After the single 2-6-2+2-6-2 Modified Fairlie of class FC of the South African Railways, Colonel F.R. Collins specified a somewhat heavier variant that was again to be built by North British. The four locomotives were delivered in 1925 and were called class FD. They had direct competition from the class GD Garratt that had the same wheel arrangement.

In service it was found that the long rigid frame produced some problems. These included huge side overhangs when running through curves and oscillations of the water and coal tanks at speed. Also the pivot bearings had to support considerably higher weights due to the supplies being on the main frame. So ultimately the GD Garratts were more successful with 14 built. All FD locomotives were scrapped in 1949.

The South African Railways were looking for a powerful locomotive that could also be used on branch lines and that would be suitable for mixed service at a higher speed. Since at that time only articulated locomotives were to be procured and the required speed required leading bogies, the choice of wheel arrangement fell on the “Double Pacific” for the first time for the SAR, i.e. 4-6-2+2-6-4T.

The specifications were drawn up by Colonel F. R. Collins and sent to Hanomag in Germany, where 37 engines were made in 1927. In 1928, 18 more followed from Henschel and ten from Maffei. This made it the largest number of Garratts built for the SAR until 1953 when the GMA was introduced.

The origin of the locomotive could be seen from the sloped side walls of the driver's cab at the height of the windows. As the first South African Garratt, it had a bar frame that was now established in Germany. The chassis allowed a speed of 80 km/h, but the bearings of the trailing axles often overheated. The solution was to no longer store these axles in an inside but in an outside frame.

As planned, the locomotives were used in front of passenger and freight trains and on branch and main lines. The operational area of most locomotives was in Natal. A higher axle load was permitted on the line from Johannesburg to Mafeking, so that the quantity of coal was increased from 10 long tons to 11 long tons 10 cwt.

Four locomotives were sold to Mozambique as early as 1950, but the remaining machines remained in the SAR's inventory until 1972. At this point, however, not all of them were actively used and it only took until 1979 for the last remaining ones to be scrapped. In the meantime some had been sold to mine operators, most of them to the Enyati Railway. Some of these had received an air brake powered by a diesel-powered compressor. Two examples survive today and a third is being restored.

The class MH of the South African Railways consisted of five 2-6-6-2 Mallets built in 1915 for coal traffic on the line between Witbank and Germiston in Transvaal. There they complemented the class MJ 2-6-6-0 Mallets which had been in service just for a year. Designed by D.A. Hendrie, their parts were manufactured by North British and assembled in the Salvokop shops in Pretoria.

They were superheated from the start, had a round-topped firebox and were initially set for a pressure of 200 psi, which was later reduced to 180 psi. When delivered, they were the biggest and most powerful locomotives which had ever been built for cape gauge. On an incline of 1.05 percent, they were rated for 500 tons. Although they were outperformed by the class GA Garratts delivered from 1920, they remained in service until 1940.