ELLIPTICAL CURVE (DWELL-RISE-DWELL CAM)

This member of the trigonometric family is developed from projections of a semi-ellipse .The contour of the elliptical curve and its characteristics depend upon the assumed proportions of the major and minor axes. As the horizontal axis increases the cam becomes larger with the velocities of start and stop slower. In other words, the curve is flatter at the top and the bottom as the ratio of the horizontal axis to the vertical axis is made larger .If the horizontal axis of the ellipse is zero in length, the contour in the displacement is a straight-line curve. A ratio of 2:4 gives a small cam for a given pressure angle .Increasing the ratio further to 11:8 makes the curve approach a parabolic curve .At this ratio , a fair cam-follower performance can be expressed at moderate cam speeds. Further increase in the ratio is not practical, since velocity, acceleration, and cam size becomes prohibitive.