Module 4 : Drives and Mechanisms

Lecture 3 : Cams

2.   Classification of followers:  

Followers can be classified based on

 

2.1  Classification based on type of surface contact between cam and follower

Figure 4.3.5 shows the schematics of various types of followers used cam mechanisms.

Figure 4.3.5 Types of follower based on the surface in contact

2.1.1 Knife edge follower

The contacting end of the follower has a sharp knife edge. A sliding motion exists between the contacting cam and follower surfaces. It is rarely used in practice because the small area of contacting surface results in excessive wear.

2.1.2  Roller follower

It consists of a cylindrical roller which rolls on cam surface. Because of the rolling motion between the contacting surfaces, the rate of wear is reduced in comparison with Knife edge follower. The roller followers are extensively used where more space is available such as gas and oil engines.

2.1.3  Flat face follower

The follower face is perfectly flat. It experiences a side thrust due to the friction between contact surfaces of follower and cam.

2.1.4 Spherical face follower

The contacting end of the follower is of spherical shape which overcomes the drawback of side thrust as experiences by flat face follower.

 

2.2  Classification based on followers' motion

Figure 4.3.6 shows the types of cams based followers' motion.

Figure 4.3.6 Classification of follower based on motion

 

2.2.1 Oscillating follower

In this configuration, the rotary motion of the cam is converted into predetermined oscillatory motion of the follower as shown in Figure 4.3.6 a.


2.2.2  Translating follower

These are also called as reciprocating follower. The follower reciprocates in the ‘guide' as the cam rotates uniformly as shown in Figure 4.3.6 b.