View source for Centrifugal governor

{{Short description|Mechanism for automatically controlling the speed of an engine}}
{{use dmy dates|date=October 2025}}
{{refimprove|date=October 2025}}
[[Image:centrifugal governor.png|right|thumb|Drawing of a centrifugal "fly-ball" governor, where the balls swing out as speed increases, which closes the valve, until a balance is achieved between demand and the proportional gain of the linkage and valve.{{cn|date=October 2025}}]]

A '''centrifugal governor''' is a specific type of [[governor (device)|governor]] with a feedback system that controls the speed of an [[engine]] by regulating the flow of [[fuel]] or [[working fluid]], so as to maintain a near-constant speed. It uses the principle of [[proportional control]].{{citation needed lead|date=October 2025}}

A centrifugal governor was invented by [[Christiaan Huygens|Huygens]] in the seventeenth century, where it was used "for the regulation of windmills and water wheels".<ref name="Hills">{{citation|last=Hills|first=Richard L.|authorlink=Richard L. Hills|year=1996 | title=Power From Wind | page =  | location = Cambridge, England | publisher=Cambridge University Press | isbn =  | url =  | access-date =  }}{{full|date=October 2025}}</ref>{{page needed|date=October 2025}}<ref>{{cite book| author = Bellman, Richard E. | date=8 December 2015| title=Adaptive Control Processes: A Guided Tour| page = 36 | isbn=9781400874668 | location = Princeton, NJ | publisher=Princeton University Press| url=https://books.google.com/books?id=iwbWCgAAQBAJ&q=%22Centrifugal+Governor%22+Huygens&pg=PA36 |access-date=13 April 2018| quote = ...centrifugal governor was invented by C. Huygens for the regulation of windmills and water wheels in the seventeenth century.}} Note, the quote reflects the entirely of the usable material at this source link. (Only a limited view is available at the Google Books entry.)</ref> The devices are also known as "centrifugal regulators" and "fly-ball governors".{{citation needed lead|date=October 2025}}<!--This material not in Hills.--> In 1788, [[James Watt]] adapted one to control his [[steam engine]], where it regulated the admission of steam into the engine's [[cylinder (engine)|cylinder]]s.<ref>{{cite web|author = Gee, Andrew H. | date = November 2024 | title = Preparing for the Week 1 Lego Exercise: The Sizzling Steam Engine | work = Cambridge University Engineering Department (mi.eng.cam.ac.uk) | url = http://mi.eng.cam.ac.uk/IALego/steam.html | location = Cambridge, England | publisher = University of Cambridge}} For author, date, and other general bibliographic details, see [https://mi.eng.cam.ac.uk/IALego/ this link], that is nested in the first.</ref>{{better source|date=October 2025}} This development proved so important that Watt is sometimes called the inventor.{{cn|date=October 2025}} Centrifugal governors' widest use was on steam engines during the [[Steam power during the Industrial Revolution|Steam Age]] in the 19th century. They are also found on [[Stationary engine|stationary]] [[internal combustion engine]]s, variously fueled [[turbine]]s, and in some modern [[striking clock]]s.{{citation needed lead|date=October 2025}}

A simple governor does not maintain an exact speed but a speed range,{{citation needed lead|date=October 2025}} since under increasing load the governor opens the throttle as the speed (RPM) decreases.{{citation needed lead|date=October 2025}}
<!--No mention of any of the tagged content in the article, so all unsourced editorialising, [[WP:OR]].-->

==Operation==
===Sourced descriptions===
{{expand section | with = up-to-date examples of sources of schematics with detailed description of the Watt and other centrifugal governor designs | small = no|date=October 2025}}
A detailed description of an example of a centrifugal governor, with a fully labeled schematic, appears in the article on "Angular Motion, or Velocity", in [[Oliver Byrne]]'s edition of ''Spons' Dictionary of Engineering'', with further elaboration in the article on "Governors" (in a later volume).<ref name=SponByrneV1>{{cite book | author = Spon, Edward; Byrne, Oliver; Spon, Ernest | date = 1871 | title = Spons' Dictionary of Engineering, Civil, Mechanical, Military, and Naval; with Technical Terms in French, German, Italian, and Spanish | volume = 1 | page = 101-103 | location = London & New York | publisher = E. & F.N. Spon | url = https://archive.org/details/sponsdictionaryo01spon/page/102/mode/1up | access-date = 27 October 2025}}</ref>{{update after|2025|10|27}}

