The GER Class A55 or ''Decapod'' was an experimental

steam locomotive A steam locomotive is a locomotive that provides the force to move itself and other vehicles by means of the expansion of steam. It is fuelled by burning combustible material (usually coal, Fuel oil, oil or, rarely, Wood fuel, wood) to heat ...

with an

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 ...

Great Eastern Railway The Great Eastern Railway (GER) was a pre-grouping British railway company, whose main line linked London Liverpool Street to Norwich and which had other lines through East Anglia. The company was grouped into the London and North Eastern R ...

. It was the first ten-coupled steam locomotive in

Great Britain Great Britain is an island in the North Atlantic Ocean off the north-west coast of continental Europe, consisting of the countries England, Scotland, and Wales. With an area of , it is the largest of the British Isles, the List of European ...

Background

The locomotive was built for purely political purposes in order to block the passage through Parliament of a new rival scheme for an electric railway. The Decapod was built in 1902 to a design by the GER Chief Draughtsman, Fred Russell under the supervision of the Chief Superintendent, James Holden. The aim was to demonstrate the ability of a steam locomotive to accelerate passenger trains at a rate comparable to electric traction and the electric trams with which the GER was also in competition over short distances. The locomotive was far larger than any locomotive previously built in Britain for home service. It had 10

driving wheel On a steam locomotive, a driving wheel is a powered wheel which is driven by the locomotive's pistons (or turbine, in the case of a steam turbine locomotive). On a conventional, non-articulated locomotive, the driving wheels are all coupled t ...

s for maximum grip and prevention of wheelspin, each of which was four-foot-six-inches in diameter which gave high

tractive effort In railway engineering, the term tractive effort describes the pulling or pushing capability of a locomotive. The published tractive force value for any vehicle may be theoretical—that is, calculated from known or implied mechanical proper ...

. Three cylinders were used because there was insufficient room for two cylinders large enough to develop the required tractive effort without going up to a higher boiler pressure. Even so, it still had to have a pressure of 200

psi Psi, PSI or Ψ may refer to: Alphabetic letters * Psi (Greek) (Ψ or ψ), the twenty-third letter of the Greek alphabet * Psi (Cyrillic), letter of the early Cyrillic alphabet, adopted from Greek Arts and entertainment * "Psi" as an abbreviat ...

(1,380

kPa The pascal (symbol: Pa) is the unit of pressure in the International System of Units (SI). It is also used to quantify internal pressure, stress, Young's modulus, and ultimate tensile strength. The unit, named after Blaise Pascal, is an SI ...

) to achieve the required result.

Technical details

The engine was fitted with a large Wootten firebox. There were three separate grates and ash pans, one on each side outside the frames and a third between, giving an aggregate area of . The trailing drivers were given a side play of , the coupling rods being fitted with ball and socket joints. As the cranks of the three cylinders were set at 120 degrees in relation to each other, perfect balancing of the reciprocating parts was secured. In order to minimise the drivers slipping, compressed air sanders were fitted.

Performance

The specification required that the locomotive should accelerate a train from a stand to in 30 seconds, an acceleration of 1.46 feet per second per second. According to Ahrons, "Holden's engine actually accelerated a new train of eighteen coaches, weighing 335 tons, at a rate of 1.4ft. per second per second in very windy weather." Axle load at 16.75 tons (17 tonnes) was not excessive, but weight per foot run of wheelbase was very high and using a class of these engines would have necessitated considerable strengthening of bridges. Thus whilst it achieved its design aims, nothing resulted from the experiment.

Rebuilt

As the locomotive was therefore surplus to requirements, it was rebuilt in 1906, and converted into an freight tender engine. The rebuild included a new boiler with a Belpaire firebox and a standard GE high-sided goods locomotive tender. Number 20 was then assigned to March district for hauling coal trains, but proved no more capable than the Class G58 locomotives. The design was therefore not repeated, and the locomotive remained the only eight-coupled engine of the GER. It was scrapped in 1913 as nonstandard after a short working life.

0-10-0 developments

The

Midland Railway The Midland Railway (MR) was a railway company in the United Kingdom from 1844 in rail transport, 1844. The Midland was one of the largest railway companies in Britain in the early 20th century, and the largest employer in Derby, where it had ...

produced the second 0-10-0 locomotive in 1919 with its MR 0-10-0 Lickey Banker. The third ten-coupled engine however would not appear until 1943 in the guise of a class of

2-10-0 Under the Whyte notation for the classification of steam locomotives, 2-10-0 represents the wheel arrangement of two leading wheels on one axle, ten powered and coupled driving wheels on five axles, and no trailing wheels. This arrangement was of ...

s built by the War Department, the Austerity 2-10-0. These were followed in 1954 by the last class of British ten-coupled engines, the

BR Standard Class 9F The British Railways Standard Class 9F is a class of steam locomotive designed for British Railways by Robert Riddles. The Class 9F was the last in a series of standardised locomotive classes designed for British Railways during the 1950s, a ...

In fiction

In the 2017 film, '' Thomas & Friends: Journey Beyond Sodor'', the character

Hurricane A tropical cyclone is a rapidly rotating storm system with a low-pressure area, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depending on its ...

is based on this engine before it was rebuilt.

References

External links

Mixed Traffic Locomotives
''Mike's Railway History'' {{Great Eastern Railway locomotives A55 0-10-0T locomotives 0-8-0 locomotives Railway locomotives introduced in 1902 Standard-gauge steam locomotives of Great Britain Individual locomotives of Great Britain Experimental locomotives Scrapped locomotives E n3t locomotives D n2 locomotives Freight locomotives Unique locomotives