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The reference for locomotives and railcars

Union Pacific classes MT-1 and MT-2

United States 1922 60 produced
MT-1 No. 7857 in October 1955 at Cheyenne, Wyoming Robert M. Hanft / collection Taylor Rush

The only 4-8-2 Mountain locomotives ever operated by the Union Pacific were the classes MT-1 and MT-2, which were nearly identical apart from their firing method. The first 40 MT-1 were built in 1922 by ALCO, followed by 15 more in 1923 which weighed 3,000 pounds less. These were all coal-fired and had a tender that held 12,000 gallons of water and 20 tons of coal. Five MT-2 delivered in 1924 were oil-fired and had tenders with 15,000 gallons of water and 5,480 gallons of oil.

These locomotives were used to haul important passenger trains over long distances. They ran distances of 500 to 700 miles without major stops. Later, many were fitted with a partial casing. Only 7002 was totally streamlined and got roller bearings on all axles and the rods. It was used to haul the all-Pullman “Forty-Niner” when it was found out that early diesels could not keep up the schedule between Chicago and San Francisco. By 1956, all MT-1 and MT-2 locomotives had been scrapped.

Streamlined MT-1 No. 7002 at North Platte, Nebraska collection Taylor Rush

Technical data

General

Property MT-1 MT-2
Built 1922-1923 1924
Manufacturers ALCO
Wheel arrangement 4-8-2 (Mountain)
Gauge 1,435 mm (Standard gauge)

Dimensions and weights

Property MT-1 MT-2
Wheelbase 12.57 m
Total wheelbase 24.37 m
Service mass 157.9 t 158.9 t
Adhesion mass 105.2 t 105.7 t
Total mass 265.6 t 287.9 t
Rigid wheelbase 5.97 m
Axle load 26.3 t 26.4 t
Water capacity 45,425 l 56,781 l
Fuel capacity 18.1 t (coal) 20,744 l (oil)

Boiler

Property MT-1 MT-2
Grate area 7.804 m²
Firebox surface 35.489 m²
Tube heating surface 426.611 m²
Evaporative heating surface 462.1 m²
Superheater surface 115.386 m²
Total heating surface 577.5 m²

Power plant

Property MT-1 MT-2
Driver diameter 1,854 mm
Boiler pressure 13.8 bar
Expansion type simple expansion
Cylinders two, 737 x 711 mm

Power

Property MT-1 MT-2
Power source steam
Estimated power 2,498 kW (3,396 PS) 2,610 kW (3,549 PS)
Starting effort 243.9 kN

Calculated values

Property MT-1 MT-2
Factor of adhesion 1 : 4.23 1 : 4.25
Optimal speed 63 km/h 66 km/h
Power-to-weight ratio 15.8 kW/t 16.4 kW/t
Heating Surface Equivalent 870.3 m²
Cylinder volume/HSE 1 : 696.46
Adhesive weight/Total 1 : 1.50
Tractive force/Heating surface 1 : 8.82
Grate area/Heating surface 1 : 74.00
Firebox/Tube surface 1 : 12.02
Total/Superheater 1 : 4.00
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