===Detailed description of operation===
[[File:Centrifugal governor and balanced steam valve (New Catechism of the Steam Engine, 1904).jpg|thumb|upright|Cut-away drawing of a steam engine speed governor.{{Clarify|date=October 2025|reason= Both governor design (whose?) and source of description are needed.}}{{cn|date=October 2025}} The drive shaft whose speed is being sensed is at top right. The valve starts fully open at zero speed, but as the balls rotate and rise, the central [[valve stem]] is forced downward and closes the valve.{{cn|date=October 2025}}]]
{{multiple issues|section = yes|
{{unreferenced section|date=October 2025}}
{{original research|section|certain=yes|date=October 2025}}
}}
The device shown is on a steam engine;{{cn|date=October 2025}} power is supplied to the governor from the engine's output shaft by a belt or chain connected to the lower belt wheel{{what|date=October 2025}}, and the governor is connected to a [[throttle]] valve{{what|date=October 2025}} that regulates the flow of [[working fluid]] (steam) supplying the [[Prime mover (locomotive)|prime mover]].{{what|date=October 2025}}{{Synthesis inline|sure = yes | reason = Here and following, the specific design (Watt, others) must be stated, as should the source of the description of operation | date=October 2025}} 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]]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]], which moves a beam linkage, which reduces the [[aperture]] 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 the top of this page.

====Non-gravitational regulation====
{{Improve images |reason=This subsection needs an image of a non-vertical regulator design to appear with this description, and the description should then be matched to the image.|date=October 2025}}
A limitation of the two-arm, two-ball governor is its reliance on gravity to retract the balls when the governor slows down, and therefore a requirement that the governor stay upright.{{says who|date=October 2025}}{{cn|date=October 2025}} Governors have been built that do not use gravitational force, using a single straight arm with weights on both ends, a center pivot attached to a spinning axle, and a spring that tries to force the weights towards the center of the spinning axle.{{what|date=October 2025}}{{Synthesis inline|sure = yes | reason = Here and following, the specific inventor's governor design must be stated, as should the source of the description of operation | date=October 2025}} The two weights on opposite ends of the pivot arm counterbalance any gravitational effects, but both weights use centrifugal force to work against the spring and attempt to rotate the pivot arm towards a perpendicular axis relative to the spinning axle.

Spring-retracted non-gravitational governors{{what|date=October 2025}} are commonly used in [[Single-phase electric power|single-phase]] [[alternating current]] (AC) [[induction motor]]s to turn off the starting [[field coil]] when the motor's rotational speed is high enough.{{cn|date=October 2025}} They are also commonly used in [[snowmobile]] and [[all-terrain vehicle]] (ATV) [[continuously variable transmission]]s (CVT), both to engage/disengage vehicle motion and to vary the transmission's pulley diameter ratio in relation to the engine [[revolutions per minute]].{{says who|date=October 2025}}{{cn|date=October 2025}}

==History==
[[File:Centrifugal governor in Sluis, Netherlands.JPG|thumb|right|A millstone governor at [[Sluis]], in the [[Netherlands]]{{cn|date=October 2025}}]]

