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The American Locomotive Company (ALCO) 4000 Class, better known as the Union Pacific Big Boy, is a 4-8-8-4 simple articulated type of steam locomotive built by the American Locomotive Company (ALCO) specially for the Union Pacific Railroad (UP) between 1941 and 1944. They are the most iconic and best-known steam locomotives on the Union Pacific. Of the twenty five Big Boys that were built, eight of them survive in preservation today, those being Nos. 4004, 4005, 4006, 4012, 4014, 4017, 4018, and 4023. Today, No. 4014 is the only surviving Big Boy in operating condition, as well as the only Big Boy to ever operate in excursion service.

UP Big Boy Controls

The Controls for the Union Pacific Big Boy

History[]

During World War II in the 1940s, railroads in the United States were in dire need of larger steam locomotives to deliver long and heavy trains (which became longer and heavier due to the stock market boom as a result of the US recovering from the Great Depression; aside from having more materials needed to built vehicles and weapons to supply troops in combat), to whom the economy skyrocketed after the Great Depression, and many companies relied on trains to deliver their goods.

Hence, railroads like the Union Pacific needing larger locomotives to haul such long and heavy freight trains through their long routes. Which meant the request from ALCO to design a much larger version of their "Challenger" type of 4-6-6-4 articulated steam locomotive for conventional horsepower.

The 4000 Class dominated the steam locomotive market by having less wheels and more power and length compared to other Mallet types of steam locomotives (such as the "Erie Triplex" Class from the Erie Railroad), which meant that they were easier to maintain, yet they were very expensive to operate because of how much water and coal they consumed, as well as how much time, effort, and money used to mold the metal and other materials for the steaming giants (yet, more purchases led to ALCO's large earnings).

Once they were purchased by the Union Pacific; and when they were still in production, most railfans, train enthusiasts, locomotive builders, and railroad employees nicknamed the giant type of steam locomotive the "Big Boy". (yet the name; however, was rumored to have began as a simple nickname stenciled in the boiler of an ALCO employee during the construction of the first one built in early-1941). But their times hauling trains on the Union Pacific system unfortunately came to an end during the 1950s, when the GE GTEL Gas Electric Turbine super-powered diesel turbine locomotives began to replace the Big Boys and Challengers during the end of the Steam Era, however in their last few years, they were put onto reserve service until their official decommission in 1962. Seventeen engines succumbed to the cutter's torch; surprisingly - for such a small number built - eight of the 25 beasts built survive, all which are currently on static display in various museums throughout America, except for 4014, which has been restored to operating condition.

Locomotive Page[]

  1. Union Pacific No. 4000
  2. Union Pacific No. 4001
  3. Union Pacific No. 4002
  4. Union Pacific No. 4003
  5. Union Pacific No. 4004
  6. Union Pacific No. 4005
  7. Union Pacific No. 4006
  8. Union Pacific No. 4007
  9. Union Pacific No. 4008
  10. Union Pacific No. 4009
  11. Union Pacific No. 4010
  12. Union Pacific No. 4011
  13. Union Pacific No. 4012
  14. Union Pacific No. 4013
  15. Union Pacific No. 4014
  16. Union Pacific No. 4015
  17. Union Pacific No. 4016
  18. Union Pacific No. 4017
  19. Union Pacific No. 4018
  20. Union Pacific No. 4019
  21. Union Pacific No. 4020
  22. Union Pacific No. 4021
  23. Union Pacific No. 4022
  24. Union Pacific No. 4023
  25. Union Pacific No. 4024
UP Big Boy 2

Number 4012 at the Steamtown National Historic Site in Scranton, Pennsylvania.

Trivia[]

  • Apparently, the original name of the Big Boy was supposed to be "Wasatch". However, as the story goes, an unknown worker at ALCO chalked "Big Boy" on the boiler of No. 4000, unintentionally christening it with the name these locomotives go by.
  • The Big Boy has more steam valve controls than any other type of steam locomotive.
  • Most average people and train enthusiasts often confuse the Challenger and Big Boy for one another. The main differences are the position of the boiler number plate, and the wheel arrangements.
  • Big Boys were rarely occasionally assigned to passenger service.
  • Most crew members who drove Big Boys often used auger drills to drill the coal stored in the tender because of how long it often sat due to the size of the tender. Hence, coal being refilled every month or so.
  • The Japanese anime TV series "Galaxy Railways" features a space train named Big One, a very stylized depiction of a Big Boy.
  • The Big Boys' smokestack were actually two smokestacks combined and covered with smoke deflectors.
  • On April 27, 1953, No. 4005 derailed due to a misaligned switch. Thankfully, the locomotive was repaired and returned to service. It is the only Big Boy to have ever been involved in a serious accident.
  • Only two Big Boys have ever been converted from burning coal to burning oil, those being Nos. 4005 and 4014. No. 4005 was converted to burn oil in December 1946 as part of an experiment due to a coal strike, but the conversion wasn't that much of a success and it was soon after converted back to burn coal in March 1948. No. 4014 was converted to burn oil during its restoration to operating condition for excursion service, which was completed in May 2019, just in time for the 150th anniversary of the Driving of the Golden Spike in Promontory Summit, Utah.

Videos[]

Gallery[]

List of Union Pacific Big Boy Locomotives
Real-Life Members: 4000400140024003400440054006400740084009401040114012401340144015401640174018401940204021402240234024
Fallen: 400040014002400340074008400940104011401340134015401640194020402140224024
Preserved: 40044005400640124014401740184023
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