Centrifugal governor

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Centrifugal governor

A centrifugal governor is a specific type of governor

Governor (device)

A governor, or speed limiter, is a machine used to measure and regulate the speed of a machine, such as an engine. A classic example is the centrifugal governor, also known as the James Watt or fly-ball governor, which uses weights mounted on spring-loaded arms to determine how fast a shaft is spinning, and then uses proportional contr...
that controls the speed

Speed

Speed is the rate of Motion , or equivalently the rate of change of distance.Speed is a Scalar quantity with dimensions length/time; the equivalent Vector quantity to speed is velocity....
of an engine

Engine

An engine is a mechanical device that produces some form of output from a given input.An engine whose purpose is to produce kinetic energy output from a fuel is called a Wiktionary:prime mover; alternatively, a motor is a device which produces kinetic energy from a preprocessed "fuel" ....
by regulating the amount of fuel

Fuel

Fuel is any material that is burned or altered in order to obtain energy and to heat or to move an object. Fuel releases its energy either through a chemical reaction means, such as combustion, or nuclear means, such as nuclear fission or nuclear fusion....
(or working fluid

Working fluid

The working fluid in a machine is the pressurized gas or liquid which actuates the machine. Examples include steam in a steam engine, air in a hot air engine and hydraulic fluid in a hydraulic motor or hydraulic cylinder....
) admitted, so as to maintain a near constant speed whatever the load

Load

Load may refer to:*Structural load, forces which are applied to a structure*Cargo, Freight, or Lading*The load of a mutual fund *The genetic load of a population...
or fuel supply conditions. It uses the principle of proportional control

Proportional control

A proportional control system is a type of linear feedback control system. Two classic mechanical examples are the toilet bowl float proportioning valve and the Centrifugal governor....
.

It is most obviously seen on steam engine

Steam engine

File:Steam-powered fire engine.jpgA steam engine is a heat engine that performs mechanical work using steam as its working fluid.Steam engines have a long history, going back at least 2000 years....
s where it regulates the admission of steam into the cylinder

Cylinder (engine)

A cylinder is the central working part of a reciprocating engine, the space in which a piston travels. Multiple cylinders are commonly arranged side by side in a bank, or engine block, which is typically casting from aluminum or cast iron before precision features are machined into it....
(s).

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Operation

The device shown is from a steam engine. Power is supplied to the governor from the engine's output shaft by (in this instance) a belt or chain (not shown) connected to the lower belt wheel. The governor is connected to a throttle

Throttle

A throttle is the mechanism by which the flow of a fluid is managed by constriction or obstruction. An engine's power can be increased or decreased by the restriction of inlet gases ....
valve that regulates the flow of working fluid

Working fluid

Prime mover (locomotive)

In locomotives, the prime mover is the source of power for propulsion. The term is generally used when discussing any locomotive powered by an internal combustion engine....
(prime mover not shown). As the speed of the prime mover increases, the central spindle of the governor rotates at a faster rate and the kinetic energy of the balls increases. This allows the two mass

Mass

In physical science, mass refers to the degree of acceleration a body acquires when subject to a force: bodies with greater mass are accelerated less by the same force....
es on lever arms to move outwards and upwards against gravity. If the motion goes far enough, this motion causes the lever arms to pull down on a thrust bearing

Thrust bearing

A thrust bearing is a particular type of rotary bearing . Like other rotary bearings they permit rotation between parts, but they are designed to support a high axial load while doing this....
, which moves a beam linkage, which reduces the aperture

Aperture

In optics, an aperture is a hole or an opening through which light is admitted. More specifically, the aperture of an optical system is the opening that determines the cone angle of a bundle of ray that come to a focus in the ....
of a throttle valve. The rate of working-fluid entering the cylinder is thus reduced and the speed of the prime mover is controlled, preventing over-speeding.

Mechanical stops may be used to limit the range of throttle motion, as seen near the masses in the image at right.

