Articulated locomotive
Encyclopedia
Articulated locomotive usually means a steam locomotive
with one or more engine units which can move independent of the main frame. This is done to allow a longer locomotive to negotiate tighter curves. Articulated locomotives are generally used either on lines with extreme curvature—logging, industrial, or mountainous railways, for example—or to allow very large locomotives to run on railways with standard track curvature.
4-8-8-4
s and the Allegheny H-8 2-6-6-6
s were some of the largest steam locomotives ever built.
Many different schemes for articulation were developed over the years. Of these, the Mallet locomotive
and its simple-expansion derivative were the most popular, followed by the Garratt
type (mostly built in the United Kingdom
, popular throughout Europe
, Africa
and European colonies), and the various geared steam locomotive
types, the latter largely used in logging, mining and industry. Most other types saw only limited success.
, including:
s of generally two types:
Two-unit locomotives, e.g. Bo-Bo+Bo-Bo locomotives are not considered to be articulated but are permanently coupled together.
Electric and diesel bogie locomotives have many construction aspects in common with Meyer type steam locomotives but are not seen as articulated.
Steam locomotive
A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...
with one or more engine units which can move independent of the main frame. This is done to allow a longer locomotive to negotiate tighter curves. Articulated locomotives are generally used either on lines with extreme curvature—logging, industrial, or mountainous railways, for example—or to allow very large locomotives to run on railways with standard track curvature.
Usage
Articulated locomotives saw service in many nations, but were very popular on narrow gauge railways in Europe and saw their greatest size developed in the United States, where the Union Pacific Big BoyUnion Pacific Big Boy
Big Boy was the name of the Union Pacific Railroad's 4000-class 4-8-8-4 articulated steam locomotives, built between 1941 and 1944 by American Locomotive Company...
4-8-8-4
4-8-8-4
In the Whyte notation for the classification of steam locomotives by wheel arrangement, a 4-8-8-4 is a locomotive with a four-wheel leading truck, two sets of eight driving wheels, and a four-wheel trailing truck.Other equivalent classifications are:...
s and the Allegheny H-8 2-6-6-6
2-6-6-6
The 2-6-6-6 is an articulated locomotive type with 2 leading wheels, two sets of six driving wheels and six trailing wheels. Only two classes of the 2-6-6-6 type were built. One was the "Allegheny" class, built by the Lima Locomotive Works. The name comes from the locomotive's first service with...
s were some of the largest steam locomotives ever built.
Many different schemes for articulation were developed over the years. Of these, the Mallet locomotive
Mallet locomotive
The Mallet Locomotive is a type of articulated locomotive, invented by a Swiss engineer named Anatole Mallet ....
and its simple-expansion derivative were the most popular, followed by the Garratt
Garratt
A Garratt is a type of steam locomotive that is articulated in three parts. Its boiler is mounted on the centre frame, and two steam engines are mounted on separate frames, one on each end of the boiler. Articulation permits larger locomotives to negotiate curves and lighter rails that might...
type (mostly built in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
, popular throughout Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
and European colonies), and the various geared steam locomotive
Geared steam locomotive
A geared steam locomotive is a type of steam locomotive which uses reduction gearing in the drivetrain, as opposed to the common directly driven design....
types, the latter largely used in logging, mining and industry. Most other types saw only limited success.
Major types
These are the major types of articulated locomotive:- The FairlieFairlieA Fairlie is a type of articulated steam locomotive that has the driving wheels on bogies. The locomotive may be double-ended or single ended...
, with two powered trucks under a double boiler, or its Single Fairlie single-boiler derivative with one powered and one unpowered truck (known as a Mason BogieMason BogieThe Mason Bogie is a type of articulated steam locomotive suited for sharp curves and uneven track, once commonly used on narrow gauge lines in the United States...
in the United StatesUnited StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
). - The GarrattGarrattA Garratt is a type of steam locomotive that is articulated in three parts. Its boiler is mounted on the centre frame, and two steam engines are mounted on separate frames, one on each end of the boiler. Articulation permits larger locomotives to negotiate curves and lighter rails that might...
, with an engine unit at each end carrying coal and water supplies, and a boiler unit articulated between them. - The Mallet locomotiveMallet locomotiveThe Mallet Locomotive is a type of articulated locomotive, invented by a Swiss engineer named Anatole Mallet ....
, with one fixed engine under the rear of the locomotive and a radially swinging engine unit in front. - The Meyer locomotiveMeyer locomotiveA Meyer locomotive is a type of articulated locomotive. The design was never as popular as the Garratt or Mallet locomotives. It can be best regarded as 19th Century competition for the early compound Mallet and also the Fairlie articulated designs....
, with two powered engine trucks under the locomotive (generally with the cylinders inward). Also, the Kitson-Meyer variant with the trucks spread apart to allow a deeper firebox between them.
