Union Pacific Big Boy - wallpapers: Big Boy was the nickname universally applied to the Union Pacific Railroad's twenty-five 4000 class 4-8-8-4 steam locomotives built between 1941 and 1944 by Alco. They are often proclaimed as the largest steam locomotives ever built, but that title is quite controversial—there were heavier locomotives, and possibly more powerful locomotives. However, without tender, the Big Boy's locomotive body was the longest of all of them and fully loaded with water and fuel the Big Boy was the heaviest of all of them, even though the locomotive without tender was lighter than some. However, the Big Boy is in the running in every category, and it certainly could be said to be the most successful of the giant locomotives. The Big Boys were certainly the only locomotives to have the 4-8-8-4 wheel arrangement in the Whyte notation—in other words, combining two sets of eight driving wheels with both a four-wheel leading truck for stability at speed and a four-wheel trailing truck to support a large firebox. Just examining the locomotive arrangement makes it clear that the Big Boy's forté was power at speed, and that's exactly what they were designed for. The Big Boy locomotives were created by the Union Pacific's need for a locomotive that could pull a 3600 short ton (3300 metric ton) freight train over the long 1.14% grade of the Wasatch. Helpers were needed for this grade at the time, but adding and removing them, crewing them, etc. both slowed down the movement of trains. However, for such a locomotive to be worthwhile, it had to be more than just a slow mountain lugger; to avoid locomotive changes, the new class would have to be able to pull that long train at speed —60 mph (100 km/h)—once past the mountain grades. In fact, the Big Boys were designed to be stable at 80 mph (130 km/h), so they were built with a heavy margin of safety. Few previous articulated locomotives were capable of such speed; UP's earlier Challenger 4-6-6-4s were, however, and in many respects the Big Boy could be regarded as a longer, heavier and more powerful Challenger. Twenty-five of them were built, split into two groups of 20 locomotives and 5 locomotives respectively. All were coal burners, with large grates to burn the Union Pacific's low quality Wyoming coal. One locomotive, #4005, was temporarily converted to oil firing, but unlike the experiences on the smaller Challengers, oil firing was not successful, and the locomotive soon reverted to standard configuration. The often cited reason for the unsuccessful oil-fired test was the use of a single burner which, with the Big Boy's larger firebox, created a very unsatisfactory and uneven heating. Unexplained is the reason multiple burners were not utilized. They did sterling service in the Second World War, especially since they proved so easy to fire that even a novice could do a fair job. Since many men who were unsuited to combat service were instead drafted into railroad service to replace crewmen who joined up, this proved essential. Like all steam locomotives, postwar increases in the price of both coal and labor meant that the writing was on the wall, but even so they were among the last steam locomotives taken out of service. The last service train hauled by a Big Boy was in July 1959, the last run ending early in the morning of July 21st; most were stored operational until 1961, and four remained in operational condition at Green River, Wyoming, until 1962.
