During 1946 and 1947, the South African Railways placed fifty Class GEA Garratt articulated steam locomotives with a 4-8-2+2-8-4 Double Mountain type wheel arrangement in service.

The inner firebox was of steel instead of copper and it had a hopper type ashpan, fitted with an efficient arrangement of drench pipes.

The boiler pressure was 20 pounds per square inch (138 kilopascals) higher than that of the Class GE and it had a larger superheater area with 36 elements and incorporating a multiple valve regulator.

[2] The outer bogies had two-pin swing links and laminated side control springs which provided for a total side-play of 7 inches (178 millimetres).

The inner bissel trucks were of the radial-arm type with helical spring side control and a total side-play of 4 inches (102 millimetres).

Sliding louvres in the cab sides provided adequate weather protection while the lookout had hinged adjustable glass windscreens.

[1][4][6] In the Western Cape, wheatland fires caused by locomotives were a huge problem for farmers as well as for the SAR who had to pay out the claims.

4009 the tubes fed the exhaust forward to the outlet above the front end of the Garratt's water bunker, which led to the engine being nicknamed Renoster (rhinoceros).

[4][7] The locomotives were designed for goods traffic on light 60 pounds per yard (30 kilograms per metre) rail on branch lines.

They started their service lives working goods traffic on the lines from Johannesburg to Zeerust in the Western Transvaal.

Some were later transferred to Natal to work on the North Coast line, based at Stanger and Empangeni, and on the Eshowe and Nkwalini branches.

They also worked on the Franklin branch and the Overberg line from Cape Town across Sir Lowry's Pass to Caledon.