During World War II Union Pacific operated some of the most modern and powerful steam locomotives ever built. Among them were the famous “Big Boys,” the largest steam locomotives in the world, which were unique to Union Pacific. Working with them were the slightly smaller “Challenger” freight engines and the “800-class” high-speed passenger locomotives, as well as hundreds of older class steam engines. Although Union Pacific was among the first of the U.S. railroads to introduce diesel-powered streamlined passenger trains in the 1930s, the capabilities of these powerful steam locomotives made them the mainstay of UP freight operations throughout the war.
The efficiency of diesels eventually overwhelmed steam. Although steam engines were as powerful as diesels, and often faster, their huge appetite for fuel and water and the need for labor-intensive maintenance spelled their doom. Union Pacific quickly began buying diesel locomotives after the war and steam retreated to a stronghold in Wyoming, where the big engines ran their last miles in the late 1950s.
so what do you think which is stronger
I think the Big Boys were 7000 HP. UP never had a diesel that powerful.Thier Big Blow turbines were 8500 HP,later increased to 10,000HP.I don’t know of anything with more horsepower than those units.
Big Boy weighed 6000 pounds less than the first orders of the C&O 2-6-6-6 (772,000 pounds vs. 778,000 pounds). Big Boy’s boiler would fit inside that of the 2-6-6-6.
Big Boy’s maximum drawbar horsepower measured by dynamometer car was 6290 at 41 MPH.
2-6-6-6’s maximum drawbar horsepower measured by dynamometer car was 7498 at 45 MPH.
Big Boy’s maximum starting tractive effort was 135,375 pounds. N&W Y-6 starting tractive effort was 152,206 pounds before mid-1950s improvements; after those, it was 166,000 pounds. Virginian 2-10-10-2 starting tractive effort was 176,000 pounds. The Virginian and Erie triplex engines had starting tractive efforts right at 200,000 pounds but couldn’t sustain it; the 2-10-10-2 could sustain its starting power as could the N&W engine.
Sony, you need to read more Motive Power books and articles than those published by the Union Pacific.
How about the 8500 HP ‘Big Blow’ Turbines. Even the Navy finally figured out this was the way to go as most destroyers now have gas turbines. The Centenials built in 1969 were the first single unit diesels to equal the Big Boy. In a sense both had 2 engines on a single frame. Today the AC6000 exceeds it, but I wonder how the purchase costs compare in 2006 dollars.
The Big Boy vs. Allegheny debate has been around for a while. The consensus is that Lima designed a steam locomotive suitable for high-speed service but wound up being misused by C&O in low-speed coal service based on its tractive effort. Many have wondered what the Alleghenies would have accomplished if UP had them and used them in manifest freight service like the Challengers.
One thing I have said for a long time: The one thing the the UNION PACIFIC has done very well over the years is to manage their publicity and name recognition.
To the extent that the Colors[ Armour Yellow,etc], the UP Shield, and the pictures of Large locomotive power in Western settings have given the UNION PACIFIC a status of Iconic proportions in the RR fan circles. The UP colors and marques are instaneously recognizable.
The status of the “Big BOY” as the “biggest” is probably a product of good publicity and a highly competently designed machine. The prefomances and statistics of some other articulated big steam is well known: Allegheney’s, N&W 's " Y" classes, DM&IR’s ,also plus some others. Will lead to long sessions of argumentation, both pro and con in these threads. The corporate preformance of the UNION PACIFIC, as we have seen here in this forum has had mixed reviews.
Just my point of view.
Thanks, Sam