In mechanical engineering, a higher pair links mechanism is known as a cam and follower mechanism. The cam and follower are machined types of roller or needle bearings designed to work on each other. They come in a vast array of various configurations and they work depending on their applications and final output.
Cam and cam follower mechanisms are often used in mechanical engineering and various machinery, like internal combustion engines. They are also used in automatic lathe machines, diesel fuel pumps, and other repeating machinery and manufacturing applications.
Well, in this reading, we’ll explore what cam and follower are, their applications, functions, parts, diagram types and how they works. We’ll also explore their advantages and disadvantages.
What is Cam and Follower?
A cam and follower is a mechanism of a profiled shape that is designed to move a lever or follower. They are mounted on a shaft to convert rotary motion into linear (reciprocating) motion.
In their workings, the cam rotates causing the follower to rise and fall, which is known as reciprocating motion. Hence, the cam is a reciprocating, oscillating, or rotating body that affects the oscillating or reciprocating motion of the follower.
The design of a cam and follower can depends on the mechanism of the combination of both. The cam may depends on its own motion, or motion of the follower.
Cam Mechanism
A cam is a rotating element that offers reciprocating or oscillating motion to a follower which is an element of the machine by direct contact. A cam can also be said to be a mechanical member used to impart desired motion to a follower by direct contact.
These mechanisms can be used to transform rotary motion into linear to another part. This is why it can serve as a rotating wheel, an electric wheel, or a shaft that strikes a lever’s various points at its circular path.
Cams are also designed to be simple tooth often used to give pulses of power to a steam hammer. This shape can also be used in an eccentric disc which allows gentle reciprocating motion in the follower.
A cam can be used in a steam hammer as a simple tooth to deliver pulses of power. Also, it is often used in a shaft and rotating wheel like eccentric wheel, and a cylinder with irregular shape
The follower is expected to move smoothly without requiring too much input power. This will aid smooth working of the cam-follower mechanism. This will also avoid the follower from jamming while working.
Before the production of inexpensive electronics, cams are use as timer and are widely used to control electrical machines.
Follower Mechanism
A follower is a rotating or oscillating part of a machine that is moved by the cam’s motion due to direct contact between the two-part. Followers move vertically to the axis of the cam when the cam moves in a reciprocating motion.
The follower is part of a machine that follows the cam that is either oscillating or reciprocating in motion.
In brief, a driver member is a cam, while a driven member is known as a follower. There is always a frame that supports the cam and guides the follower.
The follower is used to transfer motion to required machine part as it rotate in a circular arc or oscillating. Followers are in direct contact with cam to achieve the up and down movement. Also, they can be in contact with the surface profile by spring-loaded.
Followers help to achieve complication output motion and they can have uniform velocity and uniform acceleration.
Functions of Cam and Follower
Below are the functions of a cam and follower mechanism in their various applications:
A cam-follower mechanism helps to achieve an even distribution of forces in a single machine component.
With a cylindrical roller in a machine component, spontaneous movement can be obtained. Cam-follower can be used to get varieties of linear motions when applied to a machine.
Due to the fact that the thickness of cam-follower is high compared to bearings, they tend to absorb a higher amount of shock. This helps to increase the mechanical efficiency of a machine component.
In addition, the system serves well on soda machines and aircraft applications, because the mechanism is versatile. It also serves well on a conveyor belt.
Applications
Below are the various applications of a cam and follower mechanism:
- Cam-follower is used in an internal combustion engine to open and close the outlet and intake valve using the camshaft.
- Used in a hydraulic system.
- Automated machinery makes good use of the mechanism.
- Printing machines also make good use of a cam-follower mechanism.
- Textile and agricultural equipment contain a cam and follower in them.
- Gear-cutting machinery.
- Automatic lathe machines.
- Wall-clocks.
Additionally, cam and follower mechanisms are used by engineers to ensure zero or minimum degree of error is obtained. In the automotive industry, a cam-follower mechanism is used to drive fuel pumps and also controls the valves.
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Parts and Diagram of Cam and Follower
The part of cam-follower can vary due to the fact that there are various types out there. So, below this article, we’ve explained the various types of cam and follower is explained with their various parts mentioned.
However, a cam-follower mechanism is developed by incorporating three members such as a driver member which is known as a cam, a frame that supports the cam and follower, and finally, the driven member known as a follower.
