公开(公告)号：US07222559B2

公开(公告)日：2007-05-29

申请号：US11204949

申请日：2005-08-16

Applicant: Chun Fu Wang

Inventor： Chun Fu Wang

IPC: B25B23/14 ,  B25B23/157 ,  B25B23/142 ,  B25B23/159

CPC classification number: B25B23/1427 ,  B25B15/00

Abstract: A screwdriver comprises a torque setting mechanism including a torque adjustment ring, an actuation rod threadedly secured to the upper torque adjustment ring and a lower torque adjustment nut, a spring biased sleeve with the actuation rod passed, and a clutch ring snugly put on two opposing intermediate flats of the actuation rod and having an upper surface engaged the torque adjustment ring and a lower surface formed with recesses engaged with steel balls on an upper surface of a support ring in the sleeve. Turning a rotatable handle will turn the sleeve. The clutch ring will disengage with the steel balls if the torque exceeds a set value. Thus, the torque exerted on the handle will not transmit to a shank secured to the actuation rod so as to prevent a screw from being over-driven by the shank.