The class GEA was a 4-8-2+2-8-4 “Double Mountain” Garratt designed by M.M. Loubser for freight traffic on light branch lines directly after World War II. It was a successor of the class GE 2-8-2+2-8-2 “Double Mikado” where the leading axles had been replaced by two-axle bogies, mainly to carry the weight of larger supplies. Another prominent difference were the streamlined water tank and coal bunker of the GEA. Other differences included bar frames and Timken roller bearings on the leading and trailing axles. 

The boiler of the GEA had the same external dimensions as the one of the GE. But it had a round-topped firebox, a larger superheater and a higher pressure. Although the grate had an area of 51.3 square feet or 4.8 square metres, it was the last Garratt in South Africa without a stoker. With a diameter of 18.5 inches and a stroke of 26 inches, the cylinders were larger than those of the predecessor. With 50 locomotives, this was the largest Garratt order that Beyer, Peacock had received.

After some years in service, the front water tanks of some class members were modified without changing the capacity. This reduced the adhesive weight by more than three tons, but did not reduce the maximum axle load of 15 tons. Some had their coal bunkers extended at the top and were designated GEAM. The last ones were withdrawn in 1976 and after that, six were used by industrial operators. Three have been preserved, all of which are being owned by the Transnet Heritage Foundation.