Lap Engine: Difference between revisions

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{{Use dmy dates|date=JuneOctober 20112020}}

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{{Infobox historic engine

|name = ''Lap Engine''

|image = File:Science Museum - the 'lap engine' (geograph 3661968).jpg

|image_size =

|alt =

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|collection = [[Science Museum Group]]

|___location = [[Science Museum, London]]

|accession = 1861-461861–46<ref name="Science-Museum-1861-46">{{Cite web

|title=Rotative steam engine by Boulton and Watt, 1788.

|website=Science Museum

|url=http://www.sciencemuseum.org.uk/objects/motive_power/1861-46.aspx

|access-date=13 March 2015

}}</ref>

|archive-date=24 September 2015

|archive-url=https://web.archive.org/web/20150924114903/http://www.sciencemuseum.org.uk/objects/motive_power/1861-46.aspx

|url-status=dead

}}</ref>

|working = No

}}

The '''Lap Engine''' is an earlya [[beam engine]] ofdesigned 1788by [[James Watt]], built by [[JamesBoulton and Watt]] in 1788. It is now preserved at the [[Science Museum, London]].

It is important as both an early example of a beam engine by [[Boulton and Watt]], and also mainly as illustrating an important innovative step in their development for its ability to produce rotary motion.<ref name="Dickinson & Jenkins, 1927" /><ref name="Crowley, Lap Engine" />

The engines name comes from its use in [[Matthew Boulton]]'s [[Soho Manufactory]], where it was used to drive a line of 43 polishing or [[lapping]] machines, used for the [[Birmingham toy industry|production of buttons and buckles]].<ref name="SM, Lap Engine" /><ref name="Hulse, web, Lap Engine" />

== Innovations ==

Watt did not invent the steam engine and there is no single '[[Watt steam engine]]' as such. He developed a number of separate innovations, each of which improved the existing engines of the day, beginning with [[Newcomen atmospheric engine|Newcomen's]]. The Lap Engine of 1788, also the [[Boulton and Watt steam engine (Powerhouse Museum)|Whitbread Brewery engine]] (1785), represent survivors of the first engines to show all of Watt's major improvements in one.<ref name="Crowley, Lap Engine" />

[[File:Thinktank Birmingham - object 1950S00022(1).jpg|thumb|A 1950 model of the engine, now in [[Thinktank, Birmingham Science Museum]] ]]

Watt did not invent the [[steam engine]] and there is no single '[[Watt steam engine]]' as such. He developed a number of separate innovations, each of which improved the existing engines of the day, beginning with [[Newcomen atmospheric engine|Newcomen's]]. The Lap Engine of 1788, also the [[Boulton and Watt steam engine (Powerhouse Museum)|Whitbread Brewery engineEngine]] (1785), represent survivors of the first engines to show all of Watt's major improvements in one.<ref name="Crowley, Lap Engine" />

=== Parallel motion ===

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=== Sun and planet gear ===

[[File:Sun and planet gear science museum.JPG|thumb|The [[Sunsun and planet gear]]]]

{{Details|Sun and planet gear}}

The [[rotative beam engine]] needs a means to convert [[reciprocating motion]] of the piston and beam to [[rotary motion]]. The [[crankshaft]] was well known for centuries before Watt, mostly from its use in mining machinery powered by [[water wheel]]s. However its use for a steam engine was covered by [[James Pickard]]'s patent at this time..<ref >{{Cite book

|title=Catalogue of the Mechanical Engineering Collection in the Science Division of the Victoria and Albert Museum, South Kensington

|publisher=Read Books

|year=2007

|url=httphttps://books.google.com/books?id=95MUkfFgBFwC&pg=PA35

|isbn=978-1-4067-8053-6

|page=35

}}</ref> Watt was unwilling to pay a license fee to use the [[crank (mechanism)|crank]] and so sought an alternative. The sun and planet gear was invented by another [[Scottish people|Scottish]] engineer, [[William Murdoch]], an employee of [[Boulton and Watt]]. Watt patented it in October 1781.

