Patent ID: 7896356

Claim:
A chuck provided on a transmission shaft driven by a power source, the chuck comprising: a chuck body having a longitudinal central axis and connected at its rear end to the transmission shaft to drive the chuck body to rotate about the central axis, wherein plural inclined holes are equally arranged in the chuck body; plural jaws provided in the inclined holes of the chuck body, wherein each of the jaws has male thread at its rear end and a gripping portion at its front end, and slides back and forth along the inclined hole through thread transmission so as to grip or release a tool handle; an outer sleeve rotatablely fitted around the chuck body; and a transmission nut fitted around the chuck body and indirectly connected to the outer sleeve, wherein the outer sleeve can be rotated to drive the transmission nut, on the inner surface of which female thread is formed which engages with the male thread of the jaws to drive the jaws; characterized in that the chuck further comprises: a drive pendulum support sleeve, located between the outer sleeve and the transmission nut, connected to the outer sleeve and fitted around the chuck body; a drive pendulum, provided on the drive pendulum support sleeve, swinging between a first position and a second position about a connection portion where the drive pendulum and the drive pendulum support sleeve are connected, and having a first drive portion and a second drive portion thereon, wherein the drive pendulum drives the transmission nut along a first transmission path through the first drive portion when it is in the first position while drives the transmission nut along a second transmission path through the second drive portion when it is in the second position with the second driving path providing greater gripping force than that of the first driving path.