The reference for locomotives and railcars


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US Railroad Administration Light Mountain
Missouri Pacific class MT-69, Nashville, Chattanooga & St. Louis class J1-54, New Haven class R-1 and Southern Railway (USA) class Ts-1
United States | 1918 | 47 produced
New Haven No. 3320 in June 1940 in Boston
New Haven No. 3320 in June 1940 in Boston

The USRA Light Mountain was planned as a light standard freight locomotive and had a boiler slightly larger than that of the Heavy Pacific or the Heavy Mikado. It was almost 20,000 pounds lighter than the Heavy Mountain, had cylinders that were an inch smaller in diameter, and the same driver diameter. A total of 47 were built, with the Southern Railway getting the most at 25. The rest went to the Missouri Pacific, the Nashville, Chattanooga & St. Louis, and the New Haven. By 1930, 90 more copies had been built.

ManufacturerALCO, Baldwin
Axle config4-8-2 (Mountain) 
Gauge4 ft 8 1/2 in (Standard gauge)
Dimensions and Weights
Wheelbase40 ft
Fixed wheelbase18 ft 3 in
Total wheelbase75 ft 8 1/2 in
Service weight327,000 lbs
Adhesive weight224,500 lbs
Total weight520,700 lbs
Axle load56,500 lbs
Water capacity10,000 us gal
Fuel capacity32,000 lbs (coal)
Power sourcesteam
Estimated power3,250 hp (2,424 kW)
Optimal speed38 mph
Starting effort53,883 lbf
Power Plant
Driver diameter69 in
Boiler pressure200 psi
Expansion typesimple
Cylinderstwo, 27 x 30 in
Grate area70.3 sq ft
Firebox area348 sq ft
Tube heating area3,773 sq ft
Evaporative heating area4,121 sq ft
Superheater area966 sq ft
Total heating area5,087 sq ft
Calculated Values
steam locomotive
last changed: 07/2023

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