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The reference for locomotives and railcars

Great Western Railway class 3200 “Earl” / “Dukedog”

Great Britain 1929 30 produced
No. 9017 “Earl of Berkeley” in September 2008 Roger Carvell / The 'Earl of Berkeley' leaves Highley for Kidderminster, 2008 CC BY 3.0

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
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