The direction of the lever arm holding the mass will be along the vector sum of the reactive centrifugal force

Reactive centrifugal force

A reactive centrifugal force is the reaction force to a centripetal force.A mass undergoing circular motion constantly accelerates toward the axis of rotation....
vector and the gravitational force.

History

James Watt designed his first governor in 1788 following a suggestion from his business partner Matthew Boulton

Matthew Boulton

Matthew Boulton was an England manufacturer and engineer and a key member of the Lunar Society....
. It was a conical

Cone (geometry)

A cone is a dimension geometric shape that tapers smoothly from a flat, round base to a point called the apex or vertex. More precisely, it is the solid figure bounded by a plane base and the surface formed by the locus of all straight line segments joining the apex to the perimeter of the base....
pendulum governor and one of the final series of innovations Watt had employed for steam engines. James Watt never claimed the centrifugal governor to be an invention of his own. Centrifugal governors were used to regulate the distance and pressure between millstone

Millstone

Millstones or mill stones are used in windmills and watermills, including tide mills, for grinding wheat or other grains.The type of stone most suitable for making millstones is a siliceous rock called buhrstone , an open-textured, porous but tough, fine-grained sandstone, or a silicified, fossiliferous limestone....
s in windmill

Windmill

A windmill is a machine that is powered by the energy of the wind. It is designed to convert the energy of the wind into more useful forms using rotating blades or sails....
s since the 17th century. It is therefore a misunderstanding that James Watt is the inventor of this device.

A giant statue

Statue

A statue is a sculpture in the round representing a person or persons, an animal, or an event, normally full-length, as opposed to a Bust , and at least close to life-size, or larger....
of Watt's governor stands at Smethwick

Smethwick

Smethwick is a town in the Birmingham, in the West Midlands of England. It is situated on the edge of the city of Birmingham, within the Historic counties of England of Staffordshire....
in the English

England

West Midlands (county)

The West Midlands is a metropolitan county in West Midlands England with a population of 2,591,300. It came into existence as a metropolitan county in 1974 after the passage of the Local Government Act 1972....
. It is known as the flyball governor.

Another kind of centrifugal governor consists of a pair of masses on a spindle inside a cylinder, the masses or the cylinder being coated with pads, somewhat like a drum brake

Drum brake

A drum brake is a brake in which the friction is caused by a set of Brake shoe or Brake pad that press against the Brake lining of a rotating drum....
. This is used in a spring-loaded record player and a spring-loaded telephone

Telephone

The telephone is a telecommunications device that is used to transmitter and receive electronically or digitally encoded sound between two or more people conversing....
dial to limit the speed.

Dynamic systems

The centrifugal governor is often used in the cognitive sciences as an example of a dynamic system

Tim van Gelder

Tim van Gelder is an Australian Cognitive science. He is Principal Fellow in the University of Melbourne Department of Philosophy at the University of Melbourne, founder of Austhink Software, an Australian software development company, and Managing Director of Austhink Consulting....
, in which the representation of information cannot be clearly separated from the operations being applied to the representation. And because the governor is a servomechanism

Servomechanism

A servomechanism, or servo is an automatic device that uses error-sensing feedback to correct the performance of a mechanism. The term correctly applies only to systems where the feedback or error-correction signals help control mechanical position or other parameters....
, its analysis in a dynamic system is far from trivial. James Clerk Maxwell

James Clerk Maxwell

James Clerk Maxwell was a Scotland Mathematical physics. His most significant achievement was the development of the classical electromagnetic theory, synthesizing all previous unrelated observations, experiments and equations of electricity, magnetism and even optics into a consistent theory....
wrote a famous paper "On governors", which is quite frequently considered a classical paper in feedback control theory

Control theory

Control theory is an interdisciplinary branch of engineering and mathematics, that deals with the behavior of dynamical systems. The desired output of a system is called the reference....
, in 1868. Maxwell distinguishes moderators (a centrifugal brake