Geared types
There were various types of articulated geared steam locomotiveGeared steam locomotive
A geared steam locomotive is a type of steam locomotive which uses reduction gearing in the drivetrain, as opposed to the common directly driven design....
, including:
- Climax locomotiveClimax locomotiveA Climax locomotive is a type of geared steam locomotive in which the two steam cylinders were attached to a transmission located under the center of the boiler. This transmits power to driveshafts running to the front and rear trucks....
- Heisler locomotiveHeisler locomotiveThe Heisler locomotive was the last variant of the three major types of geared steam locomotive, Charles L. Heisler receiving a patent for the design in 1892 following the construction of a prototype in 1891. Somewhat similar to a Climax locomotive, Heisler's design featured two cylinders canted...
- Shay locomotiveShay locomotiveThe Shay locomotive was the most widely used geared steam locomotive. The locomotives were built to the patents of Ephraim Shay, who has been credited with the popularization of the concept of a geared steam locomotive...
Other types
- du Bousquet locomotiveDu Bousquet locomotiveThe du Bousquet locomotive was an unusual design of articulated steam locomotive invented by French locomotive designer Gaston du Bousquet.The design was a tank locomotive, carrying all its fuel and water on board the locomotive proper, and a compound locomotive...
- Engerth locomotiveEngerth locomotiveThe Engerth locomotive was a type of early articulated steam locomotive designed by Wilhelm Freiherr von Engerth for use on the Semmering Railway in Austria.- Designer :...
- Goelsdorf locomotiveGoelsdorf locomotiveThe Goelsdorf locomotive is a type of articulated locomotive for railway use. The articulation allows a larger locomotive to go around sharp curves.- History :...
- Golwé locomotiveGolwé locomotiveThe Golwé was a type of articulated steam locomotive manufactured in France for use in its West African colonies.The front engine unit swivelled under the boiler and smokestack, in a similar manner to a Meyer and looking somewhat like a Mallet; in contrast a Garratt had its front bogie in front of...
- Hagans locomotive, such as the Prussian T 13Prussian T 13The Prussian T 13 was a series of tank locomotives built in large numbers for the various German state railways, notably the Prussian state railways, and the Deutsche Reichsbahn during the early part of the 20th century.- T 13 :...
(Hagans variant) - Klein-LinderKlein-LinderKlein-Linder is a form of articulation for ordinary steam locomotives to make them more suitable for going around very sharp curves.- Examples :...
locomotive
Electric locomotives
There are several classes of articulated electric locomotiveElectric locomotive
An electric locomotive is a locomotive powered by electricity from overhead lines, a third rail or an on-board energy storage device...
s of generally two types:
- Three sections, where the middle part sits on the two outer parts (similar to the Garratt design)
- Milwaukee Road class EP-2Milwaukee Road class EP-2The Milwaukee Road's class EP-2 comprised five electric locomotives built by General Electric in 1919. They were often known as Bipolars, which referred to the bipolar electric motors they used. Among the most distinctive and powerful electric locomotives of their time, they epitomized the...
- :de:SBB Ce 6/8 II and :de:SBB Ce 6/8 III
- :de:DRB-Baureihe E 94
- Milwaukee Road class EP-2
- Two sections which share a central or JacobsJacobs bogieJacobs bogies are a type of rail vehicle bogie commonly found on articulated railcars and tramway vehicles....
bogie- FS Class E656FS Class E656The Class E656 is an Italian articulated rheostatic-type electric locomotive built from 1973 to 1989. An evolution of the E646/5, they are all-purpose locomotives, and have been used on every kind of train, ranging from freight to intercity passenger trasport.The E656 is nicknamed "Caimano" .-...
operating in ItalyItalyItaly , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and... - New Zealand EW classNZR EW classThe NZR EW class locomotive was a class of electric locomotive used in Wellington, New Zealand. The classification 'EW' was due to their being electric locomotives allocated to Wellington.- Introduction :...
, built by English ElectricEnglish ElectricEnglish Electric was a British industrial manufacturer. Founded in 1918, it initially specialised in industrial electric motors and transformers...
in 1952.
- FS Class E656
Two-unit locomotives, e.g. Bo-Bo+Bo-Bo locomotives are not considered to be articulated but are permanently coupled together.
Electric and diesel bogie locomotives have many construction aspects in common with Meyer type steam locomotives but are not seen as articulated.
See also
- Beyer Peacock
- Bissel bogieBissel bogieA Bissel truck is a very simple and commonly used way of designing a carrying axle on a steam locomotive to enable it to negotiate curves more easily. The design uses a single-axled bogie, usually known as a pony truck, whose pivot is towards the centre of the locomotive...
- Grovers bogie
- Jacobs bogieJacobs bogieJacobs bogies are a type of rail vehicle bogie commonly found on articulated railcars and tramway vehicles....
- Cleminson's patent radial axle