Cam-Follower Terminology
Terms like base circle, prime circle, pressure angle need to be understood when discussing cam follower mechanism. Well, below are cam-follower term you should know:
- Cam Profile – It is the surface area where a cam and follower touch.
- Base Circle – It is the smallest circle of a cam profile drawn from the center of rotation of the cam.
- Trace Point – this point allows the cam profile to be traced.
- Pitch Curve – This curve is generated if we assume the cam is fixed and the tracepoint of the follower moves around the cam.
- Pressure Angle – It is formed between the normal pitch curve and the line of motion of the follower.
- Pitch Point – it’s the point where the pressure angle is maximum.
- Pitch Circle – It is the circle that 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.
Types of Cams
Below are the various types of cams:
- Disk or Plate cam.
- Cylindrical cam.
- Translating cam.
- Wedge cam.
- Spiral cam.
- Heart-shaped cam.
- Conjugate cam
- Globoidal Cams
- Spherical cam
Disk or plate cams
A disk or plate type of cam has no regular contour to transmit a specific motion to the follower.
Cylindrical cams
Cylindrical cams have a groove in their cylindrical surface and the follower is designed to run on the cylindrical surface parallel to the axis of the cylinder.
Translating cam:
A translating cam also has a grooved or contoured plate as its follower oscillates in the face of the plate. The motion of the follower is specified by the groove or contour.
Wedge cams
A wedge cam has an angled flat regular contour so that a specific motion can be imparted to the follower.
Spiral cams
Spiral cams have a half-circular or a spiral shaping grooved contour, allowing it to move in a reciprocating motion. The follower moves vertically to the axis of the cam.
Heart-shaped Cams
This type of cam lookalike with an asymmetric heart, thus it’s named a heart-shaped cam. It is often used to return shafts to hold the cam to a set position by its pressure from a roller.
Conjugate Cams
In conjugate cam, 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. So as the cam rotates followers follow it.
Globoidal Cams
These types of cams are design with a shaft and has a concave or convex circumference. They have groove is made by machining and the groove is use for giving movement to the follower. It uses for oscillating followers about a fixed point.
Spherical Cams
A spherical cam is a spherical shape on which a groove is made and the follower has surface contact with this groove. As the cam rotates follower oscillates about a fixed point.
Types of Follower
Below are the various types of followers suitable for different cam motions:
Knife-edge Follower:
Knife-edge types of followers are designed with a sharp teeth area that contacts directly with the cam. It’s the simplest design among all of the followers and it cannot be used on applications that work with speed only slow ones, due to its sharp edge.
Roller Follower:
Roller followers are used in high-speed applications due to their smooth contact with the cam surface. Less wear and tear occur on this type of follower compared to the first one.
Flat-faced Follower:
These types of looks followers are similar to a flat surface with an irregular cam. It is used when space is limited in the mechanism and for resisting side thrust. This follower is also used on applications where precision is necessary.
Spherical Follower:
The spherical types of followers have a curve, it’s just a modification of a flat-faced follower.
Radial Follower:
A radial follower is similar to a spherical-faced follower, it has a line of movement that passes through the camshaft. The follower which is in a reciprocating motion has its movement in a line. It has the same diagram as the spherical-faced follower.
Offset Follower:
In this type of follower, the movement of the axis is not collinear with the cam axis.
How Does Cam and Follower Works?
The working of a cam-follower is less complex and can be easily understood. The mechanism depends on each other to work. This means where is cam there must be followers and vice versa else they are useless.
A cam is a mechanical component that rotates in a circular or eclipse about the minor axis of a follower. It can be explained as a mechanical device that transmits oscillating, reciprocating, or linear motion to a follower.
Cams are usually in an oval shape or an imperfect circle or an eclipse. When an oval-shaped cam is considered by an engineer, that means the movement requires an outer burgee, which is periodic to its locus.
The outer burgee is essential for works that are periodic mechanical. The cam is of two types; Single head and Multiple head cam.
In contrast to followers, it’s a part that inhibits push or pulls from a cam. It’s used to transfer motion to the required machine part. A follower rotates in an oscillating or circular arc.
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Cam and Follower Advantages and Disadvantages
Advantages:
• Converts rotary motion to reciprocating motion.
• Can achieve any desired follower motion.
• Can bear high vibrations.
• Accurate and versatile.
Disadvantages:
• Cam often subjected to wear and tear.
• High manufacturing cost and precise design.
• Consumes more space.