epicycloidal wheel

plural epicycloidal wheels

1. A device for producing straight-line motion from circular motion, on the principle that a pin fastened in the periphery of a gear wheel will describe a straight line when the wheel rolls around inside a fixed internal gear of twice its diameter.

   1 more example

   The racks gear directly in the A-wheels, and the figures are placed on cylinders as in the Brunsviga. The carrying is done continuously by a train of epicycloidal wheels. The working is thus rendered very smooth, without the jerks which the ordinary carrying tooth produces; but the arrangement has the disadvantage that the resulting figures do not appear in a straight line

   1911, “Calculating Machines”, in Encyclopædia Britannica, 11th edition, New York, N.Y.: Encyclopædia Britannica, Inc.