Soo Line B-4 class

The Soo Line B-4 class were 0-6-0 steam locomotives constructed for the Minneapolis, St. Paul and Sault Ste. Marie Railway (Soo Line) by the American Locomotive Company. Six (#344–349) were built at their Schenectady plant in 1915, with a further five (#350–354) being constructed by their Brooks plant in Dunkirk, New York, in 1920.

Soo Line B-4 class
Soo Line No. 346 locomotive in Tracy, MN
Type and origin Power type Steam Builder American Locomotive Company Build date 1915 (6), 1920 (5)
Specifications Configuration: ​  • Whyte 0-6-0  • UIC C h2 Gauge 4 ft 8+1⁄2 in (1,435 mm) Driver dia. 51 in (1,295 mm) Wheelbase Loco: 11 ft 6 in (3.51 m) Length 58 ft 10+3⁄8 in (17.94 m) Width 10 ft 5 in (3.18 m) Height 15 ft 3+1⁄2 in (4.66 m) Axle load 51,500 lb (23.4 tonnes) Loco weight 151,000 lb (68.5 tonnes) Tender weight 102,900 lb (46.7 tonnes) Fuel type Coal Fuel capacity 16,000 lb (7.3 tonnes) Water cap. 5,000 US gal (19,000 L; 4,200 imp gal) Boiler pressure 180 lbf/in2 (1.24 MPa) Cylinders Two, outside Cylinder size 20 in × 26 in (508 mm × 660 mm) Valve gear Walschaerts
Performance figures Tractive effort 31,200 lbf (138.78 kN)
Career Operators Minneapolis, St. Paul and Sault Ste. Marie Railway (Soo Line) Class B-4 Number in class 11 Numbers 344–354 Preserved #346; #353 Disposition Two preserved, of which one is operational

They were the last, and largest design of purpose-built switch engines that the Soo Line owned, any heavier switching duties were performed by down-graded 2-8-0 freight engines. All were still on the active roster in May 1953,[1] but all had been retired by the end December 1954 when the railroad completed its dieselization.

Two are preserved[2] - #346 from the first batch, which is displayed at the Wheels Across the Prairie Museum at Tracy, Minnesota, as Dakota, Minnesota and Eastern #9, and #353 from the second batch, which is operational and gives free rides annually at the Western Minnesota Steam Thresher's Reunion, Rollag, Minnesota.