A Swiss disco group. Their greatest hit was Intermittent Motion. No, wait, that's not right...Also known as a Geneva gear. A drive gear used in motion picture projectors to translate the continuous motion of the motor, (and bulk of the film transport), into intermittent motion needed to display the film frame by frame, (at the film gate). This is accomplished with a cross shaped gear with deep radial slots cut into it at 90º intervals. The gear is positioned over the circumference of a drive disk in such a way that a peg on the drive disk enters a slot and drives the gear 90º, and then exits the same slot. The drive disk then travels through 270º, before engaging the next slot in the gear. There are 4 turns of the drive disk to each turn of the gear, and the gear remains stationary (dwell) ¾ of the time. This arrangement would also work with a gear with groves at 120º intervals, (yielding a dwell ratio of 2/3), but I have never seen this arrangement in practice.

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