Under the Whyte notation for the classification of steam locomotives, 0-4-0 represents one of the simplest possible types, that with two axles and four coupled wheels, all of which are driven. The wheels on the earliest four-coupled locomotives were connected by a single gear wheel, but from 1825 the wheels were usually connected with coupling rods to form a single driven set.
4-4-0, in the Whyte notation, denotes a steam locomotive with a wheel arrangement of four leading wheels on two axles, four powered and coupled driving wheels on two axles, and no trailing wheels.
Under the Whyte notation for the classification of steam locomotives, 4-2-2 represents the wheel arrangement of four leading wheels on two axles, two powered driving wheels on one axle, and two trailing wheels on one axle.
The Great Western Railway 3800 Class, also known as the County Class, were a class of 4-4-0 steam locomotives for express passenger train work introduced in 1904 in a batch of ten. Two more batches followed in 1906 and 1912 with minor differences. They were designed by George Jackson Churchward, who used standard components to produce a four-coupled version of his Saint Class 4-6-0s.
The Caledonian Railway 812 and 652 Classes were 0-6-0 steam tender locomotives designed by John F. McIntosh for the Caledonian Railway and introduced in 1899. They had the same boiler type as the 721 “Dunalastair” Class 4-4-0s. They could reach speeds of up to 55 mph (89 km/h).
Under the Whyte notation for the classification of steam locomotives, 2-4-0 represents the wheel arrangement of two leading wheels on one axle, four powered and coupled driving wheels on two axles and no trailing wheels. In most of North America it became known as a Porter.
Under the Whyte notation for the classification of steam locomotives, 0-4-2 represents the wheel arrangement with no leading wheels, four powered and coupled driving wheels on two axles and two trailing wheels on one axle. While the first locomotives of this wheel arrangement were tender engines, the configuration was later often used for tank engines, which is noted by adding letter suffixes to the configuration, such as 0-4-2T for a conventional side-tank locomotive, 0-4-2ST for a saddle-tank locomotive, 0-4-2WT for a well-tank locomotive and 0-4-2RT for a rack-equipped tank locomotive.
The London and North Eastern Railway (LNER) Class K4 is a class of 2-6-0 steam locomotives designed by Nigel Gresley for the steep grades of the West Highland Line.
The Glasgow and South Western Railway (G&SWR) 403 Class was a class of 2-6-0 (mogul) steam locomotive designed by Peter Drummond, of which 11 were built in 1915 by the North British Locomotive Company at its Queens Park works. Originally built as the 403 class, as a result of renumbering they became known as the 33 Class in 1916 and then 51 Class in 1919, before passing to the London Midland and Scottish Railway (LMS) on its formation in 1923, where they were given power classification 4F.
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.
The South African Railways Class 21 2-10-4 of 1937 was a class of steam locomotives used in South Africa.
The South African Railways Class 14C 4-8-2 of 1922 was a steam locomotive.
The South African Railways Class GMA 4-8-2+2-8-4 of 1954 is an articulated steam locomotive.
The locomotives of the Highland Railway were used by the Highland Railway to operate its lines in the north of Scotland. The Highland Railway locomotive works was at Lochgorm, Inverness. The works had been built about 1855 by the Inverness and Nairn Railway. The locomotive classes are listed under the names of the railway's Locomotive Superintendents.
The Caledonian Railway 721 Class was a class of 4-4-0 steam locomotives designed by John F. McIntosh for the Caledonian Railway (CR) and introduced in 1896. Taking their name from the estate in Perthshire owned by the Caledonian’s then deputy chairman, J.C.Bunten, all survived to be absorbed by the London, Midland and Scottish Railway (LMS) in 1923 and a few survived into British Railways (BR) ownership in 1948.
The Caledonian Railway 49 Class and 903 Class were 4-6-0 express passenger locomotives designed by John F. McIntosh and built at the Caledonian Railway's own St. Rollox Works in 1903 and 1906 respectively.
The South African Railways Class 14C 4-8-2 of 1919 was a steam locomotive.
The Bridge Stress Committee was appointed in 1923 by the UK Department of Scientific and Industrial Research under Sir Alfred Ewing, to investigate stresses in railway bridges, especially as regards the effects of moving loads. Its report, published in 1928, was very influential in British locomotive design as it enabled larger multi-cylinder locomotive classes.
The Glasgow and South Western Railway (G&SWR) 279 class was a class of 0-6-0 steam locomotive designed by Peter Drummond, of which 15 were built in 1913 by the North British Locomotive Company at its Queen's Park works. Originally built as the 279 class, as a result of renumbering they became known as the 71 class in 1919, before passing to the London Midland and Scottish Railway (LMS) on its formation in 1923, where they were given power classification 4F.
The Highland Railway 'Castle Class' was a class of 4-6-0 locomotives designed in 1900 by Peter Drummond, chief mechanical engineer of the Highland Railway at the time. 19 locomotives were built by Dübs and North British Locomotive Co. until 1917, and the last were withdrawn from service in 1947.
