In 1925, the South African Railways placed a single Class GG Garratt articulated steam locomotive with a 2-6-2+2-6-2 Double Prairie type wheel arrangement in fast mainline passenger service.

It was designed for the South African Railways (SAR) with large coupled wheels for fast passenger service on mainline duties.

[1][3][4][5][6] At 57 inches (1,448 millimetres) diameter, the Class GG had the largest coupled wheels yet seen on a Garratt locomotive in South Africa.

As a result, the locomotive's tractive effort was inferior to that of the Class 15CA which was introduced on the same line between Touws River and De Aar a year later.

It could handle a load of 1,245 long tons (1,265 tonnes) on 1 in 80 (1¼%) gradients and hauled 340 long tons (345 tonnes) up the 15 miles (24 kilometres) of 1 in 40 (2½%) gradient of the Hex River Railpass in sixty-two minutes without the help of the usual banking locomotive.