The reference for locomotives and railcars


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Union Railroad class U-108b
Duluth, Missabe & Iron Range class S7
United States | 1936 | 10 produced
No. 303 on a works photo
No. 303 on a works photo
Ron Ziel, „American Locomotives 1858 to 1949”

The Union Railroad was part of US Steel and was responsible for freight traffic between some of their plants and the main lines of several railroads in western Pennsylvania. The low speeds made it possible to achieve the largest possible adhesive weight without using a leading axle and without exceeding the length of the existing turntables. There was an additional booster on the first tender axle.

Since these locomotives were the only ones in North America with the 0-10-2 wheel arrangement, the name “Union” came about. The service at the Union Railroad ended in 1949 with the purchase of the first diesel locomotives. Nine of the ten locomotives were sold to the Duluth, Missabe and Iron Range, which also belonged to US Steel. They retired from service there between 1958 and 1961 and DM&IR number 604 is now on display in Greenville, Pennsylvania.

Axle config0-10-2 (Union) 
Gauge4 ft 8 1/2 in (Standard gauge)
Dimensions and Weights
Wheelbase32 ft
Fixed wheelbase22 ft
Total wheelbase67 ft 3 in
Service weight404,300 lbs
Adhesive weight343,930 lbs
Total weight644,300 lbs
Axle load70,000 lbs
Water capacity12,000 us gal
Fuel capacity28,000 lbs (coal)
Power sourcesteam
Estimated power4,000 hp (2,983 kW)
Optimal speed28 mph
Starting effort90,893 lbf
Booster17,150 lbf
Power Plant
Driver diameter61 in
Boiler pressure260 psi
Expansion typesimple
Cylinderstwo, 28 x 32 in
Grate area85.3 sq ft
Firebox area448.7 sq ft
Tube heating area4,359.3 sq ft
Evaporative heating area4,808 sq ft
Superheater area1,389 sq ft
Total heating area6,197 sq ft
Calculated Values
steam locomotive
last changed: 11/2023

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