"Big Boy"

"Big Boy". ALCo's Mighty 4-8-8-4. "Big Boy” was a lot of rolling steel - a whopping 1,250,000 pounds, or 612.5 tons of it with its tender included. The American Locomotive Company built 25 of these mammoth locomotives for the Union Pacific Railroad between the years 1941 and 1944. They were designed to pull mile-long freight trains through the Wasatch Range from Ogden, Utah, to Wyoming's Green River., For most of this route, the maximum grade is .82%, but a stretch of it reaches a 1.14% grade and required two large locomotives coupled together (double-headers) to pull a 3900-ton train through the range. Big Boys were designed to haul even heavier trains with a single locomotive., The Union Pacific design team working with ALCO came up with the solution: a 4-8-8-4 wheel arrangement., Four leading wheels (trucks) were followed by two separate sets of eight driving wheels and a set of four trailing wheels for stability. With twenty-four wheels in all, the design was the largest, most powerful coal-fired locomotive ever built. A Big Boy could haul a 7900-ton freight train through the Wasatch at over 60 mph., As the era of steam locomotives gave way to diesel in the early 1950s, the Big Boys' days were numbered. Its last commercial run was made on July 21 1959. To this day, the Big Boy built in Schenectady is the largest locomotive that the world has ever known.