Soo Line class N-20
United States 1926 21 produced
These updated USRA Light Mountains were built to accelerate freight traffic on a single track main line. The first ten were built by ALCO-Brooks in 1926, eight more in 1928 by ALCO in Schenectady, and the last three in 1930 by the Soo Line's Shoreham Works in Minneapolis. There were minimal differences in weight between the individual batches. The tenders initially had a capacity of 10,000 gallons of water and 16 short tons of coal. These were later enlarged and some locomotives also received completely new, larger tenders.
Technical data
General
- Built
- 1926-1930
- Manufacturers
- ALCO, Shoreham
- Wheel arrangement
- 4-8-2 (Mountain)
- Gauge
- 1,435 mm (Standard gauge)
Dimensions and weights
- Length
- 26.94 m
- Wheelbase
- 12.45 m
- Service mass
- 155.1 t
- Adhesion mass
- 105 t
- Total mass
- 233.1 t
- Rigid wheelbase
- 5.56 m
- Axle load
- 26.3 t
- Water capacity
- 45,425 l
- Fuel capacity
- 15.9 t (coal)
Boiler
- Grate area
- 6.531 m²
- Firebox surface
- 31.68 m²
- Tube heating surface
- 320.33 m²
- Evaporative heating surface
- 352.01 m²
- Superheater surface
- 102.472 m²
- Total heating surface
- 454.5 m²
Power plant
- Driver diameter
- 1,753 mm
- Boiler pressure
- 13.8 bar
- Expansion type
- simple expansion
- Cylinders
- two, 686 x 762 mm
Power
- Power source
- steam
- Estimated power
- 2,424 kW (3,296 PS)
- Starting effort
- 239.7 kN
- Starting effort booster
- 52.489 kN
Calculated values
- Factor of adhesion
- 1 : 4.30
- Optimal speed
- 61 km/h
- Power-to-weight ratio
- 15.6 kW/t
- Heating Surface Equivalent
- 715.4 m²
- Cylinder volume/HSE
- 1 : 786.95
- Adhesive weight/Total
- 1 : 1.48
- Tractive force/Heating surface
- 1 : 11.01
- Grate area/Heating surface
- 1 : 69.59
- Firebox/Tube surface
- 1 : 10.11
- Total/Superheater
- 1 : 3.44
