Editing GWR 2900 Class (section)

===No. 100===
[[File:Prototype 4-6-0 No.100.jpg|thumb|left|No. 100 as built in 1902]]
The first prototype was completed at the [[Swindon Works]] of the GWR (Lot 132) in February 1902.<ref name=RCTS1>{{harvnb|le Fleming|1953 |p=H22}}</ref> It was numbered 100 and in June 1902 was named ''Dean'' (later ''William Dean'') to mark the latter's retirement. The new design incorporated all of Churchward's current ideas including a domeless [[fire-tube boiler|parallel boiler]], raised [[Belpaire firebox]], {{convert|19|in|cm|1|abbr=on}} diameter outside cylinders with {{convert|30|in|cm|1|abbr=on}} piston stroke, and boiler pressure of {{convert|200|psi|MPa|2|abbr=on|lk=on}}.<ref name=Nock12>{{harvnb |Nock |1983b |p=12}}</ref> The piston valves were driven by rocking levers actuated by the expansion link of [[Stephenson valve gear]] – this particular design was only used on No. 100.<ref name=Nock21>{{harvnb |Nock |1983b |p=21}}</ref> The parallel boiler was later replaced with a [[fire-tube boiler#taper boiler|taper boiler]], and then the first [[superheater|superheated]] taper boiler in 1910. 

Churchward had studied American boiler design, but he was also later influenced by [[Continental Europe|continental]] practice in efficient motion design. A [[Compound locomotive#De Glehn|de Glehn]] [[4-4-2 (locomotive)|4-4-2]] compound engine was ordered from the [[Société Alsacienne de Constructions Mécaniques]] (SACM) for comparative trials on the GWR.<ref name=GWS29xxOvw>[http://www.greatwestern.org.uk/m_in_snt.htm Great Western Society – GW 2900 Class overview] (Accessed 26 April 2009)</ref> According to E.C. Poultney, No. 100 was the first 4-6-0 locomotive to have high enough boiler capacity and steam ports large enough to handle the steam flow required by large cylinders: "The engine probably influenced to a large extent the use made of engines of the 4-6-0 type".<ref name=Poulteney1>{{harvnb|Poultney|1952 |p=47-7}}</ref> No.100 was renumbered 2900 in 1912, and was withdrawn from service in 1932.