| 摘要 |
The device comprises a set of rods comprising a number of rods (6) which are journalled in a surrounding set of tubes (7) by means of elastic bushings (52,53). One of the bushings is provided with a lip (54) which sealingly rests against the rod (6) when flushing medium is not supplied to the space between the set of rods and the set of tubes but allows passage of flushing medium at drilling. |
