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 In passenger service, it was eventually superseded by the 4-6-2 Pacific type whose trailing truck allowed it to carry a greatly enlarged firebox.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 It was used for passenger duties during the first decade of the twentieth century, but was soon superseded by the 4-6-2T Pacific, 4-6-4T Baltic and 2-6-4T Adriatic types, on which larger fire grates were possible.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.
In 1907, five 6th Class locomotives of the Cape Government Railways were sold to the 3 ft 6 in (1,067 mm) Benguela Railway (CFB). These included one of the Dübs-built locomotives of 1897 and two each of the Neilson and Company and Neilson, Reid and Company-built locomotives of 1897 and 1898. (Also see South Africa - Cape gauge)
In the mid-1930s, in order to ease maintenance, modifications were made to the running boards and brake gear of the CFB locomotives. The former involved mounting the running boards higher, thereby getting rid of the driving wheel fairings. This gave the locomotives a much more American rather than British appearance.
In April 1951, three Class NG9 locomotives were purchased from the South African Railways for the Caminhos de Ferro de Moçâmedes (CFM). They were placed in service on the Ramal da Chibía, a 600 mm (1 ft 11 5⁄8 in) gauge branch line across 116 kilometres (72 miles) from Sá da Bandeira to Chiange. The locomotives were observed dumped at the Sá da Bandeira shops by 1969 and the branch line itself was closed in 1970. (Also see South Africa - Narrow gauge)
In 1897, three Class 6 4-6-0 locomotives were ordered by the Cape Government Railways (CGR) from Neilson and Company for use on the new Vryburg to Bulawayo line of the fledgling Bechuanaland Railway Company (BR). The line through Bechuanaland Protectorate was still under construction and was operated by the CGR on behalf of the BR at the time. The locomotives were eventually returned to the CGR.