Union Pacific No. 4006

Union Pacific 4006 is a four-cylinder articulated 4-8-8-4 Big Boy-type steam locomotive owned by the Union Pacific Railroad. This locomotive was built by Alco in 1941 along with the other Big Boy locomotives to address the problems concerning the preceding 4-6-6-4 Challenger class locomotives. 
The locomotive was used to haul fast freight on heavy grades, particularly on the Ogden-Wasatch district between Utah and Wyoming, but also over Sherman Hill just west of Cheyenne, WY. It ran in service until July 21, 1959, when it was retired along with the other Big Boy Locomotives. 
Two years later, in 1961, it was donated to the National Museum of Transportation, in St Louis, MO, where it remains on public display today.
==Trivia== 
*4006 is in the most games of any big boys, three games to be exact.
*The locomotive's bell used to be air-rung like the other Big Boys, but it was converted to hand-rung sometime while on display, making 4006 the only Big Boy to have a hand-rung bell.
==Gallery ==
C95D77AA-D21E-4A0C-ABEB-B176B9ED4237.jpeg
Big Boy 4006.jpg
Up4006andUp6944.jpg
Up4006builderplate.jpg
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Category:Union Pacific locomotives
Category:Steam locomotives
Category:Tender locomotives
Category:American locomotives
Category:Built in 1941
Category:4-8-8-4 locomotives
Category:4-8-8-4 steam locomotives
Category:Eight-coupled locomotives
Category:Articulated locomotives
Category:ALCO locomotives
Category:Museum Of Transportation Engines
Category:Freight locomotives
Category:Locomotives
Category:American steam locomotives
Category:United States
Category:Union Pacific Big Boy
Category:Preserved locomotives
Category:Preserved steam locomotives
Category:Standard gauge locomotives of the United States
Category:Locomotives featured in media