Union Pacific Challenger
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The Union Pacific Challengers are a type of simple articulated 4-6-6-4
steam locomotive A steam locomotive is a locomotive that provides the force to move itself and other vehicles by means of the expansion of steam. It is fuelled by burning combustible material (usually coal, Fuel oil, oil or, rarely, Wood fuel, wood) to heat ...
built by
American Locomotive Company The American Locomotive Company (often shortened to ALCO, ALCo or Alco) was an American manufacturer that operated from 1901 to 1969, initially specializing in the production of locomotives but later diversifying and fabricating at various time ...
(ALCO) from 1936 to 1944 and operated by the
Union Pacific Railroad The Union Pacific Railroad is a Railroad classes, Class I freight-hauling railroad that operates 8,300 locomotives over routes in 23 U.S. states west of Chicago and New Orleans. Union Pacific is the second largest railroad in the United Stat ...
until the late 1950s. A total of 105 Challengers were built in five classes. They were nearly long and weighed 537 short tons (487 tonnes). They operated over most of the Union Pacific system, primarily in freight service, but a few were assigned to the ''Portland Rose'' and other passenger trains. Their design and operating experience shaped the design of the Big Boy locomotive type, which in turn shaped the design of the last three orders of Challengers. Two Union Pacific Challengers survive. The most notable is Union Pacific No. 3985, which was restored by the Union Pacific in 1981, then operated in excursion service as part of its heritage fleet program. Mechanical problems forced it out of service in October 2010; it was retired in January 2020 after the restoration of the
4-8-8-4 A 4-8-8-4 in the Whyte notation for the classification of steam locomotives by wheel arrangement, is a locomotive with a four-wheel leading truck, two sets of eight driving wheels, and a four-wheel trailing truck. Only one model of locomotives ha ...
Big Boy 4014 and eventually donated to the Railroading Heritage of Midwest America in 2022, where the locomotive is undergoing a second restoration. The only other surviving Challenger is UP No. 3977, which is on display in North Platte, Nebraska.


History


Description

The name "Challenger" was given to
steam locomotive A steam locomotive is a locomotive that provides the force to move itself and other vehicles by means of the expansion of steam. It is fuelled by burning combustible material (usually coal, Fuel oil, oil or, rarely, Wood fuel, wood) to heat ...
s with a 4-6-6-4 wheel arrangement: four wheels in the leading pilot truck to guide the locomotive into curves, two sets of six driving wheels, and four trailing wheels to support the rear of the engine and its massive firebox. Each set of driving wheels is driven by two steam cylinders. In essence, the result is two engines under one boiler. Union Pacific developed five types of Challengers: the "light" CSA-1 and CSA-2 classes and the "heavy" 4664–3, 4664–4, and 4664-5 classes. The railroad sought powerful locomotives that could handle mountain grades at high speeds. Previously, articulated locomotives had been limited to slow speeds by their design. Technical breakthroughs allowed the UP Challengers to operate with boiler pressure, something usually reserved for passenger locomotives like the FEF Series. They had drivers, mammoth wheels usually seen on passenger locomotives only because freight engines normally require the extra torque provided by smaller wheels. Speeds in excess of , while unheard-of on most other railroads using articulated steam locomotives, became commonplace on the Union Pacific. When the first Challengers entered service in 1936, on the UP's main line over the
Wasatch Range The Wasatch Range ( ) or Wasatch Mountains is a mountain range in the western United States that runs about from the Utah-Idaho border south to central Utah. It is the western edge of the greater Rocky Mountains, and the eastern edge of the Gr ...
between Green River and Ogden, the locomotives had problems climbing the steep
grades Grade most commonly refers to: * Grading in education, a measurement of a student's performance by educational assessment (e.g. A, pass, etc.) * A designation for students, classes and curricula indicating the number of the year a student has reach ...
. For most of the route, the maximum grade is 0.82% in either direction, but the climb eastward from Ogden, into the Wasatch Range, reached 1.14%. Hauling a freight train demanded
double heading In railroad terminology, double heading indicates the use of two locomotives at the front of a train, each operated individually by its own crew. The practice of triple-heading involves the use of three locomotives. The practice of multi-head ...
and helper operations, and adding and removing helper engines slowed operations. Those limitations prompted the introduction of the Big Boy in 1941, as well as a redesign of the last three orders from 1942 to 1944. Using the experience from the Big Boy, UP chief mechanical engineer, Otto Jabelmann, redesigned the last three orders of Challengers in 1941. The result was a locomotive in working order weighing some accompanied by a tender weighing when 2/3 loaded. Calculated tractive effort is . From 1941, the Challengers were intended to speed up freight operations on the grades across Wyoming; the Wasatch Range climb east from Ogden was taken over by unassisted Big Boys.


