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The reference for locomotives and railcars

Great Central class 9Q

London & North Eastern class B7

Great Britain 1921 38 produced
LNER 5474, ex No. 474, in August 1937 in Neasden transportsofdelight.smugmug.com

The class 9Q of the Great Central was a 4-6-0 mixed traffic locomotive designed by John Robinson. It was based on the class 9P “Lord Faringdon” express locomotive, but had smaller drivers with a diameter of five feet and eight inches (1,727 mm). Despite four cylinders, they had only two sets of valve gear which also controlled the outside cylinders via levers. Their primary role were express freights with passenger services only as second priority.

Starting in 1921, the GCR got 28 locomotives in four batches. After the grouping, the LNER designated them class B7 and built ten additional locomotives which had a lower boiler to comply with a smaller loading gauge. These were designated subclass B7/2, while the others were designated B7/1. Due to their high coal consumption, they got the nickname “Black Pigs”. All 38 came to British Railways, but were scrapped by 1950.

Technical data

General

Built
1921-1924
Manufacturers
Gorton, Vulcan Foundry, Beyer, Peacock & Co.
Wheel arrangement
4-6-0 (Ten-wheeler)
Gauge
1,435 mm (Standard gauge)

Dimensions and weights

Length
19.20 m
Wheelbase
8.61 m
Total wheelbase
16.09 m
Service mass
80.8 t
Adhesion mass
59.4 t
Total mass
129.9 t
Rigid wheelbase
4.39 m
Axle load
19.8 t
Water capacity
18,185 l
Fuel capacity
7.1 t (coal)

Boiler

Grate area
2.415 m²
Firebox surface
15.143 m²
Tube heating surface
174.751 m²
Evaporative heating surface
189.894 m²
Superheater surface
31.866 m²
Total heating surface
221.8 m²

Power plant

Driver diameter
1,727 mm
Boiler pressure
12.4 bar
Expansion type
simple expansion
Cylinders
four, 406 x 660 mm

Power

Power source
steam
Estimated power
1,007 kW (1,369 PS)
Starting effort
133.2 kN

Calculated values

Factor of adhesion
1 : 4.38
Optimal speed
47 km/h
Power-to-weight ratio
12.5 kW/t
Heating Surface Equivalent
329.3 m²
Cylinder volume/HSE
1 : 1,040.44
Adhesive weight/Total
1 : 1.36
Tractive force/Heating surface
1 : 12.55
Grate area/Heating surface
1 : 91.83
Firebox/Tube surface
1 : 11.54
Total/Superheater
1 : 5.96
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