Handwheel clutch for sewing machines

Claim 1

In a sewing machine having an arm shaft, a handwheel, and a drive means for rotating said handwheel, a clutch means for drivingly coupling said handwheel to said arm shaft comprising a drive notch formed in said handwheel and a driving element supported on said arm shaft for rotation therewith and arranged to tilt between each of two bistable positions, a first of said bistable positions in which said driving element is in driving engagement with said drive notch and a second of said bistable positions in which said driving element is out of driving engagement with said drive notch, wherein said driving element comprises: a. a substantially planar yoke having a pair of flexible members each joined at one extremity to said yoke and arranged with their free extremities facing each other and spaced apart a predetermined distance; b. diametrically opposed reception seat surfaces formed on said arm shaft spaced apart a distance which is greater than said predetermined distance between said free extremities of said flexible members; c. said yoke being assembled on said arm shaft with said free extremities of said flexible members arranged each in engagement with a respective one of the diametrically opposed reception seat surfaces on said arm shaft and with said flexible members being flexed each to a position on an opposite side of the plane of said yoke; and d. means for interlocking said yoke with said arm shaft for rotation therewith when said free extremities of said flexible members are in engagement with said reception seat surfaces.