Lap Engine: Difference between revisions

Revision as of 08:01, 13 March 2015

Revision as of 12:17, 13 March 2015

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|alt =

|caption =

|type = [[Watt steam engine|Watt]], [[rotative beam engine|rotative beam]]

|designer = [[James Watt]]

|maker = [[Boulton and Watt]]

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|working = No

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The '''''Lap Engine''''' is an early [[beam engine]] of 1788, built by [[James Watt]]. 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" />

== 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" />

=== Parallel motion ===

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=== Sun and planet gear ===

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

{{Details|Sun and planet gear}}

IsThe [[rotative beam engine]] needs a methodmeans ofto convertingconvert [[reciprocating motion]] of the piston and beam to [[rotary motion]]. andThe [[crankshaft]] was usedwell known for centuries before Watt, mostly from its use in themining firstmachinery powered by [[rotativewater beamwheel]]s. However its use for a steam engine was covered by [[James Pickard]]'s patent at this time..<ref >{{Cite book

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

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|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|]]

{{Details|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 ==

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{{Steamsteam engine configurations|state=collapsed}}

[[Category:Preserved beam engines]]

<!-- [[Category:James Watt]] -->

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

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