Patent Number: 6,305,481

Title: Clutch mechanism for use in a power-driven tool

Abstract: A lock washer (24) presses balls (21) and pins (23) against a clutch cam(18) with protrusions (19) formed on its front face. A rear end (25a) of aspring holder (25) abuts on the inner edge of the front face of the lockwasher (24) while the half of the front end surface of each pin (23) abutson the rear face of the outer edge of the lock washer (24). Furthermore,the compression spring (26) also abuts on the lock washer (24) with itsouter edge approximately aligned with the outer edge of the lock washer(24). Therefore, if a large load is instantaneously applied to a spindle(11) at the end of screw tightening, the outer edge of the lock washer(24) deforms forward. This in turn causes the balls (21) to ride over theprotrusions (19) of the clutch face, thus allowing a slight rotation ofthe internal gear (10c). This clutch operation lessens the impact thatoccurs at the end of screw tightening, serving to protect the toolmechanism and to reduce the shock to the operator's hand.

Inventors: Yamazaki; Takashi (Anjo, JP), Oda; Zenichi (Anjo, JP), Tozawa; Katsumi (Anjo, JP)


International Classification:

Expiration Date: 10/23/2013