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.
James Albert Bonsack's cigarette rolling machine, invented in 1880 and patented in 1881
1 Etymology 2 History 3 Simple machines 4 Mechanical systems 5 Power sources 6 Mechanisms
6.1 Structural components
7 Controllers 8 Computing machines 9 Molecular machines 10 Impact
11.1 Dynamics of machines
The English word machine comes through
Middle French from Latin
machina, which in turn derives from the Greek (Doric μαχανά
makhana, Ionic μηχανή mekhane "contrivance, machine, engine",
a derivation from μῆχος mekhos "means, expedient, remedy").
The word mechanical comes from the same Greek roots. However, the
Ancient Greeks probably 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
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
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
This section needs expansion. You can help by adding to it. (March 2012)
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
Table of simple mechanisms, from Chambers' Cyclopædia, 1728.
The idea that a machine can be decomposed into simple movable elements
Illustration of a four-bar linkage from The
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.
The Boulton & Watt Steam Engine, 1784
Modern machines are systems consisting of (i) a power source and actuators that generate forces and movement, (ii) a system of mechanisms that shape the actuator input to achieve a specific application of output forces and movement, (iii) a controller with sensors that compare the output to a performance goal and then directs the actuator input, and (iv) an interface to an operator consisting of levers, switches, and displays. This can be seen in Watt's steam engine (see the illustration) in which the power is provided by steam expanding to drive the piston. The walking beam, coupler and crank transform the linear movement of the piston into rotation of the output pulley. Finally, the pulley rotation drives the flyball governor which controls the valve for the steam input to the piston cylinder. 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. Similarly Merriam-Webster Dictionary 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 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. stated that a machine is "a device for applying power or changing its direction." McCarthy and Soh describe a machine as a system that "generally consists of a power source and a mechanism for the controlled use of this power." Power sources Human and animal effort were the original power sources for early machines. Natural forces such as wind and water powered larger mechanical systems. Waterwheel: Waterwheels appeared around the world around 300 BC to use flowing water to generate rotary motion, which was applied to milling grain, and powering lumber, machining and textile operations. Modern water turbines use water flowing through a dam to drive an electric generator. Windmill: Early windmills captured wind power to generate rotary motion for milling operations. Modern wind turbines also drives a generator. This electricity in turn is used to drive motors forming the actuators of mechanical systems. Engine: The word engine derives from "ingenuity" and originally referred to contrivances that may or may not be physical devices. See Merriam-Webster's definition of engine. A steam engine uses heat to boil water contained in a pressure vessel; the expanding steam drives a piston or a turbine. This principle can be seen in the aeolipile of Hero of Alexandria. This is called an external combustion engine. An automobile engine is called an internal combustion engine because it burns fuel (an exothermic chemical reaction) inside a cylinder and uses the expanding gases to drive a piston. A jet engine uses a turbine to compress air which is burned with fuel so that it expands through a nozzle to provide thrust to an aircraft, and so is also an "internal combustion engine."  Power plant: The heat from coal and natural gas combustion in a boiler generates steam that drives a steam turbine to rotate an electric generator. A nuclear power plant uses heat from a nuclear reactor to generate steam and electric power. This power is distributed through a network of transmission lines for industrial and individual use. Motors: Electric motors use either AC or DC electric current to generate rotational movement. Electric servomotors are the actuators for mechanical systems ranging from robotic systems to modern aircraft. Fluid Power: Hydraulic and pneumatic systems use electrically driven pumps to drive water or air respectively into cylinders to power linear movement. Mechanisms The mechanism of a mechanical system is assembled from components called machine elements. These elements provide structure for the system and control its movement. The structural components are, generally, the frame members, bearings, splines, springs, seals, fasteners and covers. The shape, texture and color of covers provide a styling and operational interface between the mechanical system and its users. The assemblies that control movement are also called "mechanisms."  Mechanisms are generally classified as gears and gear trains, which includes belt drives and chain drives, cam and follower mechanisms, and linkages, though there are other special mechanisms such as clamping linkages, indexing mechanisms, escapements and friction devices such as brakes and clutches. The number of degrees of freedom of a mechanism, or its mobility, depends on the number of links and joints and the types of joints used to construct the mechanism. The general mobility of a mechanism is the difference between the unconstrained freedom of the links and the number of constraints imposed by the joints. It is described by the Chebychev-Grübler-Kutzbach criterion. Structural components A number of machine elements provide important structural functions such as the frame, bearings, splines, spring and seals.
The recognition that the frame of a mechanism is an important machine element changed the name three-bar linkage into four-bar linkage. Frames are generally assembled from truss or beam elements. Bearings are components designed to manage the interface between moving elements and are the source of friction in machines. In general, bearings are designed for pure rotation or straight line movement. Splines and keys are two ways to reliably mount an axle to a wheel, pulley or gear so that torque can be transferred through the connection. Springs provides forces that can either hold components of a machine in place or acts as a suspension to support part of a machine. Seals are used between mating parts of a machine to ensure fluids, such as water, hot gases, or lubricant do not leak between the mating surfaces. Fasteners such as screws, bolts, spring clips, and rivets are critical to the assembly of components of a machine. Fasteners are generally considered to be removable. In contrast, joining methods, such as welding, soldering, crimping and the application of adhesives, usually require cutting the parts to disassemble the components
Controllers 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 as the cruise control system in an automobile. The programmable logic controller replaced relays and specialized control mechanisms with a programmable computer. Servomotors that accurately position a shaft in response to an electrical command are the actuators that make robotic systems possible. Computing machines
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.
A water-powered mine hoist used for raising ore. This woodblock is
De re metallica
invention, which involves the identification of a need, development of requirements, concept generation, prototype development, manufacturing, and verification testing; performance engineering involves enhancing manufacturing efficiency, reducing service and maintenance demands, adding features and improving effectiveness, and validation testing; recycle is the decommissioning and disposal phase and includes recovery and reuse of materials and components.
See also Main articles: Outline of machines and Outline of industrial machinery
History of technology
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Wikimedia Commons has media related to Machines.
v t e
Classical simple machines
Atomic clock Chronometer Pendulum clock Quartz clock
Compressors and pumps
Archimedes' screw Eductor-jet pump Hydraulic ram Pump Trompe Vacuum pump
External combustion engines
Steam engine Stirling engine
Internal combustion engines
Reciprocating engine Gas turbine
Gas turbine Jet engine Steam turbine Water turbine Wind generator Windmill
Sail Wing Rudder Flap Propeller
Vacuum tube Transistor Diode Resistor Capacitor Inductor
Mecha Robot Vending machine Wind tunnel Check weighing machines Riveting machines
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