World’s Largest Operating Steam Locomotive Reminds Thousands of Days Gone By

On Board No. 3985.– Thousands of people line the route as Union Pacific Railroad’s “Challenger” No. 3985, the world’s largest operating steam locomotive, travels from Cheyenne, Wyo., to St. Paul, Minn., and back, to celebrate railroad history and heritage.

The five-state, 1,700-mile tour celebrates railroad heritage as the 65-year-old locomotive travels from its home base in Cheyenne across the railroad history-rich Midwest.

“We are proud to have No. 3985 on display during North Platte’s Rail Fest celebration as well as in St. Paul. These two cities are steeped in railroad history,” said Steve Lee, Union Pacific’s manager – operating practices and locomotive engineer.

Union Pacific’s “Challenger” No. 3985, built in 1943, is an articulated locomotive with a “hinged” frame that allows it to negotiate curves. It is 122 feet long, weighs more than 1 million pounds, has 6-foot diameter drive wheels and can reach a top speed of 70 miles per hour. No. 3985 was built for fast freight service. It was retired in 1959, but UP employee volunteers restored it to running condition in 1981 for special service.

The name Challenger was given to steam locomotives with a 4-6-6-4 wheel arrangement. This means that they have four wheels in the leading “pilot” truck, which helps guide the locomotive into curves; two sets of six “driving” wheels, and finally, four “trailing” wheels, which support the rear of the engine and its massive firebox. Each set of driving wheels has its own steam cylinder. In essence, the result is two engines under one boiler.

The Challengers were designed for fast freight service, but occasionally pulled passenger trains. No. 3985 originally burned coal and pulled a tender with a 32-ton capacity. In 1990, it was converted to use No. 5 oil.

Heading to St. Paul, No. 3985 will operate over rail lines across Wyoming and Nebraska that were built as part of the Transcontinental Route as early as 1866, lines across Iowa that were built as early as 1864 by the Cedar Rapids & Missouri River Railroad, and north to St. Paul over some parts that were built as early as 1870 by the Central Railroad Company of Iowa.