4-4-2+2-4-4

4-4-2+2-4-4 (Double Atlantic)

Equivalent classifications UIC class 2B1+1B2 French class 221+122 Turkish class 25+25 Swiss class 2/5+2/5, 4/10 from the 1920s Russian class 2-2-1+1-2-2

First known tank engine version First use 1912 Country Australia Locomotive TGR M class Railway Tasmanian Government Railways Designer Beyer, Peacock & Company Builder Beyer, Peacock & Company

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.

4-4-2+2-4-4 Garratt production list – All manufacturers

Gauge	Railway	Class	Works no.	Units	Year	Builder
3 ft 6 in	Tasmanian Government Railways	M	5523–5524	2	1912	Beyer, Peacock & Company
4 ft 8+1⁄2 in	Entre Ríos Railway, Argentina		6360–6364	5	1927	Beyer, Peacock & Company
4 ft 8+1⁄2 in	Argentine North Eastern Railway		6645–6647	3	1930	Beyer, Peacock & Company

Usage

Argentina

Eight locomotives were built for Argentina to run on 4 ft 8+1⁄2 in (1,435 mm) standard gauge.

• 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 3 ft 6 in (1,067 mm) 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 They were difficult to maintain and, despite their haulage abilities and speed, both were withdrawn from service some time after the arrival of the R class in 1924 and scrapped in the late 1940s.

External links

Media related to 4-4-2+2-4-4 locomotives at Wikimedia Commons