Importance

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Abstract

A double cam drive operates on a main drive shaft of a buttonhole sewing machine is disclosed. Three double cams are arranged sequentially on the main drive shaft. A first double cam operates a looper mechanism, a second double cam drives a feeder, and a third double cam drives a needle bar mount for operating a bite mechanism to deflect a needle housing to make side stitches and tacks. Each double cam has a cam collar and two generally-circular concentric cams. Each cam of a double cam is positioned off-center on the cam collar with one cam positioned opposite the other. The three double cams have mounted collars at axial ends for securing the double cams to the shaft. Spacers are positioned between any two adjacent double cams for creating the proper spacing between the cams. A follower plate is pivoted on a stub shaft and has two rollers. The first roller contacts an outer surface of the first double cam and the second roller contacts an outside surface of the second double cam. The first roller is positioned directly opposite the second roller. The positioning of the cams on the cam collars and the positioning of the rollers allows the cams to remain in constant contact with a given drive mechanism.

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First Claim