According to manner of constraint of follower: -

To reproduce exactly the motion transmitted by cam to follower, it is necessary that two remain in touch at all speeds at all times.

This type of cam is of three types: -

1. Pre-loaded spring cam: - In this a pre loaded compression spring is used to maintain the contact between cam and the follower. Example: -wedge and flat cam

2. Positive drive cam:- In this type constant touch between cam and follower is maintained by a roller follower operating in the groove of a cam. Example: - spiral and spherical cam.

3. Gravity cam: - In this the rise of the cam is achieved by the rising surface of the cam and the return by the force of gravity or due to weight of cam. Example: -Flat cam