Lancashire & Yorkshire Hughes 4-6-4T “Dreadnought Tanks”
London, Midland & Scottish class 5P
Based on the class 8 “Dreadnought”, George Hughes developed a tank locomotive that was also intended for express service. Thanks to the trailing bogie, it now had a 4-6-4T wheel arrangement. The boiler with Belpaire firebox basically resembled the original, but was somewhat lighter. There were no changes to the 75-inch (1,905 mm) diameter driving wheels and the four 16.5-inch (419 mm) diameter cylinders.
Although they had been developed for the Lancashire & Yorkshire Railway, the ten locomotives were directly delivered to the LMS in 1924 and were designated class 5P. They were also known as “Dreadnought Tanks”. However, due to their heavy weight, their possible uses were limited, so that they could only be used between Manchester and Blackpool. A further order for 20 was therefore converted into class 8. The tank locomotives were withdrawn from service between 1938 and 1941.
Technical data
General
- Built
- 1924
- Manufacturers
- Horwich
- Wheel arrangement
- 4-6-4T (Hudson)
- Gauge
- 1,435 mm (Standard gauge)
Dimensions and weights
- Length
- 15.20 m
- Wheelbase
- 12.29 m
- Service mass
- 101.6 t
- Adhesion mass
- 56.9 t
- Rigid wheelbase
- 4.14 m
- Axle load
- 19 t
- Water capacity
- 9,093 l
- Fuel capacity
- 4.1 t (coal)
Boiler
- Grate area
- 2.75 m²
- Firebox surface
- 16.723 m²
- Tube heating surface
- 168.805 m²
- Evaporative heating surface
- 185.528 m²
- Superheater surface
- 31.866 m²
- Total heating surface
- 217.4 m²
Power plant
- Driver diameter
- 1,905 mm
- Boiler pressure
- 12.4 bar
- Expansion type
- simple expansion
- Cylinders
- four, 419 x 660 mm
Power
- Power source
- steam
- Estimated power
- 1,081 kW (1,470 PS)
- Starting effort
- 128.5 kN
Calculated values
- Factor of adhesion
- 1 : 4.35
- Optimal speed
- 51 km/h
- Power-to-weight ratio
- 10.6 kW/t
- Heating Surface Equivalent
- 332.9 m²
- Cylinder volume/HSE
- 1 : 1,094.74
- Adhesive weight/Total
- 1 : 1.78
- Tractive force/Heating surface
- 1 : 12.34
- Grate area/Heating surface
- 1 : 79.05
- Firebox/Tube surface
- 1 : 10.09
- Total/Superheater
- 1 : 5.82