Attached to the revolving disk in this drive is a triangular cam, which is a projection on a rotating wheel for giving or receiving motion against its edge. In this case, the disk and cam give the motion. The rod is at rest at the completion of each stroke. This form of eccentric is used on a steam-engine in the Paris Mint.
[Virginia Downward & William M. Clark, 1930]

[Editor’s Note: Today this cam is called a Reuleaux Triangle, after Franz Reuleaux who wrote about curves of constant width and their kinematic application. This model can also be found in the Cornell Reuleaux models as L-1, L-2 as well as in B-2. This model is also called a positive return cam. It produces a dwell twice per cycle of the rotary input. FCM]

Francis Moon 2005-00-00