The success of the five Class NG G11 Garratt narrow-gauge locomotives which had been placed in service on the Avontuurline in the Langkloof and the Stuartstown line in Natal between 1919 and 1925 led to the decision by Col F.R. Collins DSO, Chief Mechanical Engineer of the South African Railways, to acquire a smaller Garratt type for two new light-rail narrow-gauge branch lines which were completed in 1926. In 1927, orders were placed with Beyer, Peacock and Company for the design and construction of two lightweight narrow-gauge Garratt locomotives with a Double Prairie type wheel arrangement. Beyer, Peacock sub-contracted their construction and the two locomotives were delivered by the Belgian locomotive builders Société Franco-Belge in November 1927. They were allocated separate works numbers by Beyer, Peacock as well as Franco-Belge and were numbered NG56 and NG57 upon delivery.
Characteristics
The locomotives were superheated, with outside plate frames, Walschaerts valve gear, inclined cylinders, piston valves and round-topped fireboxes. Designed for light rail, their lightness of construction made them popular with the fitters who had to maintain them.
Classification
The system of grouping narrow-gauge locomotives into classes was only adopted by the SAR somewhere between 1928 and 1930 and, at that point, these two locomotives were designated Class NG G12, with the letters "NG" indicating narrow gauge and the "G" prefix to the classification number identifying it as a Garratt locomotive.
Service
The Class NG G12 was obtained for use on the new narrow-gauge lines from Fort Beaufort to Seymour and from Upington to Kakamas which had been completed in 1926, since it had become obvious that the Class NG6 Lawleys which had been used during the construction of these lines would not be able to cope with the expected daily traffic once the lines were in full operation. Upon arrival, the two locomotives were first put to work in South West Africa for a trial period, after which no. NG56 was assigned to Upington and no. NG57 to Fort Beaufort. While they both mostly remained with their assigned depots, they were at times temporarily assigned to narrow-gauge branch lines in other areas of the country to assist with seasonal demands on those branches. In 1940, when the Seymour branch was regauged to Cape gauge, no. NG57 was also assigned to the Kakamas branch. Both remained there until 1949, when the Kakamas line was also widened to Cape gauge and they were returned to South West Africa for a brief period. From there, no. NG56 was allocated to Port Shepstone in Natal and no. NG57 to Humewood Road in Port Elizabeth, where they remained until both were withdrawn from service in 1952. Both locomotives were subsequently sold to the Rustenburg Platinum Mines, no. NG56 in 1952 and no. NG57 in 1953, where they were renumbered 5 and 6 respectively. They were both scrapped in 1959.
