C&O No.1604 "Allegheny"
Name: C&O No.1604
Railroad of Record: Chesapeake & Ohio Railway Type of Locomotive: 2-6-6-6 Allegheny (simple articulated)
Class: C&O Class H-8
Builder No.: 7824
Manufactured by: Lima Locomotive Works
Date Built: December 1941
Locomotive Weight: 389 tons
Driver Diameter: 67 inches
Cylinders: 22 ½ x 33 inches (4)
Tractive Effort: 110,200 lbs
Maximum Drawbar Horsepower: 7498 (peak), 7325 (sustained)
By the 1940s, the Chesapeake & Ohio Railway (C&O) and Lima Locomotive Works developed a new type of steam locomotive that could tackle the tough Allegheny Mountain grades more efficiently than the current 2-6-6-2s and 2-8-8-2s. The new locomotive had a 109-inch wide boiler, which was 2 inches larger than the "Big Boy" locomotive and a fire box that was so large it required a six-wheel trailing truck to support it. The locomotive only had six axles, instead of the usual eight. This new 2-6-6-6 locomotive was known as the "Allegheny" after the mountains it was designed to conquer.
The "Allegheny" locomotives were quite successful pulling slow coal drags through the mountains, but they could also travel as fast as 60 miles per hour pulling occasional passenger trains. By the end of 1948, there were 60 of the 2-6-6-6 locomotives on the C&O's roster.
The No. 1604 is a simple articulated locomotive. An articulated locomotive is a locomotive that has two sets of cylinders each driving a separate set of wheels, which are mounted in two separate frames connected by a pivot joint. The boiler sits on the leading frame and is attached to the second frame. The lead frame can swivel radically at the pivot joint. This permits the locomotive to negotiate curves. All types of articulated locomotives are called "Mallets." On the simple expansion articulated locomotive, all cylinders receive steam at boiler pressure (high pressure steam).
Beginning in 1952, the "Allegheny" was being replaced with new efficient diesel locomotives. The No. 1604 was one of two "Alleghenies" that escaped from scrapping. In 1986, the No. 1604 was transferred to the Baltimore & Ohio Railroad Museum. The other "Allegheny," No. 1601, resides at the Henry Ford Museum in Dearborn, Michigan. The "Allegheny" locomotive series was considered one of the heaviest and most powerful American-built steam locomotives ever built.