[[File:37906KR.jpg|400px|thumb|right|37906 standing at Kidderminster, 9 July 2011]]
37906 is a '''British Rail Class 37 diesel locomotive 37906''' was built in 1963 and rebuilt with an experimental engine and generator combination in 1987. It was resident on the SVR for several years in the 2000s, leaving the railway in 2014. A summary of the Class 37 can be found on the [[BR Class 37 37308|37308]] page.
==37906 in service==
In 1959, British Railways placed an order with English Electric for a batch of 42 1,750HP [[UIC classification | Co-Co]] diesel-electric locomotives similar to two designs EE were constructing for narrow gauge lines in Africa: the Sudan Government Railways 1000 Class (3ft 6in gauge)<ref>[http://www.12csv.com/main/class/class.php?id=1 English Electric Growl] website, retrieved 1 March 2015.</ref> and the East African Railway 90 Class (metre gauge).<ref>[http://www.12csv.com/main/class/class.php?id=2 English Electric Growl] website, retrived 1 March 2015.</ref> All three classes used EE's 12CSVT diesel engine, and the British Railways examples were very successful. Six further orders resulted in a total of 309 locos entering service with British Railways between 1960 and 1965.<ref>[http://en.wikipedia.org/wiki/British_Rail_Class_37#Building Wikipedia], retrieved 1 March 2015.</ref> 37906 was built at EE's Vulcan Foundry in Newton-le-Willows, works number 3384, and entered service in November 1963 numbered D6906.<ref>[http://www.12csv.com/main/locos/loco.php?id=3384 English Electric Growl] website, retrieved 1 March 2015.</ref> The loco spent most of its working life in South Wales, allocated to Landore Depot in Swansea,<ref>[http://brdatabase.info/locoqry.php?action=locodata&type=D&id=6906&loco=6906 BRDatabase] website, retrieved 1 March 2015.</ref> with short spells at Cardiff Canton, Bristol Bath Road and Plymouth Laira.<ref>[http://www.12csv.com/main/locos/loco.php?id=3384 English Electric Growl] website, retrieved 1 March 2015.</ref> It was renumbered to 37206 in 1973.
In the mid-1980s British Rail was evaluating diesel engines for new locomotive designs such as the proposed but never-built Class 38. In 1986-87, six Class 37 locos were used to trial two potential engines, the Mirrlees MB275T and the Ruston RK270T. 37206 was fitted with the latter engine and a GEC alternator, and like the other five locos received new bogies and additional ballasting to increase its weight to 120 tons. The experimental locomotives became the 37/9 subclass, and 37206 became 37906, the only Class 37/9 to retain the last two digits of its previous number. Along with the rest of subclass 37/9, 37906 returned to South Wales for use on heavy freight work.<ref>[http://en.wikipedia.org/wiki/British_Rail_Class_37#Class_37.2F9 Wikipedia], retrieved 1 March 2015.</ref>