What is Cam and Follower? – Classification

A cam and follower mechanism is a profiled shape mounted on a shaft that causes a lever or follower to move. Cams are used to convert rotary to linear (reciprocating) motion. As the cam rotates, the follower rises and falls in a process known as reciprocating motion.

What is Cam?

A cam is a rotating element that gives an oscillator or reciprocating motion to the follower which is another element of this machine by direct contact.

When the two links are connected either along a line or at a point, it is called a higher pair. Two such higher pair mechanisms will be included in a cam-follower system. A higher pair mechanism is known as cam and follower.

For the smooth functioning of a cam-follower mechanism, it is imperative that the follower should move smoothly without requiring too much input power, which means the follower should not jam, during its movement.

In an IC engine the valves have to be kept open; first, then close it and keep it closed, all these timing operations can be easily set by having cam-follower mechanisms. In the case of linkages, we study planar linkages or two- dimensional linkages, and more.

fig-1
Animation of cam and Follower Motion

Types of Cam

There are many types of cams describe below:

Types of Cam:

  • Disk or Plate cam.
  • Cylindrical cam.
  • Translating cam.
  • Wedge cam.
  • Spiral cam.
  • Heart-shaped cam.
  • Conjugate cam
  • Globoidal Cams
  • Spherical cam

1. Disk or Plate Cam

The disc (or plate) cam has an irregular contour to provide a specific motion to the follower. The follower rotates in a plane that moves on the axis of rotation of the camshaft and place in contact with the cam by springs or gravity.

figure 2

2. Wedge Cam

The wedge cam has an angled flat regular contour to impart a specific motion of the follower.

figure 3

3. Spiral Cam

The spiral cam consists of a semi-circular or a spiral that shapes the Grooved contour, the cam moves in a reciprocating motion and the follower moves perpendicular to the axis of the cam.

figure 4

4. Cylindrical Cam

The cylindrical cam has a groove cut along its cylindrical surface. The roller follows the groove, and the follower moves in a plane parallel to the axis of rotation of the cylinder.

Cylindrical Cam

5. Heart-shaped Cam

This type of cam looks like an asymmetric heart. It mainly used to return a shaft to hold the cam to a set position by its pressure from a roller.

figure 6

6. Translating Cam

The translating cam is a contoured or grooved plate sliding on a guiding surface(s). The follower may oscillate or reciprocate. The contour or the shape of the groove determined by the specified motion of the follower.

part of translating cam

7. Conjugate cam

In these type two discs connect to each other and the axes of discs are offset by the distance, to form a cam profile. The follower has surface contact with a cam profile by two rollers. As the cam rotates follower follow it.

Conjugate cam

8. Globoidal Cams

Globoidal cam is a shaft and has a concave or convex circumference. On which groove is made by machining and this groove use for giving movement to the follower. Globoidal cam use for oscillating followers about a fixed point.

Globoidal Cams

9. Spherical cam

Spherical cam is in the form of spherical shape on which groove is made. Follower has surface contact with this groove. As cam rotate follower oscillate about a fixed point.

Types of Cam according to follower movement

In these category types of cam is classified as per movement of follower. Movement of follower is depending upon cam profile for this; cams are also classified according to follower movement.

1) Dwell Rise Dwell Return Dwell cam

In this type, follower movement is considering. As per name follower movement done in a way that first dwell then rise again dwell then return and again dwell. This all process is done in one rotation (360 degree) of cam.

2) Dwell Rise Return Dwell cam

In this type, follower movement is considering. As per name follower movement done in a way that first dwells then rise then return and again dwell. This process is done in one rotation (360 degrees) of the cam.

3) Rise Return Rise cam

In this type, follower movement is considering. As per name follower movement is done in way that first rise then return. This all process is done in one rotation (360 degree) of cam.

4) Dwell Rise Dwell cam

In this type, follower movement is considering. As per name follower movement done in a way that first dwell then rise then again dwell. This process is done in one rotation (360 degrees) of the cam. And at 360 degrees it suddenly falls to its first position.

Types of Cam according to the constraint of the follower

For proper functioning of the cam and follower mechanism, it is important to keep the surface contact between the cam profile and the follower at all times of rotation and any motion. For this, spring force, gravitational force, or positive drive are used in the cam and follower mechanism. On this basis, cams are classified based on the type of follower and are as follows.

1) Preloaded spring cam:

In this type of cam, the spring force use. The compression spring is preload into followers in such a way that it maintains surface contact all time.

2) Positive drive cam:

In this type of cam, it does not require any external force. The follower is design in such a way that it does not require any external force.

What is a Follower?

A follower is a rotating or an oscillating element of a machine that follows the motion of a cam by direct contact.

A follower is a translating or oscillating mechanical member that follows the motion of the cam. It can touch the surface profile of the cam or can be spring-loaded. It can have uniform velocity or can have uniform acceleration motion. Complicated output motion can be achieved with the help of the follower motion.

Types of Follower

There are different type of surface contact between cam and follower and according to surface contact they are classified as follows:

  • Types of follower according to Shape
  • Types of follower according to Movement
  • Types of follower according to the line of movement

Types of follower according to Shape

1) Knife-edge Follower

This type of follower has a sharp area of contact with the cam. This is the simplest among all of the followers and these kinds of followers are not in use in the case of fast application, because of its sharp edge.

one kind of Knife-edge Follower

2) Roller Follower

This type of follower mainly uses in high-speed operation because it has a smooth contact with the surface. This type of follower has less wear and tear as compared to the other followers.

example of Roller Follower

3) Flat-faced Follower

This type of follower looks like a flat surface with an irregular cam. This type of cam is used when the space is limited and this follower can resist more side thrust. This follower can also be used in a precision application.

Flat-faced Follower example

4) Spherical Follower

This type of follower has a curved but regular follower as well as cam. This is a modification of a flat-faced follower.

one of Spherical Follower example

Types of follower according to Movement

In this category followers are classified by the relative motion and movement between cam and follower these are as follow.

1) Translatory motion type follower

In this type of follower, follower have translatory motion means cam is rotating and follower reciprocating between guide way. Example of this type follower is knife edge follower, roller follower, flat follower and spherical follower.

2) Oscillatory motion type follower

In this type of follower, follower has oscillating motion. Cam rotates and as per cam profile follower also move but follower is fixed at point about which follower is oscillate. This type of follower is called as oscillatory motion type follower.

Types of follower according to the line of movement

1) Radial Follower:

In this type of follower, the line of movement passes through the center of the camshaft. Mainly the movement of the follower is in line. The follower is in a reciprocating motion.

Note: – Diagram is same as knife-edge follower

2) Offset Follower:

In this type of follower, the movement of the axis of the follower is not colinear with the cam axis.

Offset Follower example

FAQs.

What is Cam And Follower?

A cam and follower mechanism is a profiled shape mounted on a shaft that causes a lever or follower to move. Cams are used to convert rotary to linear (reciprocating) motion. As the cam rotates, the follower rises and falls in a process known as reciprocating motion.

What is a Cam?

When the two links are connected either along a line or at a point, it is called a higher pair. Two such higher pair mechanisms will be included in a cam-follower system. A higher pair mechanism is known as cam and follower.

What is a Follower?

A follower is a rotating or an oscillating element of a machine that follows the motion of cam by direct contact.

What are Types of Cam?

Types of Cam:
1. Disk or Plate cam.
2. Cylindrical cam.
3. Translating cam.
4. Wedge cam.
5. Spiral cam.
6. Heart-shaped cam.

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