A centrifugal governor was invented by [[Christiaan Huygens|Huygens]] in the seventeenth century, where it was used "for the regulation of windmills and water wheels".<ref name="Hills">{{citation|last=Hills|first=Richard L.|authorlink=Richard L. Hills|year=1996 | title=Power From Wind | page =  | location = Cambridge, England | publisher=Cambridge University Press | isbn =  | url =  | access-date =  }}{{full|date=October 2025}}</ref>{{page needed|date=October 2025}}<ref>{{cite book| author = Bellman, Richard E. | date=8 December 2015| title=Adaptive Control Processes: A Guided Tour| page = 36 | isbn=9781400874668 | location = Princeton, NJ | publisher=Princeton University Press| url=https://books.google.com/books?id=iwbWCgAAQBAJ&q=%22Centrifugal+Governor%22+Huygens&pg=PA36 |access-date=13 April 2018| quote = ...centrifugal governor was invented by C. Huygens for the regulation of windmills and water wheels in the seventeenth century.}} Note, the quote reflects the entirely of the usable material at this source link. (Only a limited view is available at the Google Books entry.)</ref> also known as "centrifugal regulators" and "fly-ball governors" in that application,{{cite quote|date=October 2025}} the governor was used to regulate the distance and pressure between [[Millstone#Grinding_with_millstones|millstones]].{{cn|date=October 2025}}<!--This material not in Hills.-->

[[File:Boulton and Watt centrifugal governor-MJ.jpg|thumb|left|upright|Boulton & Watt engine of 1788]]
James Watt applied the same technology to steam engines.<ref name="Hannavy2021">{{cite book |last1=Hannavy |first1=John |title=The Governor: Controlling the Power of Steam Machines |date=2021 |publisher=Pen & Sword Transport |location=Barnsley, S. Yorks. |pages=60–78}}</ref> He designed his first governor (or 'centrifugal speed regulator') in 1788, following a suggestion from his business partner [[Matthew Boulton]]; it was a [[conical pendulum]] governor, and one of the final series of innovations Watt had employed for steam engines.{{cn|date=October 2025}}
<!--Here and following, if the source of all of this is "Hannavy2021", then that <ref name=...> should appear after each factual statement. (The article is rife with unsourced content, so when there is a source, we need to know it.) If so, this also will make clear that {{one source|section}} applies, so editors can seek to broaden the section's sourcing.-->

Over subsequent decades a series of improvements and modifications were made by a number of different engineers and manufacturers. Among the inventors who contributed to development of the governor in the 19th century were Charles Porter, Wilson Hartnell, [[Richard Tangye]], Rudolph Proell and Buss.<ref name="Hannavy2021" />

[[File: Ashton Frost engine governor.jpg|thumb|upright|A Porter governor on a [[Corliss steam engine]]. This design, patented by Charles Porter in 1858, used lighter balls and a sliding weight on the spindle; it suited faster engines.]]
As engine speeds increased, the basic Watt-type governor became less reliable as it would tend to over-compensate, [[oscillating]] between opening and closing the steam valve and preventing the engine from running smoothly.<ref name="Hannavy2021" /> This led to many modifications and variations over time, including the addition of a dead weight around the spindle, and the application of springs as part of the design.{{cn|date=October 2025}} A number of different firms of engineers patented their own variation on the concept, which they would apply to their own engines, and more modern governors were sometimes retrofitted to engines already in service.{{cn|date=October 2025}}

[[File:Governor - 17836825593.jpg|thumb|upright|left|The Pickering Governor (first patented in 1862) has balls mounted on [[leaf springs]]. It was especially suited to smaller high-speed engines and was manufactured in large numbers.]]

==Uses==
{{unreferenced section|date=October 2025}}
Centrifugal governors' widest use was on steam engines during the [[Steam power during the Industrial Revolution|Steam Age]] in the 19th century. They are also found on [[Stationary engine|stationary]] [[internal combustion engine]]s and variously fueled [[turbine]]s, and in some modern [[striking clock]]s.

Centrifugal governors are used in many modern [[Repeater (horology)|repeating watches]] to limit the speed of the [[Striking clock#Parts of mechanism|striking train]], so the repeater does not run too quickly.

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 [[centrifugal clutch]] or a [[drum brake]]. This is used in a spring-loaded [[record player]] and a spring-loaded [[telephone]] dial to limit the speed.

