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A machine uses power to apply forces and control movement to perform an intended action. Machines can be driven by animals and people, by natural forces such as wind and water, and by chemical, thermal, or electrical power, and include a system of mechanisms that shape the actuator input to achieve a specific application of output forces and movement. They can also include computers and sensors that monitor performance and plan movement, often called mechanical systems.

Renaissance natural philosophers identified six simple machines which were the elementary devices that put a load into motion, and calculated the ratio of output force to input force, known today as mechanical advantage.[1]

Modern machines are complex systems that consist of structural elements, mechanisms and control components and include interfaces for convenient use. Examples include a wide range of vehicles, such as automobiles, boats and airplanes, appliances in the home and office, building air handling and water handling systems, as well as farm machinery, machine tools and factory automation systems and robots.

Bonsack's machine
James Albert Bonsack's cigarette rolling machine, invented in 1880 and patented in 1881.


The English word machine comes through Middle French from Latin machina,[2] which in turn derives from the Greek (Doric μαχανά makhana, Ionic μηχανή mekhane "contrivance, machine, engine",[3] a derivation from μῆχος mekhos "means, expedient, remedy"[4]). The word mechanical comes from the same Greek roots. However, the Ancient Greeks probably have borrowed the word "mekhane" from the ancient Hebrews. The word "Mekhonot" plural and "Mekhona" singular mentioned in the Hebrew Bible - Torah; these "Mekhonot" were the ten contraption on four wheels that stood at the Holy Temple of Jerusalem, built by King Solomon-(2 Chronicles 4:14). The ancient Greeks were familiar with the Hebrew Scriptures and language, and often borrowed words and terms.

A wider meaning of "fabric, structure" is found in classical Latin, but not in Greek usage. This meaning is found in late medieval French, and is adopted from the French into English in the mid-16th century.

In the 17th century, the word could also mean a scheme or plot, a meaning now expressed by the derived machination. The modern meaning develops out of specialized application of the term to stage engines used in theater and to military siege engines, both in the late 16th and early 17th centuries. The OED traces the formal, modern meaning to John Harris' Lexicon Technicum (1704), which has:

Machine, or Engine, in Mechanicks, is whatsoever hath Force sufficient either to raise or stop the Motion of a Body... Simple Machines are commonly reckoned to be Six in Number, viz. the Ballance, Leaver, Pulley, Wheel, Wedge, and Screw... Compound Machines, or Engines, are innumerable.

The word engine used as a (near-)synonym both by Harris and in later language derives ultimately (via Old French) from Latin ingenium "ingenuity, an invention".


Flint hand axe found in Winchester

Perhaps the first example of a human made device designed to manage power is the hand axe, made by chipping flint to form a wedge. A wedge is a simple machine that transforms lateral force and movement of the tool into a transverse splitting force and movement of the workpiece.

The idea of a simple machine originated with the Greek philosopher Archimedes around the 3rd century BC, who studied the Archimedean simple machines: lever, pulley, and screw.[5][6] He discovered the principle of mechanical advantage in the lever.[7] Later Greek philosophers defined the classic five simple machines (excluding the inclined plane) and were able to roughly calculate their mechanical advantage.[1] Heron of Alexandria (ca. 10–75 AD) in his work Mechanics lists five mechanisms that can "set a load in motion"; lever, windlass, pulley, wedge, and screw,[6] and describes their fabrication and uses.[8] However the Greeks' understanding was limited to statics (the balance of forces) and did not include dynamics (the tradeoff between force and distance) or the concept of work.

During the Renaissance the dynamics of the Mechanical Powers, as the simple machines were called, began to be studied from the standpoint of how much useful work they could perform, leading eventually to the new concept of mechanical work. In 1586 Flemish engineer Simon Stevin derived the mechanical advantage of the inclined plane, and it was included with the other simple machines. The complete dynamic theory of simple machines was worked out by Italian scientist Galileo Galilei in 1600 in Le Meccaniche ("On Mechanics").[9][10] He was the first to understand that simple machines do not create energy, they merely transform it.[9]

The classic rules of sliding friction in machines were discovered by Leonardo da Vinci (1452–1519), but remained unpublished in his notebooks. They were rediscovered by Guillaume Amontons (1699) and were further developed by Charles-Augustin de Coulomb (1785).[11]

James Watt patented his parallel motion linkage in 1782, which made the double acting steam engine practical.[12] The Boulton and Watt steam engine and later designs powered steam locomotives, steam ships, and factories.

The Industrial Revolution was a period from 1750 to 1850 where changes in agriculture, manufacturing, mining, transportation, and technology had a profound effect on the social, economic and cultural conditions of the times. It began in the United Kingdom, then subsequently spread throughout Western Europe, North America, Japan, and eventually the rest of the world.

