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.