4-6-0

4-6-0 (Ten-wheeler)

Front of locomotive at left

Prussian P 8, the most numerous 4-6-0 in the world

Equivalent classifications UIC class 2'C' French class 230 Turkish class 35 Swiss class 3/5 Russian class 2-3-0

First known tank engine version First use 1880 Country Colony of Natal Locomotive NGR Class G Railway Natal Government Railways Designer Kitson and Company Builder Kitson and Company Evolved from 2-6-0T Evolved to 4-6-2T

First known tender engine version First use 1847 Country United States of America Locomotive Chesapeake Railway Philadelphia and Reading Railroad Designer Septimus Norris Builder Norris Locomotive Works Evolved from 4-4-0 Evolved to 4-6-2, 4-8-0 Drawbacks Small firebox

Under the Whyte notation for the classification of steam locomotives by wheel arrangement, 4-6-0 represents the configuration of four leading wheels on two axles in a leading bogie, six powered and coupled driving wheels on three axles and no trailing wheels. In the mid 19th century, this wheel arrangement became the second most popular configuration for new steam locomotives in the United States of America, where this type is commonly referred to as a Ten-wheeler.

During the second half of the nineteenth and first half of the twentieth centuries, the 4-6-0 was constructed in large numbers for passenger and mixed traffic service. A natural extension of the 4-4-0 American wheel arrangement, the four-wheel leading bogie gave good stability at speed and allowed a longer boiler to be supported, while the lack of trailing wheels gave a high adhesive weight.

The primary limitation of the type was the small size of the firebox, which limited power output. In passenger service, it was eventually superseded by the 4-6-2 Pacific type whose trailing truck allowed it to carry a greatly enlarged firebox. For freight service, the addition of a fourth driving axle created the 4-8-0 Mastodon type, which was rare in North America, but became very popular on Cape gauge in Southern Africa.

The 4-6-0T locomotive version was a far less common type. It was used for passenger duties during the first decade of the twentieth century, but was soon superseded by the 4-6-2T Pacific, 4-6-4T Baltic and 2-6-4T Adriatic types, on which larger fire grates were possible. During the First World War, the type was also used on narrow gauge military railways.