1. What is Cams and Followers ?
A cam is a rotating or sliding element with a specially shaped profile, while a follower is a component that remains in contact with the cam surface and moves according to its contour. As the cam rotates, the follower executes a specific motion (linear or angular).
a cams and followers mechanism is a higher-pair system used to transform rotary motion into a specific, predetermined reciprocating or oscillating motion. This mechanism is essential in automated machinery, internal combustion engines, and precision timing systems.
The motion generated is not simple harmonic by default—it depends entirely on the cam profile.They are used to convert rotary motion into oscillatory motion or oscillatory motion into rotary motion.Necessary elements of a cam mechanism are:
- A frame which supports the cam and guides the follower
- A driver member known as the cam
- A driven member called the follower
Table of Contents
2. Elements of a Cam Mechanism
- Cam: The driving member, usually a rotating wheel or shaft with a specific profile (shape).
- Follower: The driven member that stays in contact with the cam profile and moves according to its shape.
- Frame: The support structure that guides the follower’s path.
- Spring: Often used to ensure the follower maintains constant contact with the cam, especially at high speed.
3. Types of Cams
1. Disc (Radial) Cam
The follower moves in a direction perpendicular to the cam’s axis of rotation. These are the most common cams found in IC engine valve trains.
2. Cylindrical Cam
- Has a groove cut on a cylindrical surface
- Produces complex follower motion
3. Translating Cam
- Cam moves linearly instead of rotating
4. Types of Followers
Based on Motion:
- Translating follower – moves in a straight line
- Oscillating follower – rotates about a pivot
Based on Contact Surface:
- Knife-edge follower – simple but high wear
- Roller follower – reduced friction and wear
- Flat-faced follower – better load distribution
| Type | Description | Best For… |
| Knife-Edge | A sharp point touches the cam. | High precision but wears down very quickly. |
| Roller | Features a small roller at the contact point. | High-speed applications; reduces friction and wear. |
| Flat-Faced | A flat surface contacts the cam. | Used when space is limited; can handle high side-thrust. |
| Spherical | A curved surface similar to a flat-faced but rounded. | Reduces surface stress compared to flat followers. |
5. Follower Motion Types
The motion of the follower is defined during cam design:
- Uniform velocity motion
- Simple harmonic motion (SHM)
- Uniform acceleration and retardation
- Cycloidal motion (preferred for smooth operation)
These motions are analyzed using concepts from Kinematics.
6. Important Terminology
- Base Circle – The smallest circle tangent to the cam profile. The size of the cam is determined by this.
- Prime Circle – Circle passing through pitch point
- Pitch Curve – Path traced by follower point
- Lift (Stroke) – Maximum displacement of follower
- Dwell – Period when follower remains stationary
7. Design Considerations
- Avoid excessive wear and friction
- Ensure continuous contact between cam and follower
- Minimize vibration and noise
- Optimize pressure angle for smooth motion
- Proper material selection and lubrication
8. Cams and followers Advantages and Dis-advantages
| Advantages | Disadvantages |
|---|---|
- Produces complex and precise motion
- Compact and simple mechanism
- Suitable for high-speed operations
9. Disadvantages
- High contact stresses
- Wear due to sliding motion
- Requires accurate manufacturing
10. Applications
- Internal combustion engines – valve timing mechanism
- Printing machines
- Textile machinery
- Automatic packaging machines
- Robotics and automation systems