Cam and Follower: Definition, Types, Working Principle, and Applications [PDF]

Introduction

In mechanical engineering, engineers often use a higher pair links mechanism that is renowned as Cam and Follower Mechanism. This pair of higher links are used to move links spontaneously or periodically. Cam and follower mechanisms are also used by engineers for ensuring zero or minimum degree of error. Cam was found in the 4th century in Al-jazari design. The Cam and Follower Mechanism is mostly used in the IC engines for driving the valves. Apart from that, the mechanism is often used by engineers as a part of the IC engine’s timing system.

Moreover, in the automotive industry Cam and Follower mechanism is used to drive fuel pumps. Furthermore, when multiple cams are incorporated within a single shaft it is called a camshaft. The mechanism is developed by incorporating three members they are, a driver member named Cam, a frame that supports cam and follower, the follower is guided by the frame and lastly, the driven member named as a follower.

What is Cam?

A cam is a rotating element that gives oscillating or reciprocating motion to the follower which is another element of this machine by direct contact. This part is mainly used to transform the motion from rotary into linear. It is a part of a machine which can be a rotating wheel (an electric wheel) or a shaft that strikes a lever’s various points at its circular path. In a steam hammer, an engineer can use a cam as a simple tooth to deliver pulses of the power to a Steam Hammer.

Types of Cam

There are various types of cams available, some of them are listed below:

• Disk or Plate cam
• Cylindrical cam
• Translating cam
• Wedge cam
• Spiral cam
• Heart-shaped cam

Disk or Plate Cam

A disk or plate cam is a mechanical component used in various machines to convert rotational motion into linear motion. It is essentially a circular plate with an off-center groove cut into its surface, which is connected to a sliding follower. As the cam rotates, the follower moves in and out of the groove, causing linear motion in a connected component.

This type of cam is commonly used in internal combustion engines to operate valves and in manufacturing equipment to control the movement of cutting tools. The design of the cam and follower mechanism is crucial to ensure smooth and accurate movement. The disk or plate cam is an essential component in many machines and plays a critical role in their overall operation and performance.

Cylindrical Cam

A cylindrical cam is a mechanical component used in machinery to convert rotary motion into linear motion or vice versa. It is a type of cam in which the cam surface is a cylinder. The cylindrical cam consists of two main components – the base and the follower. The base is the cylindrical surface with the cam profile cut into it, and the follower is a component that follows the motion of the base. As the cam rotates, the follower moves along the surface of the cam, resulting in linear motion.

Cylindrical cams are commonly used in engines, textile machinery, and other industrial equipment. They are designed to withstand high loads and operate smoothly for extended periods, making them an essential component in many industrial applications.

Translating Cam

This mechanism involves the use of a cam, which is a rotating component that has an irregular shape, and a follower, which is a component that moves along the surface of the cam. The translating cam works by converting the rotational motion of the cam into linear motion of the follower. This movement can be used to perform various functions such as opening or closing valves, controlling timing, and moving components.

The translating cam mechanism is widely used in automotive engines as it provides precise control over the opening and closing of valves, which is essential for the proper functioning of the engine.

Wedge Cam

The wedge cam is a type of cam and follower mechanism that is widely used in various mechanical applications. It consists of a wedge-shaped component that rotates about an axis, pushing against a follower to create motion in a linear or rotary direction. The cam and follower mechanism is commonly used in engines, machines, and other devices to convert rotational motion into linear or reciprocating motion.

The wedge cam is particularly useful in applications where high forces and loads are involved, as it provides a strong and stable mechanism for transmitting power. Overall, the wedge cam is a versatile and efficient component that plays an important role in many mechanical systems.

Spiral Cam

The spiral cam is a type of cam and follower mechanism that has gained significant popularity in various industries. It is widely used in machines that require smooth and precise motion control. The spiral cam is designed to convert rotary motion into linear motion with a high degree of accuracy. The cam has a spiral shape that allows the follower to move at a constant speed while following the cam’s contour.

One of the primary advantages of the spiral cam is its ability to provide smooth and consistent motion. Unlike other types of cams, the spiral cam does not produce sudden jerks or stops, which can damage the machine or component being operated. Additionally, the spiral cam’s design allows for higher speeds and greater accuracy, making it an ideal choice for applications that require high precision.

Heart-shaped Cam

A heart shaped cam is a type of cam that is widely used in machines, especially those that require linear motion. The unique shape of the cam ensures that the follower moves smoothly and precisely, without any jerks or sudden movements.

The heart shaped cam is commonly used in applications such as pumps, engines, and conveyor systems. It is also used in machines that require precise control over the movement of parts.

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. If a cam moves in reciprocating motion the follower moves vertically with respect to the axis of the cam. This part of the machine is mainly following the cam which can be in reciprocating or oscillating motion. It converts the rotary motion of cam into reciprocating or oscillating motion.

