2-4-2+2-4-2

2-4-2+2-4-2 (Double Columbia)

Equivalent classifications UIC class 1B1+1B1 French class 121+121 Turkish class 24+24 Swiss class 2/4+2/4, 4/8 from the 1920s Russian class 1-2-1+1-2-1

First known tank engine version First use 1943 Country Brazil Railway Leopoldina Railway Designer Beyer, Peacock and Company Builder Beyer, Peacock and Company Evolved from 2-4-0+0-4-2

Under the Whyte notation for the classification of steam locomotives by wheel arrangement, the 2-4-2+2-4-2 is a Garratt articulated 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.

Overview

This was the rarest of all Garratt types, with only one class of four locomotives constructed to this wheel arrangement.^[1] 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.

Usage

Brazil

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 3 ³⁄₈ in) metre gauge Leopoldina Railway in Brazil. The locomotives were allocated engine numbers in the range from 400 to 403 on that system.^[1]

References

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