Between 1905 and 1906, twenty-eight Consolidation type (2-8-0) cross compound locomotives were built for the Minneapolis, St. Paul & Sault Ste Marie (also known as the Soo Line) by Alco at its Schenectady, NY, works
(#445-#472). #451 was delivered in 1905.
Classified F-9, these comprised the largest order of Consolidations made by the Soo Line, adding to the forty-five cross compounds already purchased between 1893 and 1903 (you can see one of the earlier F-8 class on the SOO #440 page of this website).
All fifty-one of these cross-compounds were later
simpled and superheated, removing one hundred and
fifty-four small tubes in favour of twenty-eight
superheater flues. By the time the F-9s were taken in for superheating in 1919, they had already lost their one
35” x 34” low pressure cylinder. At 22½” x 34”, the new cylinders were slightly smaller than the original 23” x 34” ones. At the same time, the Stephenson valve gear was replaced with Walschaert and the boiler pressure
dropped from 210 psi to 170 psi, although in later service, some (including #451) had their boiler pressure returned to 200 psi.
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The changes to the F-9s reduced the engine weight by 13,000 lbs from 210,500 lbs to 197,800
lbs, and weight on the 63” drivers from 174,000
lbs to 169,800 lbs. With a 158 sq ft grate, 46.89 sq
ft firebox and total heating surface of 2,574 sq ft, including 327 sq ft superheating, they delivered 39,479 lbs tractive effort, an additional 3,888 lbs compared to the original cross compounds'
A test carried out on one of the rebuilt locomotives demonstrated that, per thousand ton miles, it consumed 13.9% less coal.