Device for releasing drill stems screwed to one another

摘要

A breaking device for releasing drill stems, in particular augers (7'), screwed into one another to form a drill string comprises an externally threaded journal at its one front end and a corresponding recess at the opposite end with a matching internal thread for screwing in the next drill stem (7'). A drill head (5), which is likewise provided with a threaded connection (17), serves to drive the last-protruding drill stem (7') of the drill string. So that the drill stems screwed into one another extremely tightly can be easily and safely released again after the drilling operation without human exertion, provision is made for an extension surface (33) deviating in cross-section from a full circle to be provided on the rotatable drill head (5). In this arrangement, a rotary connection element (27) producing a positive-locking connection between the drill head (5) and the end area of the adjoining drill stem (7') and having two corresponding positive-locking recesses (35, 37) can be slipped with one of its sides onto the extension surface (33) on the drill head (5) and at least indirectly with its opposite sides onto the spanner surface (15) which is made on the end-face area of a drill stem (7') (Fig.). <IMAGE>