Under the
Whyte notation
Whyte notation is a classification method for steam locomotives, and some internal combustion locomotives and electric locomotives, by wheel arrangement. It was devised by Frederick Methvan Whyte, and came into use in the early twentieth cen ...
for the classification of
steam locomotives by
wheel arrangement
In rail transport, a wheel arrangement or wheel configuration is a system of classifying the way in which wheels are distributed under a locomotive. Several notations exist to describe the wheel assemblies of a locomotive by type, position, and c ...
, is an
articulated locomotive
An articulated locomotive is a steam locomotive (rarely, an electric locomotive) with one or more engine units that can move independent of the main frame. Articulation allows the operation of locomotives that would otherwise be too large to neg ...
, usually of the
Garratt type. The wheel arrangement is effectively two locomotives operating back to back, with the
boiler
A boiler is a closed vessel in which fluid (generally water) is heated. The fluid does not necessarily boil. The heated or vaporized fluid exits the boiler for use in various processes or heating applications, including water heating, centr ...
and
cab suspended between the two power units. Each power unit has two
leading wheel
The leading wheel or leading axle or pilot wheel of a steam locomotive is an unpowered wheel or axle located in front of the driving wheels. The axle or axles of the leading wheels are normally located on a leading truck. Leading wheels are used ...
s on one axle, four powered and coupled
driving wheels on two axles and no
trailing wheel
On a steam locomotive, a trailing wheel or trailing axle is generally an unpowered wheel or axle ( wheelset) located behind the driving wheels. The axle of the trailing wheels is usually located in a trailing truck. On some large locomotives, ...
s. A similar wheel arrangement exists for
Mallet locomotives, but is referred to as
2-4-4-2
In Whyte notation, 2-4-4-2 refers to a railroad steam locomotive that has two leading wheels followed by four coupled driving wheels, a second set of four coupled driving wheels, and two trailing wheels.
Equivalent classifications
Other equival ...
since only the front engine unit can pivot.
Overview
This was the second rarest Garratt wheel arrangement. Only five locomotives were constructed to this arrangement, four of which were built by
Beyer, Peacock and Company
Beyer, Peacock and Company was an English railway locomotive manufacturer with a factory in Openshaw, Manchester. Founded by Charles Beyer, Richard Peacock and Henry Robertson, it traded from 1854 until 1966. The company exported locomotives, ...
(BP).
The four BP locomotives comprised three for the
São Paulo Railway of
Brazil
Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
in 1915, and one for the gauge
Ceylon Government Railway
The Sri Lanka Railway Department (more commonly known as Sri Lanka Railways (SLR)) ( Sinhala: ශ්රී ලංකා දුම්රිය සේවය ''Śrī Laṃkā Dumriya Sēvaya''; Tamil: இலங்கை புகையிரத ...
(CGR) in 1929, the
CGR's class H1.
One more was built in 1919 by the
São Paulo Railway, for its own use on .
Usage
Brazil
Ceylon
The single class H1 Garratt entered service on the Ceylon Government Railways in 1931. It was used in mixed traffic working on the
Uda Pussellawa railway. Until the 1960s, the locomotive was occasionally operated on the
Kelani Valley Line
The Kelani Valley railway line in Sri Lanka, covering the breadth of Colombo District. The line is owned, maintained, and operated by Sri Lanka Railways.
Route definition and overview
The Kelani Valley line runs southeast from Colombo Maradana ...
. It was withdrawn from service in 1972 and was scrapped in 1981.
References
4,2-4-0
44,2-4-0+0-4-2
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