HomeMechanical EngineeringCams and Followers: How they Work? Types, Nomenclature

Cams and Followers: How they Work? Types, Nomenclature [Diagrams & PDF]

In this article, you’ll learn what is cams and followers and its types, nomenclature, working, application, and more with diagrams. Also, you can download the free PDF file of this article at the end of it.

Cams and Followers

Cam and follower are a pair of higher links that are used to move links directly or periodically. It is used to decrease the degree of error. In the third century, the device known as the cam was produced by Hellenistic water-powered automata.

In addition, the device was found in al-Jazari design in the 4th century. Cams and followers’ mechanisms are mostly used in the internal combustion engine to operate the valves.

Also, the mechanism is often used by engineers as a part of the I.C.Es timing system. Although, the cam-follower mechanism is employed in the automotive industry to operate fuel pumps.

This mechanism is formed by combining three members, a driving member called the cam, a frame that holds the cam and the follower, the follower is controlled by the frame and, finally, the driven member is designated as the follower.

What is Cam?

The cam is a rotating part that provides reciprocating or oscillating motion to the follower by direct contact. This part is essentially used to change the movement from the rotary to linear.

It is a part of a machine, that is a revolving electric wheel or a shaft that hits a lever at several points on its circular path. It is widely used in a steam hammer as a simple tooth to transform pulses of the power to steam hammer.

Types of Cams

Following are the types of cams, which are explained below:

  1. According to the shape of the cam
    1. Wedge or flat cam
    2. Disk or Plate cam
    3. Spiral cam
    4. Cylindrical cam
    5. Heart-shaped cam
    6. Translating cam
    7. Snail drop cam
    8. Conjugate cam
    9. Globoidal cam
    10. Spherical cam
  2. According to the follower movement of the cam
    1. Rise return rise
    2. Dwell rise dwell return dwell
    3. Dwell rise return dwell
  3. According to the manner of the constraint of the follower
    1. Preloaded spring cam
    2. Gravity cam
    3. Positive drive cam

1. Wedge or Flat Cam

Cams and followers: Wedge or Flat Cam

The wedge or flat cam has a straight shape to provide a specific movement of the followers.

2. Disc or Plate Cam

Cams and followers: Disc or Plate Cam

The disk or plate cam does not have a straight shape to give a specific movement to the follower.

3. Spiral Cam

In spiral cam, it consists of a semi-circular or a spiral shape groove contour, the cam travels in a reciprocating movement and the follower moves perpendicular to the axis of the cam.

4. Cylindrical Cam

Cams and followers: Cylindrical Cam

In cylindrical cam, it consists of a groove in a cylindrical surface and the follower moves on a cylindrical surface parallel to the axis of the cylinder.

5. Heart-shaped Cam

Cams and followers: Heart-shaped Cam

The heart-shaped cam seems like an asymmetric heart. It is essentially used to turn a shaft to keep the cam in a defined position by its pressure from a roller.

6. Translating Cam

Translating Cam

The translating cam consists of a groove or contour plate and its follower oscillates in front of the plate. The groove or contour plate specifies the movement of the follower.

7. Snail Drop Cam

Cams and followers: Snail Drop Cam

The snail drop cam is used for example in a mechanical timekeeping clocking-in clock so that the daytime advance system could run at exactly midnight and involve a follower for more than 24 hours by the cam in a spiral path.

Which ended with a sharp cut-off. The follower will drop down and activate the day advance.

8. Conjugate Cam

Cams and followers: Conjugate Cam

The conjugated cam has a mechanism with two separate oscillating rollers. The followers as a conjugation measuring fixture. When the cam revolves, the change of the suboptimal angle between the two follower arms may indicate the variation of the cam profile errors.

9. Globoidal Cam

Globoidal Cam

In shape terminology, the globoidal cam is one of the most complex cams. The working surfaces of the globoidal cams are the contacting surfaces with the roller surfaces.

10. Spherical Cam

Cams and followers: Spherical Cam

The spherical cam mechanisms are an alternative to bevel gears, as they provide less back-lash and fewer friction losses.

What is Followers?

The follower is a rotating or oscillating element of a machine that follows the movement of the cam by direct contact. When a cam travels in reciprocating movement, the follower moves parallel on the cam axis.

It is a part of the machine, that is principally following a cam that can reciprocate or oscillate in movement. This converts the rotary movement of the cam into reciprocating or oscillating motion.

Types of Followers

Following are the types of followers, which are described below,

  1. According to the shape of the follower
    1. Roller follower
    2. Knife edge follower
    3. Flat-faced follower
    4. Spherical follower
  2. According to the movement of the follower
    1. Reciprocating follower
    2. Oscillating follower
  3. According to the line of movement of the follower
    1. Radial follower
    2. Offset Follower

1. Roller Follower

Roller Follower

The roller follower is essentially used in high-speed operations because it holds a smooth contact with the surface. It has less wear and tear than the other followers.

