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 a spring holder (25) abuts on the inner edge of the front face of the lock washer (24) while the half of the front end surface of each pin (23) abuts on 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 its outer 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 the protrusions (19) of the clutch face, thus allowing a slight rotation of the internal gear (10c). This clutch operation lessens the impact that occurs at the end of screw tightening, serving to protect the tool mechanism and to reduce the shock to the operator's hand.

Dependencies are inferred from the claim text.