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4-4-2+2-4-4

Locomotive wheel arrangement

Field	Value
name	4-4-2+2-4-4 (Double Atlantic)
image	WheelArrangement 4-4-2+2-4-4.svg
alt	Diagram of two small leading wheels, two large driving wheels joined by a coupling rod, two small trailing wheels, two large driving wheels joined by a coupling rod, and two small leading wheels
UIC/Germany/Italy	2B1+1B2
French/Spanish	221+122
Turkish	25+25
Swiss	2/5+2/5, 4/10 from the 1920s
Russian	2-2-1+1-2-2
date	1912
country	Australia
locomotive	TGR M class
railway	Tasmanian Government Railways
designer	Beyer, Peacock & Company
builder	Beyer, Peacock & Company

| UIC/Germany/Italy= 2B1+1B2 | French/Spanish = 221+122

Under the Whyte notation for the classification of steam locomotives by wheel arrangement, a 4-4-2+2-4-4 is a Garratt articulated locomotive. The wheel arrangement is effectively two 4-4-2 locomotives operating back to back, with each power unit having four leading wheels on two axles in a leading bogie, four powered and coupled driving wheels on two axles, and two trailing wheels on one axle in a trailing truck. Since the 4-4-2 type is usually known as an Atlantic, the corresponding Garratt type is often referred to as a Double Atlantic.

Overview

The 4-4-2+2-4-4 was not a common Garratt wheel arrangement. Only ten were built, all by Beyer, Peacock & Company, the owner of the Garratt patent.

Railway	Class	Works no.	Units	Year	Builder
Tasmanian Government Railways	M	5523–5524	2	1912	Beyer, Peacock & Company
Entre Ríos Railway, Argentina		6360–6364	5	1927	Beyer, Peacock & Company
Argentine North Eastern Railway		6645–6647	3	1930	Beyer, Peacock & Company

Usage

Argentina

Eight locomotives were built for Argentina to run on .

Five were built for the Entre Ríos Railway in 1927.
Another three were built for the Argentine North Eastern Railway in 1930.

After nationalization in 1948, all these locomotives were rostered on the General Urquiza Railway.

Australia

The first Garratt locomotives to be built to the 4-4-2+2-4-4 wheel arrangement were a pair of M class passenger locomotives for the gauge Tasmanian Government Railways in Australia in 1912. They were acquired to haul express passenger trains between Launceston and Hobart.

The two M class engines were the only eight-cylinder Garratt locomotives in the world. They were difficult to maintain and, despite their haulage abilities and speed, both were withdrawn from service some time after the arrival of the R class in 1924 and scrapped in the late 1940s.

References

{{Garratt Builders B
A Brief History of the Garratt Locomotive in Australia ''[[Australian Railway History. Australian Railway Historical Society Bulletin]]'' issue 185 March 1953 page 25

Info: Wikipedia Source

This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page.

garratt-locomotives whyte-notation

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