968 [23 Oct., 1967], No. 49536/68. Heading E1F. A digging head 12 for a water collection screen pipe 14 extending radially outwards from a well 17 has a nose portion with a cross-section constituted by a U-shaped base 52, 53 surmounted by a dome 46. The nose portion merges into an annular portion 62 welded to pipe 14 and having a Venturi portion 66 forming a seat for a pipe 31 used during boring to remove water and debris. Jacks are used to push the pipe 14 and head 12 outwardly.</p> |