Starting in the later part of the 18th century, there began a transition in parts of Great Britain's previously manual labour and draft-animal–based economy towards machine-based manufacturing. It started with the mechanisation of the textile industries, the development of iron-making techniques and the increased use of refined coal.[13]

Simple machines

Table of simple mechanisms, from Chambers' Cyclopædia, 1728.[14] Simple machines provide a "vocabulary" for understanding more complex machines.

The idea that a machine can be decomposed into simple movable elements led Archimedes to define the lever, pulley and screw as simple machines. By the time of the Renaissance this list increased to include the wheel and axle, wedge and inclined plane. The modern approach to characterizing machines focusses on the components that allow movement, known as joints.

Wedge (hand axe): Perhaps the first example of a device designed to manage power is the hand axe, also see biface and Olorgesailie. A hand axe is made by chipping stone, generally flint, to form a bifacial edge, or wedge. A wedge is a simple machine that transforms lateral force and movement of the tool into a transverse splitting force and movement of the workpiece. The available power is limited by the effort of the person using the tool, but because power is the product of force and movement, the wedge amplifies the force by reducing the movement. This amplification, or mechanical advantage is the ratio of the input speed to output speed. For a wedge this is given by 1/tanα, where α is the tip angle. The faces of a wedge are modeled as straight lines to form a sliding or prismatic joint.

Lever: The lever is another important and simple device for managing power. This is a body that pivots on a fulcrum. Because the velocity of a point farther from the pivot is greater than the velocity of a point near the pivot, forces applied far from the pivot are amplified near the pivot by the associated decrease in speed. If a is the distance from the pivot to the point where the input force is applied and b is the distance to the point where the output force is applied, then a/b is the mechanical advantage of the lever. The fulcrum of a lever is modeled as a hinged or revolute joint.

Wheel: The wheel is clearly an important early machine, such as the chariot. A wheel uses the law of the lever to reduce the force needed to overcome friction when pulling a load. To see this notice that the friction associated with pulling a load on the ground is approximately the same as the friction in a simple bearing that supports the load on the axle of a wheel. However, the wheel forms a lever that magnifies the pulling force so that it overcomes the frictional resistance in the bearing.

Illustration of a Four-bar linkage from Kinematics of Machinery, 1876
Illustration of a four-bar linkage from Kinematics of Machinery, 1876

The classification of simple machines to provide a strategy for the design of new machines was developed by Franz Reuleaux, who collected and studied over 800 elementary machines. He recognized that the classical simple machines can be separated into the lever, pulley and wheel and axle that are formed by a body rotating about a hinge, and the inclined plane, wedge and screw that are similarly a block sliding on a flat surface.[15]

Simple machines are elementary examples of kinematic chains or linkages that are used to model mechanical systems ranging from the steam engine to robot manipulators. The bearings that form the fulcrum of a lever and that allow the wheel and axle and pulleys to rotate are examples of a kinematic pair called a hinged joint. Similarly, the flat surface of an inclined plane and wedge are examples of the kinematic pair called a sliding joint. The screw is usually identified as its own kinematic pair called a helical joint.

This realization shows that it is the joints, or the connections that provide movement, that are the primary elements of a machine. Starting with four types of joints, the rotary joint, sliding joint, cam joint and gear joint, and related connections such as cables and belts, it is possible to understand a machine as an assembly of solid parts that connect these joints called a mechanism .[16]

Two levers, or cranks, are combined into a planar four-bar linkage by attaching a link that connects the output of one crank to the input of another. Additional links can be attached to form a six-bar linkage or in series to form a robot.[16]


Mechanical system

The adjective "mechanical" refers to skill in the practical application of an art or science, as well as relating to or caused by movement, physical forces, properties or agents such as is dealt with by mechanics.[17] Similarly Merriam-Webster Dictionary[18] defines "mechanical" as relating to machinery or tools.

Power flow through a machine provides a way to understand the performance of devices ranging from levers and gear trains to automobiles and robotic systems. The German mechanician Franz Reuleaux[19] wrote "a machine is a combination of resistant bodies so arranged that by their means the mechanical forces of nature can be compelled to do work accompanied by certain determinate motion." Notice that forces and motion combine to define power.

More recently, Uicker et al.[16] stated that a machine is "a device for applying power or changing its direction." And McCarthy and Soh[20] describe a machine as a system that "generally consists of a power source and a mechanism for the controlled use of this power."

