Great Central class 9Q
London & North Eastern class B7
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