Cams : Theory Of Machines

Cams :

A cam is rotating machine element which gives reciprocating or oscillating motion to another element know as follower .

The cams are widely used for operating the inlet and exhaust values of internal combustion engines , automobile attachment of machineries ,paper cutting machines , spinning and weaving textile machineries ,feed mechanism of automatic lathes etc.

Classification of Followers :

1. According to surface in contact :

(a) Knife edge follower 

(b) Roller Follower 

(c) Flat Faced or Mushroom Follower

(d) Spherical Faced Follower

2. According to the motion of follower :

(a) Reciprocating or Translating follower 

(b) Oscillating or rotating follower

3. According to path of motion of follower :

(a) Radial follower 

(b) Off - set follower

Classification of cams :

1. Radial or disc cam 

2. Cylinderical cam

Terms used in radial cams :

1. Base curcle 

2. Trace point 

3. Pressure angle

4. Pitch point

5. Pitch circle

6. Pitch curve

7. Prime circle

8. Liftor stroke

Motion of Follower :

1. Uniform velocity

2. Simple harmonic motion

3. Uniform acceleration and retardation 

4. Cycloidal motion

Displacement , velocity and acceleration diagrams for the can when the follower moves with the above mentioned motions