The sun and planet gear is a simple [[epicyclic gear]]. The planet is attached rigidly to the end of the [[connecting rod]], hung from the beam. As it rotates it applies a torque to the sun gear, just as for a crank, and so causes it to rotate. As the two gears also rotate relative to each other, like conventional gearwheels, this has the effect of giving the sun gear a further rotation. The sun, and the output crankshaft, thus rotates twice for every piston cycle of the engine, twice as fast as with a conventional crank. Beam engines were slow-moving and the output shafts driven by the Lap Engine were fast-moving, so this was an advantage.

{{clear right}}

=== Centrifugal governor ===

[[File:Boulton and Watt centrifugal governor-MJ.jpg|thumb|upright|The Watt-type [[centrifugal governor]] at the Science Museum, London.]]

{{Details|Centrifugal governor}}

According to the Science Museum, it was the first steam engine to be fitted with a [[centrifugal governor]].<ref name="Science-Museum-1861-46"/>{{efn|The earlier [[Whitbread Engine]] of 1785, and the 1786 engine at the [[National Museum of Scotland]] also have a centrifugal governor.}}

{{clear right}}

== History ==

{{Empty section|date=March 2015}}

== Preservation ==

{{Empty section|date=March 2015}}

== See also ==

* [[Boulton and Watt steam engine (Powerhouse Museum)|Whitbread Brewery engine]], a similar engine of 1785, now preserved at the [[Powerhouse Museum]] in [[Sydney]], Australia.

== References Notes==

{{Commons category|The Lap Engine}}

{{notelist}}

== References ==

{{Reflist|colwidth=35em|refs=

<ref name="SM, Lap Engine" >{{Cite web

|title=Rotative steam engine by Boulton and Watt, 1788.

|website=Science Museum

|url=https://collection.sciencemuseumgroup.org.uk/objects/co50948/rotative-steam-engine-by-boulton-and-watt-1788-beam-engines

|url=http://www.sciencemuseum.org.uk/online_science/explore_our_collections/objects/index/smxg-50948

}}</ref>

<ref name="Hulse, web, Lap Engine" >{{Cite web

|title=The Lap Engine

|author=David Hulse

|url=http://www.davidhulse.co.uk/543/The-Lap-Engine/

}}</ref>

<!--<ref name="Hulse, Rotary, Lap Engine" >{{Cite book

|title=The Development of Rotary Motion by Steam Power

|first=David |last=Hulse

|chapter=The Lap Engine

|publisher=TEE Publishing

|isbn=1857611195

|year=2001

|url=http://www.davidhulse.co.uk/551/David-Hulse---About-My-Books/

}}</ref>-->

<ref name="Dickinson & Jenkins, 1927" >{{cite book

|last=Dickinson |first=H.W.

|last2=Jenkins |first2=R.

|title=James Watt and the Steam Engine

|origyearorig-year=1927

|year=1981

|publisher=Moorland Publishing

|isbn=0-903485-92-3

|ref={{harvid|Dickinson|Jenkins|1927}}

}}</ref>

|pages=

}}</ref>

<ref name="Crowley, Lap Engine" >{{Cite book

|last=Crowley |first=T.E.

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|year=1982

|isbn=0-906831-02-4

|}}</ref=harv>

}}

|pages=

}}</ref>

== Further reading ==

* {{Cite magazine

|magazine=[[Model Engineer]]

|volume=146 |issue=3626

|title=Watt's Lap Engine

|date=1 February 1980

}}

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[[Category:Steam engines in the Science Museum, London]]

[[Category:Preserved stationary steam engines]]

[[Category:1788 in England]]

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[[Category:1788 in science]]

[[Category:Industrial Revolution]]

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[[Category:History of the steam engine]]

[[Category:James Watt]]