Patent ID: 7261169

Claim:
A shank for a working tool which is at least one of rotatable about a tool axis (A) and percussively displaceable therealong, the shank having, at least partially along the tool axis (A), a radial reference dimension (R) and comprising a lockable region ( 3 ); at least three recesses ( 5 ) provided within the lockable region ( 3 ) and arranged in a cross-section (II-II) to the tool axis (A) at least at angles of 0°, 120°, and 240° within the radial reference dimension (R), with at least one of the recesses ( 5 ) being axially closed toward a free end of the shank ( 1 ); and at least one protrusion ( 6 ) arranged circumferentially between two adjacent recesses ( 5 ) and outside of the radial reference dimension (R), wherein a sum of central recess angles (α) of the recesses ( 5 ) arranged within the radial reference dimension (R) in a cross-section (lI-II) amounts to at least 150°, and a sum of central protrusion angles (β) of the at least one protrusion ( 6 ) is less than 150°, and a difference between the sum of the central recess angles (α) and the sum of the central protrusion angles (β) amounts to at least 15°; and wherein an axially extending guide surface ( 4 c ) is provided in a circumferential region between a recess ( 5 ) and a projection ( 6 ) in the lockable region ( 3 ).