Great Western Railway Power and Weight Classification
A surviving GWR 2884 steam locomotive with a power rating of a black “E” on the blue weight classification disc above the number plate. A white "X" can be seen between the disc and the number plate, which affects how the power class is interpreted. (West Somerset Railway)
Since 1920, the cabins of Great Western Railway (GWR) steam locomotives have been labelled on a coloured disc, allowing staff to quickly assess the capabilities of locomotives without having to check datasheets. The letter designated the power rating, and the coloured disc indicated the weight limit. This system continued even after the GWR became the Western Region of British Railways.
from mid-1919 it began to appear on the locomotives themselves. The weight limit was shown as a coloured disc, and the power class by a capital letter on the disc. At first it was painted high on the side of the cockpit but, during the Second World War in darkened measures to ensure that personnel had to be careful with the use of light at night, the disc and letter were moved down to a position just above the engine cabside number plate to make them more visible. When locomotives were loaned to the GWR by other railways during World War II, they were also given a GWR power and weight classification so that GWR locomotive design personnel could select the most suitable engine for the task without having to learn an unfamiliar system.
History
Two diesel-hydraulic locomotives of the Western region; D7072 (left) is class 35 with a red route restriction disc; D6343 (right) is Class 22 and has a yellow disc. Both discs are numbered on the sides. (Max Battens)
A surviving GWR 4500 class steam locomotive with a "C" power rating on a yellow route restriction disc on the upper side of the cab. (Philip Halling)
On July 1, 1905, the Great Western Railway (GWR) introduced a designation system for both transport capabilities and weight restrictions that applied to different classes of locomotives. Initially, this was only used in logbooks, but
The GWR was nationalized in 1948, becoming the Western Region of British Railways and in 1949, BR decided to adopt the London, Midland and Scottish Railways (LMS) capacity classification system for all locomotives. Despite this, the use of a letter to denote power classification continued to be used on former GWR steam locomotives, as did a coloured disc for weight classification; both continued until the end of steam traction on the Western Region in 1965. Certain ex-LMS and BR Standard steam locomotives dedicated to the Western Region were provided with GWR type route classification discs, usually without
January/February 2021
GREAT WESTERN STAR MAGAZINE
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