London & Birmingham 2-2-0 Locomotives in Great_Britain

Class Bury (Locobase 653)

Data confirmed and supplemented by Alexandre Louis Deghilage, Origine de la Locomotive (Paris: Imprierie A Broise et Courtier, 1886), p. 35; and Edward Bury, "On the Locomotive Engines of the London and Birmingham Railway"- read read 17 March 1840, Transactions of the Institution of Civil Engineers, Volume 3, Part IV [4] (), pp. 305-341.

Bury's firebox was the unusual characteristic of this locomotive, which for a time competed with Stephenson's designs. It was cylindrical and D-shaped in cross-section where it joined the horizontal boiler. The hemispherical dome over the firebox collected the steam. Bury used a bar frame with cylinders mounted in their usual location inside and driving through a crank axle.

Bury's 1840 report on the L&B explained his use of a single frame member on each side, and thus not including two middle supports for the driving axle. He contended that the use of outside frames led to requiring additional framing inside required the use of six bearings through which the six-foot crank axle would have to pass. "[I]t is well known to practical men, that it is impossible to key so many bearings prefectly true, and to maintain them so, when the engine is working." (Bury's detailed argument against double framing appears on pages 311-312.)

The diameter of the firebox limited the possible size of the grate and these engines never had much growth potential, although the first examples could pull 57.5 tons at 23 mph (37 kph). Although strong, Hollingsworth (1982) points out, a spherical dome can only offer a firebox as long as it is wide and that was very soon too narrow for traffic demands.

Bury stuck with the four-wheel 2-2-0 arrangement longer than most other builders. Ultimately the need for bigger heating surface areas and greater boiler capacity led the singles-designers to add a trailing axle. Nevertheless, there were advantages to the small size, Hollingsworth claimed::"The were cheap to build and reliable in service." Also, he notes that labor was cheap, so double-,triple-, or even quadruple-heading a train didn't raise operating costs that much.

58 of these locomotives were supplied to the L&B from 1837 to 1841. A later L&B class (the Comet) had 6 wheels in a 2-2-2 arrangement.