The Union Pacific Big Boy is a class of large articulated steam locomotives built for Union Pacific Railroad beginning in 1941, designed to haul heavy freight over the mountain grades of Wyoming and Utah. At roughly 132 feet long and over a million pounds, the class ranks among the largest and most powerful steam locomotives ever built, and one preserved example, No. 4014, has operated in excursion service after restoration.
Facts
SignificanceThe largest and most powerful steam locomotive ever built, designed to haul heavy freight over mountainous terrain without helper locomotives. 1 Manufacturer or BuilderAmerican Locomotive Company (ALCO) 1 FAQs
Do any Big Boy locomotives still exist and can one still run?
Eight survive and only No. 4014 operates; the other seven are on public display.
Eight of the twenty-five Big Boys built for Union Pacific still exist, and only one is in operation: Union Pacific's No. 4014. It was retired in December 1961 after traveling 1,031,205 miles, was reacquired by Union Pacific in 2013 from the RailGiants Train Museum in Pomona, California, and returned to service in May 2019 for the 150th anniversary of the transcontinental railroad's completion. The seven others are on public display in St. Louis, Missouri; Dallas, Texas; Omaha, Nebraska; Denver, Colorado; Scranton, Pennsylvania; Green Bay, Wisconsin; and Cheyenne, Wyoming.
How could a locomotive about 133 feet long get around curves?
The frame is hinged, or articulated, so the long locomotive can negotiate curves.
Union Pacific describes the Big Boy as articulated: because of their great length, the frames of the Big Boys are hinged so that the locomotive can negotiate curves. The wheel arrangement is 4-8-8-4, meaning four guiding wheels at the front, two sets of eight driving wheels, each set belonging to its own engine, and four trailing wheels under the rear of the locomotive.
Connections
In the Other Atlases
Manufactured By
Also in Business Atlas: the manufacturer of this subject.
Sources
1. Wikipedia: Union Pacific Big Boy
WikipediaDesign section
The 25 Big Boy locomotives were built to haul freight over the Wasatch Range between Ogden, Utah, and Green River, Wyoming.
In Group: American Main-Line Steam Locomotives, Lead sentence
The Union Pacific Big Boy is a type of simple articulated 4-8-8-4 steam locomotive manufactured by the American Locomotive Company (ALCO) in Schenectady, New York, between 1941 and 1944 and operated by the Union Pacific Railroad in revenue service until July 1959.
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