2-4-2+2-4-2

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2-4-2+2-4-2 (Double Columbia)
Diagram of one small leading wheel, two large driving wheels joined by a coupling rod, two small trailing wheels, two large driving wheels joined by a coupling rod, and one small leading wheel
Equivalent classifications
UIC class 1B1+1B1, 1’B1’+1’B1’
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[edit]

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.

2-4-2+2-4-2 Garratt production list – All manufacturers[1]
Gauge Railway Numbers Works no. Units Year Builder
1,000 mm (3 ft 3 38 in) metre gauge Leopoldina Railway, Brazil 400-403 6976-6979 4 1943 Beyer, Peacock

Usage[edit]

Brazil[edit]

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 38 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[edit]

  1. ^ a b c Hamilton, Gavin N., The Garratt Locomotive - Garratt Locomotives produced by Beyer, Peacock, retrieved 10 November 2012