Cam Terminology

Radius of Curvature,
Center of Curvature,
The roundness at any given point on a curve expressed as the radius of a circle with an equivalent curve. The center of the equivalent circle is the center of curvature, and the inverse of the radius of curvature is the curvature. NOTE: The curvature of a straight line is zero while the radius of curvature is infinite. In general use with cams, the radius of curvature ρ of the cam operating a roller follower refers to the center of the cam follower.
Radius of Cam
In a solid cam, the radius from the center of the surface of the cam is referred to as the representative radius of the cam so that depth fluctuations in pressure angle and radius of curvature fluctuations do not effect the evaluation of the characteristics of the cam.

Residual Vibration
The vibration that exists in followers when a follower in motion comes to a stop.

Rib Cam, Ribbed Cam
A cam that has ribs that are pinched by rollers for positive control without backlash.

Roller Center Path
The trajectory of the center of the roller as it is rotated around the center of the cam shaft with the cam held stationary.

Roller Follower
The round roller-like mechanism at the tip of the follower.

Roller Follower
An outer ring that houses needle rollers so that it can rotate. The outer ring directly rolls along the track of the cam.

Roller Gear Cam
A concave globoidal cam used to obtain intermittent indexing or oscillating motions. The tapered ribs and roller followers are in positive contact and preloaded for strong rigidity and no backlash. Suitable for high-speed driving applications.

Rotation Toward Pivot
Applies to oscillating followers when the roller is rotating in front of the pivot of the lever in respect to the rotation of the cam. See also rotation toward roller.

Rotation Toward Roller
Applies to oscillating followers when the cam is rotating from the pivot toward the roller.