Great Western Railway Power and Weight Classification

A preserved GWR 2884 Class steam locomotive, showing the power classification as a black letter "E" on a blue weight classification disc, painted above the numberplate. Between the disc and numberplate may be seen a white letter "X", which affects how the power class is interpreted

From 1920, the cab side of Great Western Railway (GWR) steam locomotives bore a letter on a coloured disc, which enabled staff to quickly assess the capabilities of locomotives without the need to check tables of data. The letter showed the power classification, and the coloured disc showed the weight restriction. This system continued after the GWR became the Western Region of British Railways.[1][2]

  1. ^ abc Locomotives 1955, p. 64.
  2. ^ Allcock et al. 1951, pp. 59–60.