Technical Terms used in CAM

• Base circle: It is the smallest circle tangent to the cam profile (contour) drawn from the center of rotation of a radial cam.
• Trace point: It is the reference point on the follower to trace the cam profile such as the knife-edge follower and the center of the roller of a roller follower.
  Pitch curve: It is the curve drawn by the trace point assuming that the cam is fixed, and the trace point of the follower rotates around the cam.
• Pressure angle: It represents the steepness of the cam profile, it is the angle between the normal to the pitch curve at a point and the direction of follower motion. It varies in magnitude at all instants of follower motion.
• Pitch point: It is the point on the pitch curve at which pressure angle is maximum.
• Pitch circle: It is the circle passing through the pitch point and concentric with the base circle.
• Prime circle: The smallest circle drawn tangent to pitch curve is known as the prime circle.
• Angle of Ascent (outstroke): It is the angle turned by cam during the time of rise of follower.
• Angle of Dwell: It is the angle turned by cam while the follower remains stationary at the highest or lowest position.
• Angle of descent (Returnstroke): It is the angle turned by cam when follower returns to its initial position.
• Angle of action: It is the angle turned by cam during beginning of rise and the end of return of the follower.