GER Class A55

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GER Class A55
GER Decapod.jpg
Type and origin
Power type Steam
Designer James Holden
Builder Stratford Works
Order number A55
Build date 1902
Total produced 1
 • Whyte 0-10-0WT
 • UIC E n3t
Gauge 4 ft 8 12 in (1,435 mm)
Driver dia. 4 ft 6 in (1.372 m)
Loco weight 80 long tons 0 cwt (179,200 lb or 81.3 t)
Fuel capacity 2 long tons 0 cwt (4,500 lb or 2 t)
Water cap 1,300 imp gal (5,900 l; 1,600 US gal)
 • Firegrate area
42 sq ft (3.9 m2)
Boiler length: 15 ft 6 in (4.724 m)
inside dia: 5 ft 3 in (1.600 m)
Heating surface 2,873.3 sq ft (266.94 m2)
 • Tubes 395 x 1.75 in (44.5 mm) dia
 • Firebox 131.7 sq ft (12.24 m2)
Cylinders Three
Cylinder size 18.5 in × 24 in (470 mm × 610 mm)
Performance figures
Tractive effort 38,788 lbf (172.54 kN)
Operators Great Eastern Railway
Class A55
Number in class 1
Numbers 20
Nicknames Decapod
Disposition Rebuilt in 1906 as 0-8-0 and later scrapped

The GER Class A55 or Decapod was an experimental steam locomotive with an 0-10-0T wheel arrangement designed by James Holden for the Great Eastern Railway. It was the first ten-coupled steam locomotive in Great Britain.


James Holden stands in front of his locomotive.

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[1] 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 four-foot-six-inch driving wheels, which gave high tractive effort. 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 (1,378 kPa) [2] to achieve the required result.

Technical details[edit]

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 42 sq ft (3.90 m2). The trailing drivers were given a side play of 0.5 in (12.7 mm), 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[citation needed].


The specification required that the locomotive should accelerate 315 ton (305 tonne) train from a stand to 30-mile-per-hour (48 km/h) in 30 seconds. According to Ahrons, "Holden's engine actually accelerated a new train of 18 carriages weighing 335 tons (340 tonnes) at a rate of 1.4 feet/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 aims, nothing resulted from the experiment.


GER Class A55R
GER Decapod, rebuilt as 0-8-0 (Boys' Book of Locomotives, 1907).jpg
As rebuilt to an 0-8-0
Type and origin
Power type Steam
Rebuilder Stratford Works
Rebuild date 1906
Number rebuilt 1
 • Whyte 0-8-0
 • UIC D n2
Gauge 4 ft 8 12 in (1,435 mm)
Driver dia. 4 ft 6 in (1.372 m)
Wheelbase 23 ft 3 in (7.09 m)
Length 56 ft 11 in (17.35 m) over buffers
Loco weight 54 long tons 6.75 cwt (121,700 lb or 55.2 t)
Tender weight 38 long tons 5 cwt (85,700 lb or 38.9 t)
Total weight 92 long tons 11.75 cwt (207,400 lb or 94.1 t)
Boiler Inside length: 12 ft 11 34 in (3.956 m)
Diameter: 4 ft 9 in (1.448 m)
Boiler pressure 180 psi (1.24 MPa)
Heating surface 1,869 sq ft (173.6 m2)
 • Tubes 1,738 sq ft (161.5 m2)
 • Flues 22.9 sq ft (2.1 m2)
 • Firebox 131 sq ft (12.2 m2)
Cylinders Two, outside
Cylinder size 18.5 in × 24 in (470 mm × 610 mm)
Operators Great Eastern Railway
Numbers 20
Scrapped 1913

As the locomotive was therefore surplus to requirements, it was rebuilt in 1906, and converted into an 0-8-0 freight tender engine. The rebuild included a new boiler with a Belpaire firebox and a standard GE high-sided goods locomotive tender.[3]

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[4] as nonstandard after a short working life.

0-10-0 developments[edit]

The Midland Railway 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 2-10-0s 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.


  1. ^ "James Holden, S.D. Holden, A.J. Hill & F.V. Russell". Retrieved 4 November 2007. 
  2. ^ Ahrons E.L., The British Steam Railway Locomotive, 1825-1925: Locomotive Publishing Co. 1925 (republished Ian Allan, 1963), pp. 337–8
  3. ^ Aldrich 1969, p. 41
  4. ^ Boddy, M. G.; Brown, W. A.; Hennigan, W.; Hoole, Ken; Neve, E.; Yeadon, W. B. (September 1984). Fry, E. V., ed. Locomotives of the L.N.E.R., Part 6C: Tender Engines—Classes Q1 to Y10. Kenilworth: RCTS. p. 3. ISBN 0-901115-55-X. 
  • Aldrich, C. Langley (1969). The Locomotives of the Great Eastern Railway 1862–1962 (7th ed.). Wickford, Essex: C. Langley Aldrich. OCLC 30278831. 

External links[edit]