Big Boy at 85:
85 years ago, the first batch of Big Boys were rolled out of the American Locomotive Company's shops in Schenectady, New York. While not the record holding longest, most powerful, or heaviest locomotive, pound-for-pound they are one of the largest steam locomotives ever built.
Between 1941 and 1944, 25 Big Boy locomotives were built exclusively for the Union Pacific Railroad. Prior to the Big Boys, Union Pacific operated Challenger locomotives over their main line between Green River, Wyoming and Ogden, Utah. Despite the great size of the 4-6-6-4 Challengers, even these mighty locomotives needed help pulling trains over the Rockey Mountains. The railroad sought more power, enough to pull a train over the mountains alone.
A Union Pacific design team worked together with American Locomotive Company (ALCO) to re-examine the Challenger's design. To achieve UP's goal of a larger locomotive, four key design changes were made:
1. The size of the firebox was increased to 150 sq ft.
2. The boiler pressure was raised to 300 psi.
3. The new locomotives would be a 4-8-8-4 wheel arrangement. 4 leading wheels to guide the locomotive, two sets of 8 drive wheels, and 4 wheels under the cab to support the firebox.
4. The drive wheels were reduced from 69 inches in diameter to 68 inches.
Weighing in at 600 tons, the Big Boys were rated to pull a 5-mile train alone and designed to smoothly and safely reach speeds of 80 mph. On average, Big Boys would pull 3-mile trains, getting their best tractive effort (or peak horsepower) at 41 mph. The tender of the locomotive carried 25 tons of coal and 24,000 gallons of water. Big Boys could burn through half of their coal and water supply within 1 hour.
Originally to be named "Wasatchs" after the Wasatch mountain range, the locomotives earned their nickname after an unknown ALCO employee wrote "Big Boy" in chalk as a joke on the smokebox door of engine 4000, the first of the 4-8-8-4 design.
Although of a daunting size and complete with a complex backhead, Big Boys were highly regarded by train crews. Engineers and firemen found the locomotives to be sure-footed, rarely slipping on the railroad's steep mountain climbs. Some even claimed that they were even more user-friendly than other locomotives in UP's fleet. Operating between Cheyene, Wyoming and Ogden, Utah, Big Boys became a favorite of train crews and the public alike.
Union Pacific operated their Big Boys until their last revenue service run on July 21, 1959. They remained stored in operable service until 1962. Of the 25 built, 8 remain in preservation, including Steamtown NHS' very own UP 4012.
In 2019, Union Pacific finished their full restoration of Big Boy 4014 to celebrate the 150th anniversary of the first Transcontinental Railroad's completion.
Image: Union Pacific Big Boy 4000 in Binghamton, NY on its way west to Wyoming for delivery to Union Pacific, 1941.
ALT Big Boy is posed for a promotional photo in a railyard. The locomotives number boards above the front have not been placed.