The reference for locomotives and railcars


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Soo Line class N-20
United States | 1926 | 21 produced
No. 4000 in May 1954 at North Fond du Lac, Wisconsin
No. 4000 in May 1954 at North Fond du Lac, Wisconsin
Harold K. Vollrath

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 series. 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.

ManufacturerALCO, Shoreham
Axle config4-8-2 (Mountain) 
Gauge4 ft 8 1/2 in (Standard gauge)
Dimensions and Weights
Length88 ft 4 1/2 in
Wheelbase40 ft 10 in
Fixed wheelbase18 ft 3 in
Service weight342,000 lbs
Adhesive weight231,500 lbs
Total weight513,800 lbs
Axle load57,900 lbs
Water capacity12,000 us gal
Fuel capacity35,000 lbs (coal)
Power sourcesteam
Estimated power3,250 hp (2,424 kW)
Optimal speed38 mph
Starting effort53,883 lbf
Booster11,800 lbf
Power Plant
Driver diameter69 in
Boiler pressure200 psi
Expansion typesimple
Cylinderstwo, 27 x 30 in
Grate area70.3 sq ft
Firebox area341 sq ft
Tube heating area3,448 sq ft
Evaporative heating area3,789 sq ft
Superheater area1,103 sq ft
Total heating area4,892 sq ft
Calculated Values
steam locomotive
last changed: 03/2023

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