US Patent 6887018 Chuck for annular core bit

A chuck for an annular core bit (1) having an inner thread (2) includes a motor-driven rotatable spindle (4) having a threaded support (5) cooperating with the inner thread (2) for supporting the annular core bit (1), a stop member (7) associated with the axial stop flange (6) provided on the work spindle (4), locking wedge elements (9) for axially connecting the stop member (7) with the axial stop flange (6) under compressive strain, and a manually actuatable, displaceable release member (10) for displacing the locking wedge elements (9) between a position in which the locking wedge means (9) axially connects the stop member (7) and the axial stop flange (6) under compressive strain, and a position in which the stop member (7) is axially displaceable relative to the axial stop flange (6).