Laying just a stone's throw east of Ogden are Utah's Wasatch Mountains, a beautiful but quite rugged range that plagued the Union Pacific since it first laid rails westward through the region in the late 1860s. As part of the railroad's Overland Route main line the stretch of track between Ogden and Wasatch, which saw grades top out at 1.14% for eastbound movements, was quite busy. In 1936 UP introduced its latest locomotive to tackle the steep grades, its fleet of 4-6-6-4 Challengers designed by A.H. Fetters. However, even these powerful steamers still required either helpers or doubleheading to move a 3,600-ton train over the mountain, which added to transit times by adding and removing the extra locomotive(s). Looking for a single unit to do the job UP went to its Department of Research and Mechanical Standards (DoRMS) led by Otto Jabelmann to come up with a new design that was not only powerful but also faster.
Teaming up with the American Locomotive Company (Alco), Jabelmann and
Fetters discovered that beefing up the current 4-6-6-4 design would
achieve the desired results by increasing the size of the firebox,
lengthening the boiler, adding two additional sets of drivers, and
shortening the driving wheels from 69 to 68 inches. Through these
changes the new 4-8-8-4 design offered tractive efforts exceeding
135,000 pounds and could operate at speeds of 80 mph (although no Big
Boys actually ever reached these speed while in service, it was an added
safety factor built in to the locomotive by its designers to assume a
safe operation of up to 60 mph). According to SteamLocomotive.com the first Union Pacific Big Boy was delivered in Omaha, Nebraska from Alco's Schenectady, New York plant at 6 p.m. on September 5, 1941.
Big Boy Specifications
Builder - American Locomotive Company (Alco)
Fuel - 28 tons
Cyclinders(4) - 23.75" x 32"
Water - 25,000 Gallons
Weight - 1,208,000 Pounds
Diameter of Drivers - 68 Inches
Steam Pressure - 300 PSI
Tractive Effort - 135,375 Pounds
Numbered 4000, Union Pacific would go on to roster two distinct classes of 4-8-8-4s listed simply as Class 1 (4000-4019) and Class 2 (4020-4024) with Alco delivering the final locomotive to the railroad in 1944. Due to nearby mines in Wyoming owned by UP all of the 4-8-8-4s burned coal although as an experiment #4005 was briefly converted to an oil-burner, which proved unsuccessful. The Big Boys went on to not only tackle the grades east of Ogden but also worked the Wyoming Division over fabled Sherman Hill east of Lamarie. Because the diesel was already making its presence known as a main line locomotive when the Big Boy was developed the steamer saw a short lifespan, despite being one of the technologically advanced of its kind ever built.
The last revenue run of a 4-8-8-4 occurred on July 21, 1959 although the railroad continued to store four, serviceable at Green River, Wyoming through September of 1962. In any event, most 4-8-8-4s barely saw 20
years of service before retirement, a very young steam locomotive
when compared to some still operating today that were built near or
over 100 years ago. The Union Pacific Big Boy is often mentioned as the
largest steamer ever built, sometimes even saying that they are the
most powerful. While in some areas that is the case, in others it is
not especially in regards to the overall power it exerted. For example,
Norfolk & Western Y6 and C&O H-8 designs, themselves monsters,
were more powerful and larger than the Big Boy in the areas of tractive
effort, weight, length and horsepower.
In any event, while the “largest” and “most powerful” steam locomotive
will likely always be debated by railfans and historians one thing which
cannot be argued is how fortunate this locomotive was compared to other
large locomotives like it in regards to preservation. No less than eight of these monsters have
been saved and are currently scattered about the country in various
parks. They include numbers; 4004-4006, 4012, 4014, 4017, 4018, and
While perhaps the size of the Big Boy will prohibit even the
preservation-minded Union Pacific from operating one of them over its
system, as it currently does with its originally owned Challenger #3985
and UP #844 (the only steam locomotive in America to never be retired
from active service), it is nevertheless good to see that so many Big
Boys have been preserved for future generations to have a glimpse at
these truly mighty locomotives.
Finally, as incredible as it seems news leaked on December 7, 2012
that Union Pacific was contemplating restoring a Big Boy back into
operating condition for the railroad's 150th celebration in 2019. After a few months of working out the details the locomotive was secured by the railroad during July of 2013. During early 2014 the massive 4-8-8-4 was moved from its long-time resting place at the Los Angeles County Fairgrounds, a spectacle widely documented by numerous media outlets. Today, the Big Boy is safely tucked away inside the roundhouse at Cheyenne, Wyoming where it will undergo a multi-year restoration before returning to steam at an unspecified date in the future. Naturally, such an event is widely anticipated not only in the railfan community but also the general public as well!