Construction

The 105 locomotives were ordered in five batches: the first two of light Challengers, and the final three of heavy Challengers. The Challengers, along with the Big Boys, were introduced just as traffic was surging in preparation for American entry to
World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
. As part of
Union Pacific The Union Pacific Railroad is a Class I freight-hauling railroad that operates 8,300 locomotives over routes in 23 U.S. states west of Chicago and New Orleans. Union Pacific is the second largest railroad in the United States after BNSF, ...
's fourth order in 1943,
ALCO The American Locomotive Company (often shortened to ALCO, ALCo or Alco) was an American manufacturer that operated from 1901 to 1969, initially specializing in the production of locomotives but later diversifying and fabricating at various time ...
built thirty-one locomotives for Union Pacific using the same specifications. However, the
War Production Board The War Production Board (WPB) was an agency of the United States government that supervised war production during World War II. President Franklin D. Roosevelt established it in January 1942, with Executive Order 9024. The WPB replaced the Su ...
diverted six locomotives after completion to the
Denver and Rio Grande Western Railroad The Denver and Rio Grande Western Railroad , often shortened to ''Rio Grande'', D&RG or D&RGW, formerly the Denver & Rio Grande Railroad, was an American Class I railroad company. The railroad started as a narrow-gauge line running south fr ...
via a lease through the War Department's Defense Plant Corporation. Locomotives 3900-3905 formed the Rio Grande's Class L-97. These were later sold to
Clinchfield Railroad The Clinchfield Railroad was an operating and holding company for the Carolina, Clinchfield and Ohio Railway . The line ran from the coalfields of Virginia and Elkhorn City, Kentucky, to the textile mills of South Carolina. The 35-mile segmen ...
in 1947 and were renumbered as 670–675, where they formed the Clinchfield's Class E-3; these six Challengers were eventually retired in 1953.


Preservation

Only two Challengers survive, both from the 4664-4 order built in 1943. No. 3977 is on static display in North Platte, Nebraska. No. 3985 was restored to operating condition by
Union Pacific The Union Pacific Railroad is a Class I freight-hauling railroad that operates 8,300 locomotives over routes in 23 U.S. states west of Chicago and New Orleans. Union Pacific is the second largest railroad in the United States after BNSF, ...
in 1981 and used in excursion service until mechanical problems sent it back into storage in October 2010. It was officially retired in January 2020 and stored in
Cheyenne, Wyoming Cheyenne ( or ) is the List of capitals in the United States, capital and List of municipalities in Wyoming, most populous city of the U.S. state of Wyoming. It is the county seat of Laramie County, Wyoming, Laramie County, with 65,132 reside ...
, but has since been donated to the Railroading Heritage of Midwest America (RRHMA) in Little Silvis Shops in
Silvis, Illinois Silvis is a city in Rock Island County, Illinois, Rock Island County, Illinois, United States. It is part of a larger metropolitan area known as the Quad Cities. The Quad Cities Metropolitan Area is situated across four counties in Illinois and Io ...
, where the locomotive is now being restored to operation once again.


See also

*
Union Pacific Big Boy The Union Pacific Big Boy is a type of simple articulated locomotive, articulated 4-8-8-4 steam locomotive manufactured by the American Locomotive Company (ALCO) between 1941 and 1944 and operated by the Union Pacific Railroad in revenue service ...
* Union Pacific FEF series *
Norfolk and Western A class The Norfolk and Western "A" was a class of 43 2-6-6-4 simple articulated locomotive, articulated steam locomotives built by the railroad's own Roanoke Shops between 1936 and 1950 and operated until the late 1950s. The locomotives hauled fast and h ...
* Chesapeake and Ohio class H-8


References


Bibliography

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Further reading

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External links


Union Pacific Steam Shop
Information on locomotives and excursion schedules.

- photos and additional information {{Whyte types Union Pacific Railroad locomotives ALCO locomotives Simple articulated locomotives Standard-gauge locomotives of the United States Railway locomotives introduced in 1936 Steam locomotives of the United States Locomotive designs used by multiple railways