Cambrian Railways class 61
William Aston, who had been chief engineer of the Cambrian since 1882, had already revised the six Beaconsfield class locomotives to cope with the increased train weights and tighter schedules. This concerned the express trains that transported holidaymakers to the tourist areas of Wales. From 1893, class 61 locomotives were ordered to meet the increased requirements in this task, which essentially were an enlargement of the Beaconsfield class.
Compared to their predecessors, the locomotives received larger cylinders, larger drivers and a new boiler with 20 psi higher pressure and a larger firebox with larger grate. In the years 1893 to 1895, 16 were made by Sharp, Stewart & Co., which received the numbers 61 to 72 and 81 to 84. Five more followed in 1897 from Robert Stephenson & Co., numbered 32, 47, 11, 85 and 86. Number 19 was special as it was only built in 1901 in the Cambrian Railway's own workshops in Oswestry.
Technical data
General
- Built
- 1893-1895, 1897, 1901
- Manufacturers
- Sharp, Stewart & Co., Robert Stephenson & Co., Owestry
- Wheel arrangement
- 4-4-0 (American)
- Gauge
- 1,435 mm (Standard gauge)
Dimensions and weights
- Wheelbase
- 6.19 m
- Service mass
- 40.9 t
- Adhesion mass
- 27.7 t
- Total mass
- 71.4 t
- Rigid wheelbase
- 2.52 m
- Axle load
- 15.2 t
- Water capacity
- 11,364 l
- Fuel capacity
- 4.6 t (coal)
Boiler
- Grate area
- 1.579 m²
- Firebox surface
- 9.244 m²
- Tube heating surface
- 98.199 m²
- Evaporative heating surface
- 107.442 m²
- Total heating surface
- 107.4 m²
Power plant
- Driver diameter
- 1,829 mm
- Boiler pressure
- 11 bar
- Expansion type
- simple expansion
- Cylinders
- two, 457 x 610 mm
Power
- Power source
- steam
- Estimated power
- 429 kW (583 PS)
- Starting effort
- 65.3 kN
Calculated values
- Factor of adhesion
- 1 : 4.16
- Optimal speed
- 40 km/h
- Power-to-weight ratio
- 10.5 kW/t
- Heating Surface Equivalent
- 153.7 m²
- Cylinder volume/HSE
- 1 : 1,302.59
- Adhesive weight/Total
- 1 : 1.48
- Tractive force/Heating surface
- 1 : 12.70
- Grate area/Heating surface
- 1 : 68.04
- Firebox/Tube surface
- 1 : 10.62