The reference for locomotives and railcars


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Southern Pacific classes MT-1, MT-3, MT-4 and MT-5
United States | 1923 | 77 produced
MT-3 No. 4332 with Skyline Casing in April 1952 in San Francisco
MT-3 No. 4332 with Skyline Casing in April 1952 in San Francisco
Henry Bender / collection Taylor Rush

The Mountains of the Southern Pacific were intended for long-range passenger trains, sometimes covering more than 800 miles without changing locomotives. The first 28 MT-1s were built by ALCO in Schenectady in 1923 and 1924. The additional batches built by the SP in Sacramento from 1925 to 1930 and totalling 49 were designated MT-3 through MT-5. The MT-2 class was used for six similar locomotives built for the El Paso & Southwestern.

The use of high-tensile steel made lightweight construction possible, which allowed for a larger boiler without exceeding the weight limits. The moving masses in particular were made lighter to improve running at high speeds. They also received a booster on the trailing axle and a Worthington feed water heater. In addition, some, like the one pictured, were retrofitted with a skyline casing on top of the boiler.

Most of the time they were used in front of long-range passenger trains, but also in front of freight trains. In later years they were used in fast suburban traffic. All were scrapped between 1954 and 1959.

ManufacturerALCO, Sacramento
Axle config4-8-2 (Mountain) 
Gauge4 ft 8 1/2 in (Standard gauge)
Dimensions and Weights
Wheelbase42 ft 3 in
Fixed wheelbase20 ft
Total wheelbase83 ft 6 in
Service weight368,000 lbs
Adhesive weight246,000 lbs
Total weight610,400 lbs
Axle load61,800 lbs
Water capacity12,000 us gal
Fuel capacity3,790 lbs (oil)
Power sourcesteam
Starting effort57,511 lbf
Booster10,100 lbf
Power Plant
Driver diameter73 in
Boiler pressure210 psi
Expansion typesimple
Cylinderstwo, 28 x 30 in
Grate area75.7 sq ft
Firebox area355 sq ft
Tube heating area4,201 sq ft
Evaporative heating area4,556 sq ft
Superheater area1,162 sq ft
Total heating area5,718 sq ft
Calculated Values
steam locomotive
last changed: 01/2024

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