- GWR 4000 Class
A Star class locomotive was a particular type of
steam locomotive of theGreat Western Railway . The prototype was an experimental locomotive, "North Star" (originally given number 40), constructed with the 'Atlantic' 4-4-2 wheel arrangement for comparative trials with 4-cylinder compound locomotives of the de Glehn type that had been purchased from France. This established the benefits of the balanced 4 cylinder layout but the designer, George Churchward, decided that he would continue the class with simple steam expansion, and also with the4-6-0 wheel arrangement he had introduced with the 2900 class. As in the de Glehn design, the outer cylinders drove the centredriving axle , the inside pair of cylinders were set well forward and drove the leading driving axle.In the production class (4001 to 4072) there were just two set of
Walschaerts valve gear between the frames, the valves to the outside cylinders being driven by rocking levers.An enlarged version of the design was introduced in 1923, this was the Castle Class locomotive, of which about 170 were constructed, including some rebuilds from the 'Star' class.
One, 4003 Lode Star, survives in preservation as a static, non-working, exhibit.
List of locomotives
External links
* http://www.greatwestern.org.uk/m_in_str.htm
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