Patent ID: 7246801

Claim:
A self-tightening keyless chuck for gripping a tool shank, comprising: a rear sleeve ( 1 ); a body ( 2 ); a bearing ring ( 3 ); a bearing assembly ( 4 ); a nut ( 5 ); a jaw ( 6 ); a front sleeve ( 7 ); and a stopper ( 8 ), wherein a surface of at least one of the bearing ring ( 3 ) and the nut ( 5 ) that faces the bearing assembly ( 4 ) is provided with a recessed circumferential arcuate race ( 9 ), and a plurality of ball-shape grooves ( 10 ) are uniformly formed in an arcuate bottom surface of the arcuate race ( 9 ), and wherein the front sleeve ( 7 ) engages with the nut ( 5 ) through radial smooth press-fit.