| 摘要 |
A shank 11 on a tool bit for percussion drilling or chiseling has at least two rotary entrainment grooves (13, 14, 16), however, they are not arranged in diametrically opposed relation. In addition, the shank has at least one locking groove (12). The rotary entrainment grooves (13, 14, 16) are open at the end face (17) of the shank inserted into the chuck, so that rotary entrainment members in a tool bit chuck can be inserted into the rotary entrainment grooves (13, 14, 16). Locking groove (12) is closed at its end adjacent the end (17) of the tool bit inserted into the chuck, so that a locking member of the chuck can fit into the locking groove to prevent axial displacement of the tool bit out of the chuck. To reduce significantly the wear of the shank and the chuck, the shank has an additional rotary entrainment groove (15) located diametrically opposite the locking groove (12). Further, an additional rotary entrainment member is provided opposite the locking member in the chuck.
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