London & North Western Dreadnought class
The Dreadnought class was the larger successor of the 2-2-2-0 Experiment class. Both were three-cylinder Webb compounds with divided drive. As such, both classes had two small outside high pressure cylinders, driving the rear set of drivers and a large inside low pressure cylinder, driving the first set of drivers. Crewe works delivered 40 locomotives between 1884 and 1888. When the PRR ordered a single demonstrator in the following year, this had to be constructed by Beyer, Peacock & Co. as the Crewe works were only allowed to build locomotives for the LNWR. It was numbered 1320 and was virtually identical to the LNWR design.
The new class had a larger boiler pressed to 175 instead of 150 psi and larger cylinders. The drivers of the Dreadnought class only measured six and a quarter feet, instead of the six and a half feet of the Experiment class. This further increased their tractive effort, while still allowing high speeds. The new class originally had Joy valve gear for both the outside and inside cylinders, but the inside one was later changed to the slip-eccentric type also found on the Experiment class. The whole class was withdrawn between 1903 and 1905 under George Whale, as the design was too complicated.
Technical data
General
- Built
- 1884-1888
- Manufacturers
- Crewe
- Wheel arrangement
- 2-2-2-0 (Webb Compound)
- Gauge
- 1,435 mm (Standard gauge)
Dimensions and weights
- Wheelbase
- 5.51 m
- Rigid wheelbase
- 2.95 m
- Service weight
- 43.2 t
- Adhesive weight
- 29.5 t
- Axle load
- 15.2 t
- Total weight
- 68.6 t
- Water capacity
- 8,184 l
- Fuel capacity
- 5.1 t (coal)
Boiler
- Grate area
- 1.905 m²
- Firebox surface
- 14.781 m²
- Tube heating surface
- 115.376 m²
- Evaporative heating surface
- 130.157 m²
- Total heating surface
- 130.2 m²
Power plant
- Driver diameter
- 1,905 mm
- Boiler pressure
- 12.1 bar
- Expansion type
- compound
- Cylinders
- three, HP: 356 x 610 mm and LP: 762 x 610 mm
Power
- Power source
- steam
- Estimated power
- 597 kW (812 PS)
- Starting effort
- 51.1 kN
- Starting effort simple
- 61.3 kN
Calculated values
- Factor of adhesion
- 1 : 4.71
- Optimal speed
- 71 km/h
- Power-to-weight ratio
- 13.8 kW/t
- Heating Surface Equivalent
- 204.1 m²
- Cylinder volume/HSE
- 1 : 1,466.78
- Adhesive weight/Total
- 1 : 1.47
- Tractive force/Heating surface
- 1 : 9.84
- Grate area/Heating surface
- 1 : 68.32
- Firebox/Tube surface
- 1 : 7.81