by Emmett R Smith
Consider the 1914 Erie RR 2-8-8-8-2 Matt Shay
steamlocomotive dot com
As the reader will perceive, the haggle over the “most powerful” steam locomotive of the last steam age is…endless. Heretofore I have come down on the side of C & O’s 2-6-6-6 Allegheny as opposed to Union Pacfic’s “Big Boy” 4-8-8-4s. This is, too, even though the UP engines were both heavier and had more “tractive effort,” or pulling power from rest at the driver-railface. In this I have been content to follow the lead of steamlocomotive dot com postings:
But, on pp 100-1 of Edwin P Alexander’s 1950 book, American Locomotives: A Pictorial Record Of Steam Power, Alexander gives these numbers for the four Baldwin-built 2-8-8-8-2s of 1914:
Cylinders — 2 high pressure and 2 low, @ 36″ and 32″ diameters. Unfortunately, Alexander does not give the stroke which is vital to the TE (tractive effort) calculation, TE = cP(d-squared)s/D, in which c = .85.
Weight, total — 864,400 lbs
Steam pressure — 210 lb psi
Fuel — 16 tons
Water — 11,600 gal
Driver diameter — @ 63″
And! these three Erie P1s (a fourth, #700, was built for Virginian RR) come in with the highest pulling power of any late-modern steam locomotive in North America.
Tractive Effort (TE) — 160,000 lbs
However, twenty-seven years before the Big Boys and the Alleghenys, the Erie engines didn’t steam well enough to supply the consistent cylinder pressure needed, and the couplers on the railroad gondolas and other cars of a generation earlier could not take the gaff! Additionally, at http://www.steamlocomotive.com/articulated/eriep1.shtml it is written:
“The triplexes were used with some success on the Erie Railroad but were not without problems. They were too large for Erie’s own shops. Major repairs were performed in the Lehigh Valley shops at Sayre, PA. Another major problem with the triplexes was that the steam supply was inadequate for speeds past 10mph on the Erie and 5 mph on the Virginian. Part of the problem was that the tender motor unit exhausted to the air, reducing the amount of draft available to the firebox. Another problem was the “variable adhesion” of the tender motor unit. As the coal and water was consumed, the weight on drivers was reduced, thus reducing the factor of adhesion on the tender unit.”
Still, the TE figure of 160,000 pounds IS pretty hair raising! Not until 1948 would the Norfolk & Western Railway’s 2-8-8-2 Y6a steam locomotives come in even close, at a simple expansion pressure of 152,206 pounds.
[Emmett R Smith all rights reserved 9 June 2009]