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Built in 1943 by the American Locomotive Company of Schenectady, New York, Union Pacific 3985 or UP 3985 is a four-cylinder simple articulated 4-6-6-4 Challenger-type steam locomotive owned by Union Pacific Railroad. It is currently the largest operational steam locomotive in the world. Designed by UP chief mechanical engineer Otto Jabelmann in 1941, 3985 was part of the second order of this second version of the Challenger. The design drew heavily on recent experience with the enormous 4-8-8-4 Big Boy locomotives, and resulted in a locomotive in working order weighing some 317 short tons accompanied by a 2/3 loaded tender weighing 174 short tons. Tractive effort was 97,350 lbf. The initial purpose of the Challenger class was to speed up freight operations east and west of the Wasatch grades in Utah and western Wyoming. The Wasatch itself was to be conquered by the Big Boys without helpers. The Challengers and Big Boys arrived on the scene just as traffic was ramping up preparatory to the belated American participation in World War II.
3985 was originally retired about 1960 and after many years of storage in the Cheyenne, Wyoming, roundhouse it was placed on outdoor display beside the Cheyenne depot in 1975. Later a group of UP employee-volunteers overhauled it, beginning in 1979, and returned it to operable condition in early 1981. Originally a coal-burner, to prevent lineside grass fires it was successfully converted to oil firing in 1990. Stationed at Cheyenne with other equipment in the UP's heritage collection, it is currently used for excursion trains and occasionally mainline freight on ferry moves. At the moment (2007) it is in the maintenance shop at Cheyenne and is undergoing necessary repairs for service in 2008. It is one of only two of the original 105 Union Pacific "Challenger" types in existence, the other being UP 3977 on static display in North Platte, Nebraska.
[edit] Sources
- Ehernberger, "Challenger Portraits", Challenger Press, Cheyenne, WY, 1993.
- Kratville, "The Challenger Locomotives", Kratville Publications, Omaha, NE, 1980.
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