A total of 105 Challengers were built in five classes. They were nearly 122 ft (37 m) 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 4-8-8-4Big Boy 4014[1][2] and eventually donated to the Railroading Heritage of Midwest America in 2022.Cite error: A <ref> tag is missing the closing </ref> (see the help page). These were later sold to Clinchfield Railroad in 1947 and were renumbered as 670-675, where they formed the Clinchfield's Class E-3.[3]
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 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 is stored in Cheyenne, Wyoming, but has since been acquired by the Railroading Heritage of Midwest America (RRHMA), who have plans to restore the locomotive to operation once again.[4][5]
No. 3985 was restored in 1981 and used by Union Pacific on excursions until October 14, 2010, when mechanical problems forced it from service. It was officially retired in January 2020. The locomotive's tender, No. 25-C-311, has since April 2019 been assigned to the restored Big Boy, No. 4014. In 2022, No. 3985 was donated to the RRHMA, with plans to restore the locomotive to operation.[6][5]
