In 1927, the South African Railways placed 37 Class GF Garratt steam locomotives with a 4-6-2+2-6-4 Double Pacific type wheel arrangement in service.

Collins DSO as Chief Mechanical Engineer of the South African Railways (SAR) from 1922 to 1929, articulated locomotives were in great favour in South Africa, to the extent that the Railway Board of the day instructed that non-articulated engines should only be ordered in exceptional circumstances.

[2][3][6] As built, the Class GF had inside bearings in their two-wheeled trailing trucks and considerable trouble was experienced with hot-boxes on these axles.

[1][2] From the establishment of the SAR in 1910, cabside engine number plates were inscribed "SOUTH AFRICAN RAILWAYS" in English only.

After the Official Languages of the Union Act No 8 of 1925 was passed on 8 May 1925, bilingual English and Afrikaans cabside number plates began to appear on locomotives, initially inscribed "SOUTH AFRICAN RAILWAYS" at the top and "SUID AFRIKANSE SPOORWEË" at the bottom, as shown.

[9] The Class GF saw service on many lines in Natal, Transvaal, the Orange Free State and the Eastern Cape.

[1][6][11] By June 1964, Greyville was still allocated nine Class GFs which were used mainly on local passenger and pick-up goods trains.

Most went to the Enyati Railway where, in later years, some were equipped with diesel-driven air brake equipment which was installed in a cage behind the coal bunker, since some of the SAR's air braked coal export block trains originated on the Enyati.

The Central South African Railways (CSAR) introduced Gould knuckle couplers on the rolling stock of its Limited Express and Imperial Mail passenger trains in 1904.