Engine and Motor

An engine or motor is a machine designed to convert energy into useful mechanical motion.[21][22] Heat engines, including internal combustion engines and external combustion engines (such as steam engines) burn a fuel to create heat, which is then used to create motion. Electric motors convert electrical energy into mechanical motion, pneumatic motors use compressed air and others, such as wind-up toys use elastic energy. In biological systems, molecular motors like myosins in muscles use chemical energy to create motion.

An electrical machine is the generic name for a device that converts mechanical energy to electrical energy, converts electrical energy to mechanical energy.

Computing machines

Arithmometr computing machine
Arithmometre, designed by Charles Xavier Thomas, c. 1820, for the four rules of arithmetic, manufactured 1866-1870 AD. Exhibit in the Tekniska museet, Stockholm, Sweden.

Charles Babbage designed machines to tabulate logarithms and other functions in 1837. His Difference engine can be considered an advanced mechanical calculator and his Analytical Engine a forerunner of the modern computer, though none were built in Babbage's lifetime.

The Arithmometer and the Comptometer are mechanical computers that are precursors to modern digital computers. Models used to study modern computers are termed State machine and Turing machine.

Molecular machines

The biological molecule myosin reacts to ATP and ADP to alternately engage with an actin filament and change its shape in a way that exerts a force, and then disengage to reset its shape, or conformation. This acts as the molecular drive that causes muscle contraction. Similarly the biological molecule kinesin has two sections that alternately engage and disengage with microtubules causing the molecule to move along the microtubule and transport vesicles within the cell. These molecules are increasingly considered to be nanomachines.

Researchers have used DNA to construct nano-dimensioned four-bar linkages.[23][24]

Machine elements

Machines are assembled from standardized types of components. These elements consist of mechanisms that control movement in various ways such as gear trains, belt or chain drives, linkages, cam and follower systems, brakes and clutches, and structural components such as frame members and fasteners.

Modern machines include sensors, actuators and computer controllers. The shape, texture and color of covers provide a styling and operational interface between the mechanical components of a machine and its users.


Assemblies within a machine that control movement are often called "mechanisms." [25][26] Mechanisms are generally classified as gears and gear trains, cam and follower mechanisms, and linkages, though there are other special mechanisms such as clamping linkages, indexing mechanisms and friction devices such as brakes and clutches. For more details see Machine (mechanical) and Mechanical systems.


Controllers combine sensors, logic, and actuators to maintain the performance of components of a machine. Perhaps the best known is the flyball governor for a steam engine. Examples of these devices range from a thermostat that as temperature rises opens a valve to cooling water to speed controllers such the cruise control system in an automobile. The programmable logic controller replaced relays and specialized control mechanisms with a programmable computer. Servo motors that accurately position a shaft in response to an electrical command are the actuators that make robotic systems possible.


Mechanization and automation

A water-powered mine hoist used for raising ore. This woodblock is from De re metallica by Georg Bauer (Latinized name Georgius Agricola, ca. 1555) an early mining textbook that contains numerous drawings and descriptions of mining equipment.

Mechanization or mechanisation (BE) is providing human operators with machinery that assists them with the muscular requirements of work or displaces muscular work. In some fields, mechanization includes the use of hand tools. In modern usage, such as in engineering or economics, mechanization implies machinery more complex than hand tools and would not include simple devices such as an un-geared horse or donkey mill. Devices that cause speed changes or changes to or from reciprocating to rotary motion, using means such as gears, pulleys or sheaves and belts, shafts, cams and cranks, usually are considered machines. After electrification, when most small machinery was no longer hand powered, mechanization was synonymous with motorized machines.[27]

Automation is the use of control systems and information technologies to reduce the need for human work in the production of goods and services. In the scope of industrialization, automation is a step beyond mechanization. Whereas mechanization provides human operators with machinery to assist them with the muscular requirements of work, automation greatly decreases the need for human sensory and mental requirements as well. Automation plays an increasingly important role in the world economy and in daily experience.


An automaton (plural: automata or automatons) is a self-operating machine. The word is sometimes used to describe a robot, more specifically an autonomous robot. An alternative spelling, now obsolete, is automation.[28]

