Importance

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Abstract

A stop cam is positioned on the main drive shaft of the buttonhole sewing machine. A stop lever moves axially between an engaged and a disengaged position. A heavy compression spring absorbs machine kinetic energy when the stop lever is in contact with the stop cam. A slide bar is positioned on one side of a lower end of the stop lever to hold the stop lever away from the stop cam. A spring positioned on the stop lever, opposite the slide bar, moves the stop lever into alignment with the stop cam. The tripping of a pedal moves the slide bar away from the stop lever thereby allowing the spring to move the stop lever into an engaged position. After substantial slowing, reaching the maximum displacement and spring loading, the cam presents a low flat surface to the stop lever. The spring pulls the lever against the flat and any remaining kinetic energy is too little for the cam to continue turning and raise the stop lever. The asymmetrical shape of the stop cam and the shape of the stop lever allows the sewing machine to come to rest in a predefined needle-up position. The stop bolt and spring housing are adjustable to provide exact stopping force and position.

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First Claim