Types of Follower

There are various types of follower which some of which are as follows:

• Knife edge follower
• Roller follower
• Flat-faced follower
• Spherical follower
• Radial follower
• Offset Follower

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.

Roller Follower

This type of follower is mainly used 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.

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.

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.

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.

Offset Follower

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

Working Principle of Cam and Follower

The working principle of Cam and Follower depends on the mechanism of the combination of both Cam and Follower. Let us discuss each in detail.

Cam Mechanism

Cam is a mechanical component which is a rotating circle or eclipse about the minor axis of the Follower. Hence it can be explained easily that Cam is a mechanical component that transmits reciprocating, oscillating or linear motion to Follower. Cam’s shape is usually an oval or an imperfect circle or an eclipse.

If an engineer considers an oval-shaped Cam then he or she can see the movements which will form the outer burgee, which is periodic to its locus. This outer burgee is very useful and effective for works which are periodic mechanical. There are two types of Head Cams. First is Single Head Cam and the second is Multiple Head Cam. Cam is Rotating about minor axis or respect to Follower.

Follower Mechanism

A follower is a mechanical component concerning that the Cam rotates in an oscillatory or circular motion. Follower inhibits the push and pulls of the Cam. A follower is used to transfer the motion to the required machine part.

The Follower rotates in an oscillating or circular arc. The mechanism for Cam and the mechanism for Follower depend upon each other. The mechanism of Cam and Follower is essential in the engineering field and has many different functions to the different machines.

The Terminology of a Cam

Cam Profile

It is the surface area of a cam where follower touches.

Base Circle

It is the smallest circle of a cam profile drawn from the center of rotation of the cam.

Trace Point

By this point, we can trace the cam profile.

Pitch Curve

This curve is generated if we assume the cam is fixed and the trace point of the follower moves around the cam.

Pressure Angle

It is the angle measured normal to the pitch curve and line of motion of the follower.

Pitch Point

At this point the pressure angle is maximum.

Pitch Circle

It is the circle which passes through the pitch point.

Prime Circle

This is a circle that is drawn tangentially to the pitch curve and concentric to the base circle.

Applications of Cam and Follower

There are many different applications of Cam and Follower mechanism. Some of them are as follows:

• Internal Combustion Engine to close and open the outlet valve and intake valve.
• Automated Types of machinery, Cam and Follower are used in different parts which are automated in motion.
• In Hydraulic Systems, the main mechanism is Cam and Follower mechanism.
• In that case, the mechanism is dependent on the fluid pressure.
• In Printing Machinery, the mechanism of Cam and Follower helps the screen to be printed. The push helps to take the position where the printing will be done and the pull helps to print on that.
• In Textile Types of machinery, the mechanism of Cam and Follower helps to stitch clothes by a push and pull to move the Maku.
• Screw pieces of machinery.
• Gear-Cutting Machineries.
• Wall-Clock.
• Automatic Lathe Machine.

Importance of Cam and Follower

In the field of mechanical engineering, the Cam-follower mechanism plays a significant role in achieving even distribution of forces in a single machine component. By attaching a cylindrical roller in a machine component spontaneous movement can be achieved by an engineer. Cam follower can be used in a machine component regardless of the shape and size of the nut. Apart from that, varieties of linear motions can be found by utilizing the mechanism. Moreover, due to higher thickness as compared to other bearings Cam follower mechanism can absorb a higher amount of shock that increases the mechanical efficiency of a machine component.

Furthermore, the mechanism is entirely versatile that it can be used in a soda machine or also in an aircraft application. Besides, the mechanism is also used in the conveyor belt. In the case of engines, bearing the load of a camshaft can easily be devised by utilizing the fundamental approach of a crankshaft bearing. Although, flat followers are used by engineers to operate the valves of an engine whereas roller followers are used by engineers in oil and stationary engines. This type of preference occurred due to more availability of space of roller followers.

A video on Simple Cam & Follower Mechanism

FAQ’s

Conclusion

Cam follower mechanism plays a significant role as it utilized to drive a minute machine component seamlessly. Central locks and ordinary lock systems are also developed by incorporating the mechanism of cam and follower. Various terminologies are integrated with the mechanism that has to be understood by the user of the mechanism. Some of the terminologies are trace point, pitch curve, pressure angle and so on.

Cam and follower mechanisms are not a small part of mechanical engineering. Therefore, precision and patience are required to implement the mechanism in practice. At first, the user should be aware of the links and pairs before understanding the concept of cam and follower.

Cam is a higher pair device thus, the user should grant the degree of freedom to apply the same in a machine component. Lastly, it can be recommended that the pressure angle should not be increased by the user to restrict the potential impact of side thrust.

Media Credits

• Cam Animation by: Public Domain
• Video by: Sagar Patel