Class C1c (Locobase 1188)

Data from 1930 CMStP & P locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive collection.

Built by the railroad after Baldwin delivered four trial engines in 1901. More than half were gone by 1938, when the survivors were renumbered 1375-1395. These left service by 1949.

Class C2 (Locobase 1189)

Data from MILWRD 1930ca Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

Follow-ons to the C1s built a few years earlier. Milwaukee shops built 25 (7600-7624) in 1909-1910 while Baldwin delivered 50 (7100-7149) in 1910. The firebox heating surface included 29.3 sq ft of arch tubes. In late 1918, the Milwaukee modified the firebox of 7615 by replacing the four arch tubes with two Nicholson thermic syphons; see Locobase 8430 for the dramatic results.

Retirements began in 1936 and continued until 1954.

Class C2 - thermic syphon (Locobase 8430)

Data from E W Young, report to the Eleventh Annual Convention of the Master Boiler Makers Association (May 26-29, 1919), contained in the Official Proceedings (Harry D Vought, 1919).

Young reported on the results of a trial in which one of the C-2 Consolidations was modified solely by substituting two Nicholson Thermic Syphons for the 4 arch tubes installed in the rest of the class. It was the first test of the thermic syphon in any locomotive.

The General Boiler Inspector informed the gathering that the two locomotives used in the trial (7142 being the unaltered stable-mate to the 7615) had both recently been shopped. The same tender was used for both locomotives.

Running a 90-mile trial between Milwaukee and Portage, Wisconsin hauling an average train of 2,250 tons, each locomotive made 4 complete trips. At the end of the trial, 7615 had easily outdone the stalking iron horse in coal consumption (a 24.7% decrease), water use (11.1 percent lower), water evaporated per pound of coal (18% increase), "equivalent evaporation" per pound of coal (25.3% more). He added: "Engine 7615 was remarkably free from smoke at all times and discharged less cinders than engine 7142."

An additional difference prompted an intriguing comment. Young noted that the front-end temperature was lower in 7615 by 75 degrees, leading him to conclude the "...reduction ...indicated the firebox of engine 7615 absorbed a greater proportion of the total heat generated than did the firebox of engine 7142." What's more, the syphons proved more efficient, achieving an indicated evaporation "...approximately 50% higher than other heating surfaces in the same firebox, and 100 per cent. heigher than firebox heating surfaces of engine 7142."

Such trials would lead to a widespread acceptance of thermic syphons in locomotives that the railroads thought worth upgrading.

Class C3 (Locobase 9892)

Data from MILWRD 1930ca Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection. Works numbers were 32176, 32208 in November 1907.

Baldwin delivered this beefy pair to the I & WN, which was headquartered in Spirit Lake. They ran for decades, being reclassified and renumbered in 1916 when the I & WN came under Chicago, Milwaukee, St Paul & Pacific control.

The 7556 was sold to the Longview, Portland & Northern -- a 70-mile short line in Cowlitz, Oregon -- in 1935. The 7555 were retired in 1951.

Class C3 (Locobase 9893)

Data from MILWRD 1930ca Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection. Works numbers were 34525 in April 1910; 36276, 36295 in March 1911.

A repeat order for the I & WN, this quartet differed from the two earlier Consolidations (Locobase 9892) in having a 2" longer stroke for each cylinder. The 7558 was scrapped in October 1934. 7557 went much later in September 1949. The last 2 went in 1951 - 7559 in June and 7560 in December.

Class C5 (Locobase 1190)

Data from MILWRD 1930ca Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

Follow-ons to the C3s built a few years earlier. Milwaukee shops built 15 (7200-7204, 7240-7249) in 1912-1913 while Alco-Brooks delivered 35 (7205-7239) in 1912. Retirements began in 1945 and continued until 1954.