Under the Whyte notation for the classification of steam locomotives by wheel arrangement, the 2-4-2+2-4-2 is a Garrattarticulated locomotive. The wheel arrangement is effectively two 2-4-2 locomotives operating back to back, with the boiler and cab suspended between the two power units. Each power unit has a single pair of leading wheels in a leading truck, followed by two coupled pairs of driving wheels, with a single pair of trailing wheels in a trailing truck. Since the 2-4-2 type is sometimes known as a Columbia, the corresponding Garratt type could be referred to as a Double Columbia.
This was the rarest of all Garratt types, with only one class of four locomotives constructed to this wheel arrangement. It most likely evolved from the 2-4-0+0-4-2 Double Porter Garratt, with the trailing wheels added on each engine unit to improve stability at speed.
2-4-2+2-4-2 Garratt production list – All manufacturers
All four 2-4-2+2-4-2 locomotives were built in 1943 by Beyer, Peacock and Company for the 1,000 mm (3 ft 33⁄8 in) metre gauge Leopoldina Railway in Brazil. The locomotives were allocated engine numbers in the range from 400 to 403 on that system.