Lap Engine: Difference between revisions

Revision as of 12:40, 13 March 2015

Revision as of 08:55, 14 March 2015

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|collection = [[Science Museum Group]]

|___location = [[Science Museum, London]]

|accession = 1861-46<ref >{{Cite web

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

|website=Science Museum

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

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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}}

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{{clear right}}

== History ==

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== Preservation ==

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== See also ==

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{{steam engine configurations|state=collapsed}}

{{Use dmy dates|date=June 2011}}

[[Category:Preserved beam engines]]

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

{{Use dmy dates|date=June 2011}}

{{engineering-stub}}