4-14-4
Encyclopedia
Whyte notation
The Whyte notation for classifying steam locomotives by wheel arrangement was devised by Frederick Methvan Whyte and came into use in the early twentieth century encouraged by an editorial in American Engineer and Railroad Journal...
for the classification of steam locomotive
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...
s by wheel arrangement
Wheel arrangement
In rail transport, a wheel arrangement is a system of classifying the way in which wheels are distributed beneath a locomotive.. Several notations exist to describe the wheel assemblies of a locomotive by type, position, and connections, with the adopted notations varying by country...
, is a locomotive with four leading wheel
Leading wheel
The leading wheel or leading axle 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 in a truck...
s, fourteen coupled driving wheel
Driving wheel
On a steam locomotive, a driving wheel is a powered wheel which is driven by the locomotive's pistons...
s (seven axles) in a rigid frame, and four trailing wheel
Trailing wheel
On a steam locomotive, a trailing wheel or trailing axle is generally an unpowered wheel or axle located behind the driving wheels. The axle of the trailing wheels was usually located on a trailing truck...
s.
Other equivalent classifications are:
UIC classification
UIC classification
The UIC classification of locomotive axle arrangements describes the wheel arrangement of locomotives, multiple units and trams. It is set out in the International Union of Railways "Leaflet 650 - Standard designation of axle arrangement on locomotives and multiple-unit sets". It is used in much...
: 2G2 (also known as German classification and Italian classification)
French classification: 272
Turkish classification
Turkish classification
In the Turkish classification system for railway locomotives, the number of powered axles are followed by the total number of axles. It is identical to the Swiss system except that the latter places a slash between the two numbers.Thus0-6-0 becomes 33...
: 711
Swiss classification: 7/11
Russian classification: 2-7-2
A single example of this type, called the AA20-1, was built by the Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
. The designation stands for Andrey Andreev (who sponsored its construction), 20 ton axle load. While some builders had produced twelve-coupled (six driving axles) designs, no one had ever built a fourteen-coupled engine. The AA20-1 holds two records: the largest number of coupled axles on a locomotive, and being the longest rigid frame locomotive in Europe. It was the largest rigid frame locomotive in the world until 1939, when the PRR S1
PRR S1
The PRR S1 class steam locomotive was an experimental locomotive that was the largest rigid frame passenger locomotive ever built. The streamlined Art Deco styled shell of the locomotive was designed by Raymond Loewy....
was unveiled.
The large number of driving axles were meant to spread out the locomotive's weight, reducing the axle load
Axle load
The axle load of a wheeled vehicle is the total weight felt by the roadway for all wheels connected to a given axle. Viewed another way, it is the fraction of total vehicle weight resting on a given axle...
and the resulting stress on the track. A group of Soviet locomotive engineers had visited the United States, and presumably they had seen the 4-12-2
4-12-2
Under the Whyte notation for the classification of steam locomotives, 4-12-2 represents the wheel arrangement of four leading wheels, twelve coupled driving wheels, and two trailing wheels.Other equivalent classifications are:...
locomotives being used by the Union Pacific. The 4-14-4 could be viewed as an expansion of that type. Unlike the successful Union Pacific locomotives, however, the AA20-1 was a complete disaster.
The AA20-1 was originally intended to be a 2-14-4 (1'G2'). Construction was undertaken in Essen
Essen
- Origin of the name :In German-speaking countries, the name of the city Essen often causes confusion as to its origins, because it is commonly known as the German infinitive of the verb for the act of eating, and/or the German noun for food. Although scholars still dispute the interpretation of...
, Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
by Krupp, following a Soviet design. Later, the unfinished locomotive was moved to Lugansk, where a two-axle leading truck was fitted. The trailing truck supported a huge firebox. The AA20-1 was intended to run on low-quality coal, so a lot of space was needed to burn it in order to provide enough heat to the boiler.
The seven driving axles made for a very long rigid wheelbase, and provisions were made to negotiate curves. The center three driving axles were blind, and the first and seventh driving axles were fitted with lateral motion device
Lateral motion device
Lateral motion devices permit the axles in some railroad locomotives to move sideways relative to the frame.-Purpose:The coupled driving wheels on steam locomotives were held in a straight line by the locomotive's frame...
s. These measures were not enough to make the AA20-1 work properly, however. It was prone to frequent derailments, and despite its large number of wheels, it was still too heavy for the track. As a result of its long wheelbase, the AA20-1 also spread the track and wrecked the points of the switches
Railroad switch
A railroad switch, turnout or [set of] points is a mechanical installation enabling railway trains to be guided from one track to another at a railway junction....
it passed over. It was too big to fit on the turntables
Turntable (railroad)
A railway turntable is a device for turning railroad rolling stock. When steam locomotives were still in wide use, many railroads needed a way to turn the locomotives around for return trips as their controls were often not configured for extended periods of running in reverse and in many...
, too powerful for the couplers
Coupling (railway)
A coupling is a mechanism for connecting rolling stock in a train. The design of the coupler is standard, and is almost as important as the railway gauge, since flexibility and convenience are maximised if all rolling stock can be coupled together.The equipment that connects the couplings to the...
in use at the time and unable to run at full power for very long due to its undersized boiler
Boiler
A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications.-Materials:...
.
The AA20-1 made a publicity trip to Moscow in 1935. It was then put into storage and later scrapped, though this was not stated publicly.