Great Western Railway class 3200 “Earl” / “Dukedog”
After the GWR had taken over the Cambrian Railways, they needed modern locomotives for passenger services on these lines which only allowed a low axle load. Since there were none of these locomotives available, they decided to mount the superheated boiler of Duke class No. 3265 “Tre Pol and Pen” to the intact frames of Bulldog class No. 3365 “Charles Grey Mott” in 1929. This prototype retained the number and name of the Duke.
Because this prototype was successful, 29 further locomotives were built in the same way between 1936 and 1939. They got numbers from 3200 onwards and were officially called “Earl” class. Due to their origin being a mix of the Duke and Bulldog classes, they were also called “Dukedog”. The only one that has been preserved is No. 9017 “Earl of Berkeley”, which hasn't been operational since 2011.
Technical data
General
- Built
- 1929, 1936-1939
- Manufacturers
- Swindon
- Wheel arrangement
- 4-4-0 (American)
- Gauge
- 1,435 mm (Standard gauge)
Dimensions and weights
- Wheelbase
- 6.78 m
- Service mass
- 49.8 t
- Adhesion mass
- 30.9 t
- Total mass
- 90.4 t
- Rigid wheelbase
- 2.59 m
- Axle load
- 15.6 t
- Water capacity
- 15,910 l
- Fuel capacity
- 6.1 t (coal)
Boiler
- Grate area
- 1.598 m²
- Firebox surface
- 10.586 m²
- Tube heating surface
- 95.602 m²
- Evaporative heating surface
- 106.188 m²
- Superheater surface
- 6.968 m²
- Total heating surface
- 113.2 m²
Power plant
- Driver diameter
- 1,727 mm
- Boiler pressure
- 12.4 bar
- Expansion type
- simple expansion
- Cylinders
- two, 457 x 660 mm
Power
- Power source
- steam
- Estimated power
- 634 kW (862 PS)
- Starting effort
- 84.3 kN
Calculated values
- Factor of adhesion
- 1 : 3.59
- Optimal speed
- 47 km/h
- Power-to-weight ratio
- 12.7 kW/t
- Heating Surface Equivalent
- 173.1 m²
- Cylinder volume/HSE
- 1 : 1,253.02
- Adhesive weight/Total
- 1 : 1.61
- Tractive force/Heating surface
- 1 : 15.56
- Grate area/Heating surface
- 1 : 70.81
- Firebox/Tube surface
- 1 : 9.03
- Total/Superheater
- 1 : 15.24