In case of knife edge follower there is sliding motion between the contacting surface of cam and follower. Because of small contact area, there is excessive wear; therefore it is not frequently used. Whereas in roller follower there is rolling motion between contacting surfacing and more contact area, therefore rate of wear is greatly reduced.
Advantages: i) Less wear, more life ii) Less side thrust as compared to knife edge follower.
Application: Used in stationary oil and gas engines
Motion of the Follower :
1. Uniform velocity, 2. Simple harmonic motion,
3. Uniform acceleration and retardation, and 4. Cycloidal motion.
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.