A good coupling should have the following requirements: (i) It should be easy to connect and disconnect. (ii) It should transmit the full power from one shaft to another shaft without losses. (iii) It should hold the shafts in perfect alignment. (iv) It should reduce the transmission of shock loads from one shaft to another shaft. (v) It should have no projecting parts
(i) Sunk key: Rectangular sunk key, Square sunk key and Parallel sunk key (ii) Gib-head key (iii) Feather key Any four (iv) Woodruff key types of keys (v) Saddle key: Flat saddle key, Hollow saddle key (vi) Tangent key (vii) Round key
Fig shows a displacement diagram and a cam profile for the roller follower.
Types of followers The followers may be classified as discussed below:
b) Types of cam: 1. Radial or disc cam 2. Cylindrical cam
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.
