| 摘要 |
A coring drill for earth and rock is provided with an annular outer drilling crown 6, 7 and with an inner drilling crown 8, 9 which can be drawn into the tubular drilling rod 1-3 and thus form a coring space 44. During drilling, flushing agent is supplied through the drilling crown 6-9. During coring, the inner drilling crown 8, 9 shuts off this flushing-agent supply. Instead, flushing agent flows out through openings 23 in the wall of the drilling rod in order to reduce the friction between the drilling rod and the surrounding earth or rock. <IMAGE> |
