Union Pacific Challenger
Encyclopedia
Built between 1936 and 1943, the Challengers were nearly 122 feet long and weighed more than one million pounds. Articulated like their big brother, the Union Pacific Big Boy
, the Challengers had a 4-6-6-4 wheel arrangement. They operated over most of the Union Pacific system, primarily in freight service, but a few were assigned to passenger trains operating through mountain territory to California and Oregon. The 105 locomotives were built specifically by ALCO
for Union Pacific having drawn on much of the Big Boy's experience.
The name Challenger was given to steam locomotives with a 4-6-6-4 wheel arrangement. This means that they have four wheels in the leading "pilot" truck, which helps guide the locomotive into curves; two sets of six "driving" wheels, and finally, four "trailing" wheels, which support the rear of the engine and its massive firebox. Each set of driving wheels has its own steam cylinder. In essence, the result is two engines under one boiler.
Two examples survive today: Union Pacific 3985
, used for excursion services by Union Pacific and Union Pacific 3977
, on static display in North Platte, NE.
Union Pacific Big Boy
Big Boy was the name of the Union Pacific Railroad's 4000-class 4-8-8-4 articulated steam locomotives, built between 1941 and 1944 by American Locomotive Company...
, the Challengers had a 4-6-6-4 wheel arrangement. They operated over most of the Union Pacific system, primarily in freight service, but a few were assigned to passenger trains operating through mountain territory to California and Oregon. The 105 locomotives were built specifically by ALCO
American Locomotive Company
The American Locomotive Company, often shortened to ALCO or Alco , was a builder of railroad locomotives in the United States.-Early history:...
for Union Pacific having drawn on much of the Big Boy's experience.
The name Challenger was given to steam locomotives with a 4-6-6-4 wheel arrangement. This means that they have four wheels in the leading "pilot" truck, which helps guide the locomotive into curves; two sets of six "driving" wheels, and finally, four "trailing" wheels, which support the rear of the engine and its massive firebox. Each set of driving wheels has its own steam cylinder. In essence, the result is two engines under one boiler.
Two examples survive today: Union Pacific 3985
Union Pacific 3985
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. The UP 3985 locomotive was built in 1943 by the American Locomotive Company of Schenectady, New York...
, used for excursion services by Union Pacific and Union Pacific 3977
Union Pacific 3977
Union Pacific 3977 or UP 3977 is a 4-6-6-4 steam locomotive originally owned by Union Pacific Railroad. Its counterpart, Union Pacific 3985, is the largest operating steam locomotive in the world. 3977 was donated to the City of North Platte, Nebraska for display on October 19, 1968...
, on static display in North Platte, NE.
External links
- Union Pacific Steam Shop Information on locomotives and excursion schedules.
- UP 3985 Challenger, Steam Locomotive - photos and additional information
- Union Pacific locomotive classes Information on the Challenger and other Union Pacific locomotives