2. Knife Edge Follower

Knife Edge Follower

In these types of followers, It is consists of a sharp area of ​​contact with the cam. It is the simplest among all followers and as such followers are not employed in case of fast application, as it has a sharp edge.

3. Flat-faced Follower

Flat-faced Follower

The flat-faced follower seems like a flat surface with an irregular cam. In this, the cam is utilized when space is limited and this follower can hold more thrust. This follower can also be applied in a specific application.

4. Spherical Follower

Spherical Follower

The spherical follower consists of a curved or regular follower as well as a cam. This is a modification of a flat-faced follower.

5. Reciprocating Follower

In this type of follower, as the cam rotates, the follower reciprocates or changes into the guide.

6. Oscillating Follower

The oscillating follower is placed at a proper point on the frame and oscillates thus the cam causes the rotary motion.

7. Radial Follower

The radial follower is used when the line of movement of the follower passes through the centre of rotation of the camshaft. It is in a reciprocating motion.

8. Offset Follower

Offset Follower

The offset follower is used when the line of motion of the follower is offset from the centre of rotation of the camshaft.

How Does Cams and Followers Works?

Working of Cam

The cam is a mechanical element that is a revolving wheel about the short axis of the follower. Or in simple words, the cam is a mechanical element that reciprocates, oscillates or linear motion to the follower.

The shape of the cam is usually an oval or incomplete circle or eclipse. If an engineer considers an oval-shaped cam, he or she can observe movements that will create an external load, which is periodic for its location.

This external burial is very useful and effective for tasks that are periodic mechanical. The single and multiple head cams are the two types of the head cam.

Working of Follower

A follower is a mechanical element with respect to which the cam rotates in an oscillating or circular motion. The follower prevents the push and pulls of the cam. The followers are used to transfer the movement to the required machine part.

The mechanism for the cams and followers depends on each other. The follower revolves in an oscillating or circular arc.

The cam and follower mechanism is necessary for the engineering field and it has many different functions for different machines.

Nomenclature or Terminology of Cam

Nomenclature or Terminology of Cam

Following are the terms used in terminology of cam:

  1. Cam profile
  2. Base circle
  3. Pitch curve
  4. Trace point
  5. Pressure angle
  6. Pitch point
  7. Pitch circle
  8. Prime circle

1. Cam Profile

Cam profile is the surface area of a cam where follower meets.

2. Base Circle

This is the smallest circle of the cam profile formed from the centre rotation of the cam.

3. Pitch Curve

Pitch curve is created when we assume that the cam is fine and the tracepoint of the follower rotates around the cam.

4. Trace Point

With the help of trace point, we can detect the cam profile.

5. Pressure Angle

Pressure angle is created between the normal to pitch curve and line of motion of the follower.

6. Pitch Point

The pitch point is a point, where the pressure angle is maximum.

7. Pitch Circle

The pitch circle passes through the pitch point.

8. Prime Circle

Prime circle is a circle, which is drawn from the tangent to the pitch curve and concentric to the base circle.

Why Need Cams and Followers?

In the department of mechanical engineering, the cams and followers mechanism represents an important role in achieving uniform distribution of forces in a single machine element.

Spontaneous movement can be achieved by an engineer by attaching a cylindrical roller to a machine element. The Cam and followers can be used in machine elements with the size and shape of the nut. In addition, varieties of linear motions can be found using this mechanism.

Apart from that, the cam and follower mechanism can absorb a high amount of shock due to the greater thickness compared to other bearings which increase the mechanical efficiency of the machine element.

Also, this mechanism is completely versatile in that it can be applied in a soda machine or in aircraft applications. Furthermore, It is also used in conveyor belts.

However, flat followers are commonly used to operate the valves of an engine while roller followers are used in oil and stationary engines.

Where Cams and Followers Used?

Following are the applications of cams and followers:

  1. Cam and follower are used in the i.c engine to close and open the outlet valve and intake valve.
  2. It is also used as a hydraulic system. Because the mechanism is dependent on the fluid pressure.
  3. Cam and follower are employed in printing machinery for printing the screen. Push helps take the position where printing will be done and the pull helps to print on it.
  4. This mechanism is also useful in textile machines for sewing and pulling the fabric with one push to run the make.
  5. Used in screw pieces of machinery and Gear-Cutting types of machinery.
  6. Cam and follower also applied in wall-clock and automatic lathe machine.

Conclusion

Cams and followers have a wide range of applications in manufacturing industries. I have covered all the types of cams and followers with diagrams but still, if you have any questions about cams and followers then you can ask me in the comments.

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That’s it thanks for reading.

Saif M
Saif M. is a Mechanical Engineer by profession. He completed his engineering studies in 2014 and is currently working in a large firm as Mechanical Engineer. He is also an author and editor at theengineerspost.com