Brake

A brake is a device for applying a force against the friction of the road, slowing or stopping the motion of a machine or vehicle, or alternatively a device to restrain it from starting to move again....
) and governors which control motive power

Motive power

In thermodynamics, motive power is an agency, as water or steam, used to impart Motion . Generally, motive power is defined as a natural agent, as water, steam, wind, electricity, etc., used to impart motion to machinery; a motor; a mover....
input

Input

Input is the term denote either an entrance or changes which are inserted into a system and which activate/modify a process. It is an abstract concept, used in the model ing, system design and system exploitation....
. He considers devices by James Watt, Professor James Thomson

James Thomson (engineer)

James Thomson was an engineer and physicist whose reputation is substantial though it is overshadowed by that of his younger brother William Thomson, 1st Baron Kelvin....
, Fleeming Jenkin

Fleeming Jenkin

Henry Charles Fleeming Jenkin was Professor of Engineering at the University of Edinburgh, remarkable for his versatility. Known to the world as the inventor of telpherage, he was an electrician and cable engineer, a lecturer, linguist, critic, actor, dramatist and artist....
, William Thomson

William Thomson, 1st Baron Kelvin

William Thomson, 1st Baron Kelvin , Order of Merit , Royal Victorian Order, Privy Council of the United Kingdom, Presidents of the Royal Society, Royal Society of Edinburgh, was an Ireland-born United Kingdom of Great Britain and Ireland Mathematical physics and engineer....
, Leon Foucault

Léon Foucault

Jean Bernard L?on Foucault was a France physics best known for the invention of the Foucault pendulum, a device demonstrating the effect of the Earth's rotation....
and Carl Wilhelm Siemens

Carl Wilhelm Siemens

Carl Wilhelm Siemens was a Germany born engineer who for most of his life worked in United Kingdom and later became a British subject....
(a liquid governor).

In a largely overlooked passage of his famous 1858 paper to the Linnean Society

Linnean Society of London

The Linnean Society of London is the world's premier society for the study and dissemination of taxonomy and natural history. It publishes a Zoological Journal, as well as Botanical and Biological Journals....
(which led Darwin

Charles Darwin

Charles Robert Darwin Royal Society was an English people natural history who realised and presented compelling evidence that all species of life have evolution over time from common descent, through the process he called natural selection....
to publish his monumental On the Origin of Species) Wallace

Alfred Russel Wallace

Alfred Russel Wallace, Order of Merit, Fellow of the Royal Society was a United Kingdom of Great Britain and Ireland Natural history, explorer, geographer, anthropologist and biologist....
says of the evolutionary principle

Evolution

In biology, evolution is change in the heritability trait of a population of organisms from one generation to the next. These changes are caused by a combination of three main processes: variation, reproduction, and selection....
:

The action of this principle is exactly like that of the centrifugal governor of the steam engine, which checks and corrects any irregularities almost before they become evident; and in like manner no unbalanced deficiency in the animal kingdom can ever reach any conspicuous magnitude, because it would make itself felt at the very first step, by rendering existence difficult and extinction almost sure soon to follow..

The cybernetician

Cybernetics

Cybernetics is the interdisciplinary study of the structure of regulatory systems. Cybernetics is closely related to control theory and systems theory....
and anthropologist Gregory Bateson

Gregory Bateson

Gregory Bateson was a United Kingdom anthropology, social sciences, linguistics, semiotics and cybernetics whose work intersected that of many other fields....
would observe in the 1970s that though seeing it only as an illustration, Wallace had "probably said the most powerful thing that’d been said in the 19^th Century". Bateson revisited the topic in his 1979 book Mind and Nature: A Necessary Unity, and other scholars have continued to explore the connection between natural selection and systems theory

Systems theory

Systems theory is an interdisciplinary field of science and the study of the nature of complex systems in nature, society, and science. More specifically, it is a framework by which one can analyze and/or describe any group of objects that work in concert to produce some result....
.

Centrifugal governor

Operation

History

Dynamic systems

See also