"Zeppelins of the Rails" was the unlikely epithet the Chicago & North Western tried to pin on the 35 Class H 4-8-4s delivered by Baldwin Locomotive Works in 1929. Weighing in at 498,000 pounds minus tender, these behemoths when introduced were the heaviest non-articulated locomotives in service in North America. The locomotive's main frame, including the cylinders, was a single steel casting 58 feet 3 inches long and weighing 73,000 pounds. Boasting cylinder dimensions of 27x32 inches, with a working boiler pressure of 275 pounds and 76-inch drivers, these engines produced 71,000 pounds of tractive force augmented by a booster that raised the total to 84,200 pounds.
Like other North American locomotives that were among the first to be have a four-wheel trailing truck, the Class H locomotives were designed with an outside-cradle frame, in which the rear portion divides to the sides of the locomotive to allow for the deeper firebox and larger truck casting. This photo of No. 3035, which I found in an antique shop, was taken by C. C. Grayson of Longview, Texas. It shows the Class H design in its original configuration. A 1940 rebuilding gave these locomotives disc drivers and roller bearings on all axles, and 24 were rebuilt in the late 1940s with new frames, cylinders, fireboxes, and other improvements and reclassified as H-1. No. 3035, last of the class H, was among those selected for rebuilding; a photo of it in its later stage appears in George H. Drury's Guide to North American Steam Locomotives (Kalmbach, 1993).
For a photo of No. 3024 of this class as displayed at the Century of Progress Exposition in Chicago in 1934, visit my 1942 C&NW Historical Booklet web site.