Cam and follower mechanism types and functions

A cam is a mechanical member which impart desired motion to the follower by direct contact. Cam may be rotating or reciprocating while a follower may be rotating, reciprocating and oscillating. A cam-follower forms higher pair as they have point contact at the junction. From now we will term cam and follower mechanism as cam only for understanding.

Application of cam: IC engines, machine tools, and mechanism

 

Cam and follower mechanism

 

 

Elements of cam

• Driver member is cam
• The driven member is a follower
• A frame or structure which guides both cam and follower

 

Types of cam

 

According to shape

 

• Wedge or flat cam

This cam has transnational motion.

• Radial or disc cam

Here follower moves radically from the center of rotation of the cam.

• Spiral cam

This is also known as face cam as a groove is cut in the form of the spiral.

• Cylindrical cam

A circumferential contour is cut on the cylinder surface which rotates about its axis. It is also known as barrel or drum cam.

• Conjugate cam

This is double disc cam used when we require low wear, noise and better control of follower, high speed and high dynamic load.

• Globoidal cam

It has two types of faces- convex and concave. It is used for moderate speed and angle of oscillation of follower is large.

 

According to follower movement

• Rise-Return-Rise (RRR)
• Dwell-Rise-Return-Dwell (DRRDS)
• Dwell-Rise-Dwell-Return-Dwell (DRDRD)

 

 

Types of followers

 

According to shape

 

• Knife-edge follower

As the name implies, it has knife shape edge. It is more prone to wear t point of contact.

• Roller Follower

It consists a roller near the point of contact. It is preferred for low speed as at high-speed sliding occurs.

• Mushroom follower

Its edge shape is like a mushroom.

 

 

According to movement

 

• Reciprocating follower
• Oscillating follower

 

 

According to line of movement

 

• Radial follower : line of movement pass through center of rotation of cam.
• Offset follower: line of movement is offset from center of rotation of cam.