See also


  1. ^ a b Usher, Abbott Payson (1988). A History of Mechanical Inventions. USA: Courier Dover Publications. p. 98. ISBN 0-486-25593-X. 
  2. ^ The American Heritage Dictionary, Second College Edition. Houghton Mifflin Co., 1985.
  3. ^ "μηχανή", Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus project
  4. ^ "μῆχος", Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus project
  5. ^ Asimov, Isaac (1988), Understanding Physics, New York, New York, USA: Barnes & Noble, p. 88, ISBN 0-88029-251-2. 
  6. ^ a b Chiu, Y. C. (2010), An introduction to the History of Project Management, Delft: Eburon Academic Publishers, p. 42, ISBN 90-5972-437-2 
  7. ^ Ostdiek, Vern; Bord, Donald (2005). Inquiry into Physics. Thompson Brooks/Cole. p. 123. ISBN 0-534-49168-5. Retrieved 2008-05-22. 
  8. ^ Strizhak, Viktor; Igor Penkov; Toivo Pappel (2004). "Evolution of design, use, and strength calculations of screw threads and threaded joints". HMM2004 International Symposium on History of Machines and Mechanisms. Kluwer Academic publishers. p. 245. ISBN 1-4020-2203-4. Retrieved 2008-05-21. 
  9. ^ a b Krebs, Robert E. (2004). Groundbreaking Experiments, Inventions, and Discoveries of the Middle Ages. Greenwood Publishing Group. p. 163. ISBN 0-313-32433-6. Retrieved 2008-05-21. 
  10. ^ Stephen, Donald; Lowell Cardwell (2001). Wheels, clocks, and rockets: a history of technology. USA: W. W. Norton & Company. pp. 85–87. ISBN 0-393-32175-4. 
  11. ^ Armstrong-Hélouvry, Brian (1991). Control of machines with friction. USA: Springer. p. 10. ISBN 0-7923-9133-0. 
  12. ^ Pennock, G. R., James Watt (1736-1819), Distinguished Figures in Mechanism and Machine Science, ed. M. Ceccarelli, Springer, 2007, ISBN: 978-1-4020-6365-7 (Print) 978-1-4020-6366-4 (Online).
  13. ^ Beck B., Roger (1999). World History: Patterns of Interaction. Evanston, Illinois: McDougal Littell. 
  14. ^ Chambers, Ephraim (1728), "Table of Mechanicks", Cyclopaedia, A Useful Dictionary of Arts and Sciences, London, England, Volume 2, p. 528, Plate 11 .
  15. ^ Hartenberg, R.S. & J. Denavit (1964) Kinematic synthesis of linkages, New York: McGraw-Hill, online link from Cornell University.
  16. ^ a b c J. J. Uicker, G. R. Pennock, and J. E. Shigley, 2003, Theory of Machines and Mechanisms, Oxford University Press, New York.
  17. ^ Oxford English Dictionary
  18. ^ Merriam-Webster Dictionary Definition of mechanical
  19. ^ Reuleaux, F., 1876 The Kinematics of Machinery, (trans. and annotated by A. B. W. Kennedy), reprinted by Dover, New York (1963)
  20. ^ J. M. McCarthy and G. S. Soh, 2010, Geometric Design of Linkages, Springer, New York.
  21. ^ "Motor". Retrieved 2011-05-09. a person or thing that imparts motion, esp. a contrivance, as a steam engine, that receives and modifies energy from some natural source in order to utilize it in driving machinery. 
  22. ^ (World heritage) "3. any device that converts another form of energy into mechanical energy to produce motion"
  23. ^ Marras, A., Zhou, L., Su, H., and Castro, C.E. Programmable motion of DNA origami mechanisms, Proceedings of the National Academy of Sciences, 2015
  24. ^ McCarthy, C, DNA Origami Mechanisms and Machines | Mechanical Design 101, 2014
  25. ^ Reuleaux, F., 1876 The Kinematics of Machinery, (trans. and annotated by A. B. W. Kennedy), reprinted by Dover, New York (1963)
  26. ^ J. J. Uicker, G. R. Pennock, and J. E. Shigley, 2003, Theory of Machines and Mechanisms, Oxford University Press, New York.
  27. ^ Jerome (1934) gives the industry classification of machine tools as being "other than hand power". Beginning with the 1900 U.S. census, power use was part of the definition of a factory, distinguishing it from a workshop.
  28. ^ "U.S. Patent and Trademark Office, Patent# 40891, Toy Automation". Google Patents. Retrieved 2007-01-07. 

Further reading

  • Oberg, Erik; Franklin D. Jones; Holbrook L. Horton; Henry H. Ryffel (2000). Christopher J. McCauley; Riccardo Heald; Muhammed Iqbal Hussain, eds. Machinery's Handbook (26th ed.). New York: Industrial Press Inc. ISBN 0-8311-2635-3. 
  • Reuleaux, Franz (1876). The Kinematics of Machinery. Trans. and annotated by A. B. W. Kennedy. New York: reprinted by Dover (1963). 
  • Uicker, J. J.; G. R. Pennock; J. E. Shigley (2003). Theory of Machines and Mechanisms. New York: Oxford University Press.