A jaw for use in a drill chuck having a longitudinal center axis, comprising a chuck body which includes a jaw face formed on an inner surface of the chuck body and a plurality of teeth formed on an outer surface of the chuck body, the jaw face being substantially parallel to the longitudinal center axis. A ridge depends inwardly from the jaw face toward the longitudinal center axis. The ridge includes a tool engaging surface that is substantially parallel to the longitudinal center axis and has a width of between 0.020 to 0.060 inches.

A chuck assembly, for use with a rotary power tool, includes a chuck body rotatable about an axis, a plurality of jaws supported by the chuck body for relative movement therewith between a retracted position for permitting insertion of a tool bit within the chuck body and an extended position for clamping the tool bit, a plurality of clamping nuts surrounding the chuck body and having interior threads engageable with corresponding threads on the respective jaws, a tightening sleeve surrounding and threadably engaged with the chuck body for relative rotation therewith, and a wedge defined on the tightening sleeve for selective engagement with the clamping nuts for inwardly displacing the clamping nuts, causing the respective threads on the clamping nuts and jaws to engage, in response to rotation of the tightening sleeve relative to the chuck body in a tightening direction.

A fastener driving tool includes a shaft with a working region disposed at a first end of the shaft and configured to drive a fastener, a shank portion disposed proximate a second end of the shaft and configured to couple the shaft to a power tool, and a reduced diameter torsion zone disposed between the shank portion and the working region, the torsion zone extending from a first shoulder closer to the working region to a second shoulder closer to the shank portion. A length (L) and a radius (c) of the torsion zone have been optimized so that approximately half of breakages occur in the working region and approximately half of breakages occur in the torsion zone.

A chuck device in which a rotary sleeve provided to a main body is rotated, and by rotation of an annular rotary body which rotates together with the rotary sleeve, jaws screwed together with the rotary body are expanded, contracted, advanced, and retracted, and a tool is gripped by the jaws; the chuck device comprising a retaining engaging body for engaging with the rotary body and preventing the rotary sleeve from coming out of the rotary body; wherein the retaining engaging body is provided to be fixed to a proximal end side of the rotary sleeve; a rotation transmission part for directly or indirectly transmitting the rotation of the rotary sleeve to the rotary body is provided to the retaining engaging body; and the rotation of the rotary sleeve is transmitted to the rotary body via the retaining engaging body, and the rotary body rotates together with the rotary sleeve.

Disclosed are a clutch device, a drill chuck, a power tool, and a bidirectional rotation method of the drill chuck. The clutch device comprises a return elastic member, a transmission assembly and a rotating portion, wherein the transmission assembly comprises at least two oppositely arranged engagement portions; the engagement between the two engagement portions enables a front body and a rear body to rotate synchronously; the rotation of the rotating portion in a first direction enables the return elastic member to be compressed, such that the two engagement portions are disconnected; and the rotation of the rotating portion in a second direction enables the compressed return elastic member to return to an initial position such that the two engagement portions are engaged. The drill chuck comprises a front body, a rear body, clamping jaws and the clutch device; and the power tool comprises a driving shaft and the drill chuck.