==Dynamic systems==
[[File:Ellenroad Engine House - large steam engine governor - geograph.org.uk - 7349748.jpg|thumb|right|upright|The spring-loaded Whitehead governor, patented in 1895, was widely used on mill engines (as here at [[Ellenroad Ring Mill Engine|Ellenroad]]).]]
The centrifugal governor is often used in the cognitive sciences as an example of a [[dynamic system]], 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]], its analysis in a dynamic system is not trivial.  In 1868, [[James Clerk Maxwell]] wrote a famous paper [[:File:On Governors.pdf|"''On Governors''"]]<ref>{{cite journal|last=Maxwell|first=James Clerk|title=On Governors|journal=Proceedings of the Royal Society of London|volume= 16|year= 1868 |pages= 270–283 | doi = 10.1098/rspl.1867.0055 | jstor=112510|doi-access=}}</ref>{{primary source inline|date=October 2025}} that is widely considered a classic in feedback [[control theory]].{{weasel words inline|date=October 2025}}{{editorializing|date=October 2025}}{{cn|date=October 2025}} Maxwell distinguishes moderators (a centrifugal [[brake]]) and governors which control [[Power (physics)|motive power]] input. He considers devices by [[James Watt]], Professor [[James Thomson (engineer)|James Thomson]], [[Fleeming Jenkin]], [[William Thomson, 1st Baron Kelvin|William Thomson]], [[Léon Foucault]] and [[Carl Wilhelm Siemens]] (a liquid governor).{{or|date=October 2025}}

===Natural selection===
In his 1858 paper to the [[Linnean Society of London|Linnean Society]], which led [[Charles Darwin|Darwin]] to publish ''[[On the Origin of Species]]'',{{editorializing|date=October 2025}}{{cn|date=October 2025}} [[Alfred Russel Wallace]] used governors as a metaphor for the [[Evolution|evolutionary principle]]:<blockquote>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.<ref>For a presentation that includes a transcript of the full Wallage essay, "On the Tendency of Varieties to Depart Indefinitely From the Original Type", including this quotation, see {{cite web | author = Beccaloni, George | date = 2008-06-10 | title = The 1858 Darwin-Wallace Paper | work = The Alfred Russel Wallace Website (WallaceFund.myspecies.info) | url = https://wallacefund.myspecies.info/content/1858-darwin-wallace-paper | access-date = 27 October 2025}} Emeritus professor Charles H. Smith presents the following as PDF format of [https://people.wku.edu/charles.smith/essays/Wallace_On_the_Tendency_of_Varieties_to_Depart_Indefinitely_from_the_Original_Type.pdf the same essay], accessed 27 October 2025.</ref></blockquote>

The [[Cybernetics|cybernetician]] and anthropologist [[Gregory Bateson]] thought highly of Wallace's analogy,{{editorializing|date=October 2025}}{{cn|date=October 2025}}<!--THis opinion not in Smith.--> and discussed the topic in his ''[[Mind and Nature: A Necessary Unity]]'' (1979),<ref name="Unfinished Business">{{cite journal | author = Smith, Charles H. | date = 21 December 2004 | title = Wallace's Unfinished Business: The "Other Man" in Evolutionary Theory | format = essays and commentaries | journal = Complexity | volume = 10 | issue = 2 | pages = 25–32 | location = New York, NY | publisher = John Wiley & Sons | url = https://onlinelibrary.wiley.com/doi/pdf/10.1002/cplx.20062 | access-date = 27 October 2025 | doi = 10.1002/cplx.20062 | bibcode = 2004Cmplx..10b..25S }} For the author's posting of the same, see [https://people.wku.edu/charles.smith/essays/UNFIN.htm this link], accessed 27 October 2025.</ref> and other scholars have continued to explore the connection between natural selection and [[systems theory]].{{weasel words inline|date=October 2025}}{{citation needed|date=October 2025}}

==Culture==
{{multiple issues|section = yes|
{{refimprove section|date=October 2025}}
{{original research|section|date=October 2025}}
}}

