| 摘要 |
<p>An upright drilling wormgear unit (13) is movable up and down along an upright guiding unit (11,12), and a continuously moving screw blade is located on a shaft in a machine for drilling into the soil. The wormgear is coaxially surrounded by a sheathing tube (14), moving with it. Drive (15) turns them opposite ways round a common axis, and is operatively connected to their top ends. There may be an additional, downward-directed screw blade, above the first, with a spiral running the other way. This can drill holes of wide dia., without itself being strengthened or enlarged, and with no danger of walling collapse during drilling.</p> |
