Classification Based on Follower Movement:

The cams may be classified depend on the motion of the follower. The magnitude & position of the dwell period might differ from one cam to other. Throughout dwell period follower does not move. It can be zero. It can be at one place or even more than that:

Rise-Return-Rise (R-R-R):

This cam contains alternate rise and return of follower having no dwell periods. The displacement-time diagram for follower motion is illustrated in Figure. With every full rotation of the cam follower in either increasing or returning.

Figure: Rise-Reutrn-Rise (R-R-R) Cam

Dwell-Rise-Return-Dwell (D-R-R-D):

In this kind of cam, there is dwell period before begin of rise. The return follows instantly after rise & after return there is dwell period before rise commences. The displacement-time diagram for these kinds of cam is illustrated in Figure.

Figure: Dwell-Rise-Return-Dwell (D-R-R-D) Cam

Dwell-Rise-Dwell-Return-Dwell (D-R-D-R-D):

In this kind of cam rise begins after dwell. After rise there is once more dwell period after which return commences. In one total rotation of cam there are two dwell periods as illustrated in Figure. This kind of cams contains wide applications.

Figure: Dwell-Rise-Dwell-Return-Dwell (D-R-D-R-D) Cam