[[File:Governor Memorial to Boulton and Watt (3549047844).jpg|thumb|right|upright|A memorial to Boulton and Watt industrial design, of a design, inspired by it, in [[Smethwick|Smethwick, England]]<ref name = NoszlopyWaterhouse_Smethwick/>]]
The following are source-derived descriptions of cultural representations of centrifugal governors. A statue inspired by the Boulton and Watt governor design stands in [[Smethwick]], in the [[England|English]] [[West Midlands (county)|West Midlands]].<ref name = NoszlopyWaterhouse_Smethwick>{{cite book | author = Noszlopy, George Thomas & Waterhouse, Fiona | date = 2005 | title = Public Sculpture of Staffordshire and the Black Country | chapter = Smethwick | volume = 9 | series = Public Sculpture of Britain | edition = illustrated | location = Liverpool, England | publisher = Liverpool University Press | page = 119f | isbn = 9780853239895 | chapter-url = https://books.google.com/books?id=RbfVkHMTC0cC&pg=PA119 | access-date = 27 October 2025}}</ref> A centrifugal governor is part of the city seal and flag of [[Manchester, New Hampshire]] in the U.S. (where a 2017 effort to change the design was rejected by voters).<ref>{{cite web | author = Brooks, David | date =  November 7, 2017 | title = Manchester City Flag Celebrates One of the Coolest Inventions from the Industrial Revolution—Happily, They Won't Change It | format = Granite Geek blog | work = [[Concord Monitor]] (concordmonitor.com) | url = https://granitegeek.concordmonitor.com/2017/11/07/manchester-city-flag-celebrates-one-coolest-inventions-industrial-revolution-want-change/ | access-date = 27 October 2025}}</ref> A centrifugal governor—described as an 18th century industrial invention—features in Liu Cixin's science fiction novel, [[Death's End]] (from the [[Remembrance of Earth's Past|''Three-Body'' series)]],<ref>{{Cite AV media |people = Liu, Cixin (author); Liu, David (translator); Ochlan, P. J. (narrator)| orig-date = 2010 | date = 2016 | title=Death's End | chapter = Part III. Broadcast Era, Year 7 / Yun Tianming's Fairy Tales | format = unabrodged audiobook | time = 10:14 (in chapter) | url = https://www.audible.com/pd/Deaths-End-Audiobook/B01LW7OXWP | access-date = 27 October 2025 | url-access = subscription}} Alternatively, see [https://www.worldcat.org/title/936360629 the book format], {{isbn|9780765377104}}, {{oclc|936360629}}.{{full|date=October 2025}}{{page needed|date=October 2025}}</ref>{{primary source inline|date=October 2025}} where it is used as a metaphor.{{cn|date=October 2025}}<!-- for [[Speed of light|"constant speed" (the speed of light)]]-->{{original research inline|certain=true | reason=Per [[WP:PRIMARY]] and [[WP:OR]], editor interpretation of primary source unsupported by a secondary violates WP policy.|date=October 2025}}<!--Please don't add personal interpretations from primary sources! Doing so violates [WP:PRIMARY]] and [[WP:OR]].--> 

A stylized centrifugal governor is part of the coat of arms of the [[Swedish Work Environment Authority]].{{says who|date=October 2025}}{{cn|date=October 2025}}
<!--Please add no further statements if not based on presented citations. Doing so violates multiple WP policites and guidelines.-->

==See also==
* [[Cataract (beam engine)]]
* [[Centrifugal switch]]
* [[Hit and miss engine]]

==References==
{{Reflist}}

==External links==
* {{Commons category inline|Centrifugal governors}}

{{Steam engine configurations}}
{{Authority control}}

{{DEFAULTSORT:Centrifugal Governor}}
[[Category: Dutch inventions]]
[[Category:Inventions by Christiaan Huygens]]
[[Category:Steam engine governors]]
[[Category:Scottish inventions]]
[[Category:British inventions]]
[[Category:Mechanical power control]]
[[Category:Mechanisms (engineering)]]
[[Category:Control devices]]
[[Category:Rotating machines]]
[[Category:Cybernetics]]