3

ii) cam profile:

Different types of follower motions –

The follower during its travel may have one of the following motions:-

Uniform velocity, Simple harmonic motion, Uniform acceleration and retardation, Cycloidal motion.

Displacement Diagram of Uniform Velocity:

(1) Pitch circle- Circle drawn from centre of cam through pitch points.

(2) Pressure angle- Angle between direction of follower motion and normal to pitch curve.

(3) Stroke- Maximum travel of follower from its lowest position to top most position.

(4) Module –(Gears) – Ratio of pitch circle diameter in mm to No. of teeth on gear.

Advantages of roller follower over knife edge follower a) Roller follower has less wear and tear than knife edge follower. b) Power required for driving the cam is less due to less frictional force between cam and follower.

Limitations of knife edge follower are:

1. Excessive wear due to small area of contact between cam & follower surfaces.

2. In this follower a considerable thrust exists between the follower and guide.