4-4-0

Schematic of 4-4-0 steam locomotive wheel arrangement. (Front of locomotive at left)

Under the Whyte notation for the classification of steam locomotives, 4-4-0 represents the wheel arrangement of four leading wheels on one axle, four powered and coupled driving wheels, and no trailing wheels. This arrangement was often named American, especially in the United States, but the type subsequently also became popular in the United Kingdom, where large numbers were produced. They can pull half a dozen passenger cars or less in passenger service.

1836 Patent drawing of the first 4-4-0 locomotive

Almost every major railroad that operated in North America in the first half of the 19th century owned and operated locomotives of this type. The first use of the name American to describe locomotives of this wheel arrangement was made by Railroad Gazette in April 1872. Prior to that, this wheel arrangement was known as a standard or eight-wheeler.

This locomotive type was so successful on railroads in the United States of America that many earlier 4-2-0 and 2-4-0 locomotives were rebuilt as 4-4-0s by the middle of the 19th century.

Several 4-4-0 tank locomotives were built, but the vast majority of locomotives of this wheel arrangement were tender engines.

Australia

South Australian Railways S Class No. 17 at Tailem Bend in 1952

The first 4-4-0s appeared in South Australia in 1859. From that initial order for two locomotives, the numbers of this wheel arrangement multiplied and eventually appeared in most of the Australian colonies. Tender, tank and saddle tank versions, varying in size from small engines to express passenger racers with 6 feet 6 inches (1,981 millimetres) driving wheels, worked in Victoria, New South Wales, Western Australia and Tasmania on 3 ft 6 in (1,067 mm) gauge, 4 ft 8+1⁄2 in (1,435 mm) standard gauge and 5 ft 3 in (1,600 mm) gauge.

The locomotives originally from British builders such as Dübs & Company and Beyer, Peacock & Company, however, from late 1870's into the 1880s, railways also bought locomotives from American builders, mostly from Baldwin, as well as a few examples bought from the Rogers Locomotive & Machine Works in New Jersey. From the 1880s onward, local firms such as James Martin & Co. in Gawler, South Australia, and the Phoenix Foundry in Ballarat, Victoria would also build examples. In New South Wales and Victoria, the 4-4-0 ruled the rails for mainline passenger services until the early 1900s. In Western Australia, some were later converted to 4-4-2s.

Finland

Finnish Class A5 No. 58 in the Finnish Railway Museum

In Finland, the 4-4-0 was represented by the Classes A1, A2, A3, A4, A5, A6 and A7.

The Class A4 was a class of nine locomotives, built in 1872 and 1873 by the Baldwin Locomotive Works for use on the Hanko–Hyvinkää railway.

The Finnish Steam Locomotive Class A5 was a class of only two locomotives, built in 1874 and 1875 by the Finnish State Railroad's workshops in Helsinki. One of them is preserved at the Finnish Railway Museum.

New Zealand

NZR LA Class No.  205 in 1897

The NZR LA class tank locomotives of 1887 were built in Britain by Nasmyth, Wilson & Company in 1887 for the New Zealand Midland Railway Company. They were taken over by the New Zealand Railways Department in 1900, when the government acquired the incomplete Midland line.

United States

Replica of Central Pacific No. 60 'Jupiter' an American 4-4-0

Five years after new locomotive construction had begun at the West Point Foundry in the United States with the 0-4-0 Best Friend of Charleston in 1831, the first 4-4-0 locomotive was designed by Henry R. Campbell, at the time the chief engineer for the Philadelphia, Germantown and Norristown Railway. Campbell received a patent for the design in February 1836 and soon set to work building the first 4-4-0.

At the time, Campbell's 4-4-0 was a giant among locomotives. Its cylinders had a 14-inch (360 mm) bore with a 16-inch (410 mm) piston stroke, it boasted 54-inch (1,400 mm) diameter driving wheels, could maintain 90 pounds per square inch (620 kPa) of steam pressure and weighed 12 short tons (11 t). Campbell's locomotive was estimated to be able to pull a train of 450 short tons (410 t) at 15 miles per hour (24 km/h) on level track, outperforming the strongest of Baldwin's 4-2-0s in tractive effort by about 63%. However, the frame and driving gear of his locomotive proved to be too rigid for the railroads of the time, which caused Campbell's prototype to be derailment prone. The most obvious cause was the lack of a weight equalizing system for the drivers.

By 1910, the 4-4-0 was considered obsolete being replaced by Mikados, Pacifics and other larger engines, although they continued to serve to an extent into the 1950s. The last 4-4-0 to be built was a diminutive Baldwin product for the United Railways of Yucatan in 1945. Fewer than forty 4-4-0s survive in preservation in the United States, reproductions excluded.