| 摘要 |
Means are provided to drill generally horizontal bores through heterogeneous fill and hard strata. A carriage providing power means to rotate a spindle is mounted on a generally horizontal track and is adapted to move longitudinally along the track. Swivel means about the spindle are provided with means to introduce a combined gas and liquid stream, suitably air and water, into a drill pipe connected to the spindle and through an impact drill mounted at the end of the drill pipe to power the drill and to flush cuttings from the hole.
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