GNR O1 class LNER O1 (later O3) Class
No. 3491 at Immingham Locomotive Depot 1947
Type and origin Power type Steam Designer Nigel Gresley Builder Doncaster Works (5) North British Locomotive Co. (15) Build date 1913–1919 Total produced 20
Specifications Configuration: ​  • Whyte 2-8-0  • UIC 1′D h2 Gauge 4 ft 8+1⁄2 in (1,435 mm) Leading dia. 3 ft 2 in (965 mm) Coupled dia. 4 ft 8 in (1,422 mm) Length 60 ft 11.5 in (18.580 m) Loco weight 76.2–78.65 long tons (77.42–79.91 t) Fuel type Coal Firebox: ​  • Grate area 27 sq ft (2.5 m2) Boiler: ​  • Diameter 5 ft 6 in (1,680 mm) Boiler pressure 180 lbf/in2 (1.24 MPa) Heating surface: ​  • Firebox 162 sq ft (15.1 m2)  • Total surface 2,084 sq ft (193.6 m2) Superheater: ​  • Type 24  • Heating area 570 sq ft (53 m2) Cylinders Two, outside Cylinder size 21 in × 28 in (533 mm × 711 mm) Valve gear Walschaerts Valve type 10-inch (254 mm) piston valves
Performance figures Tractive effort 33,735 lbf (150.06 kN)
Career Operators Great Northern Railway (Great Britain) London and North Eastern Railway British Railways Power class 8F Nicknames Tangos Axle load class Route availability 6 Withdrawn 1947–1952 Disposition All scrapped

TheGreat Northern Railway (GNR)Class O1 was a class of two-cylinder2-8-0steam locomotive designed byNigel Gresley for heavy freight work and built by the GNR between 1913 and 1919.

Gresley designed the O1 2-8-0 for the heavy coal trains on the mainline from Grantham to London, ordering five examples 1913, which were completed at Doncaster in 1914. A further fifteen were ordered in January 1916, but due to theFirst World War delays were incurred and construction was transferred to theNorth British Locomotive Company, who delivered the first ten in April 1918, followed by a further five in October and November 1919.

The class was re-designated O3 by theLondon and North Eastern Railway in 1944 to release the O1 classification for use with theLNER Thompson Class O1 introduced during theSecond World War.

Seventeen examples survived into British Railways ownership in 1948, but all had been withdrawn by 1952 and scrapped afterWorld War 2 .

• Boddy, M. G.; Brown, W. A.; Neve, E.;Yeadon, W. B. (November 1983). Fry, E. V. (ed.).Locomotives of the L.N.E.R., Part 6B: Tender Engines—Classes O1 to P2. Kenilworth:RCTS.ISBN 0-901115-54-1.

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• Great Northern Railway (Great Britain) locomotives
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• Scrapped locomotives
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• 2-8-0 locomotives

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