4000-Series Big Boy Locomotive History and Locations
Courtesy The Forney Museum of Transportation at 4303 Brighton Blvd., Denver,
Courtesy Wikipedia, the free encyclopedia.
Edited by David Barth 23 June 2012.
Twelve 4000-class 4-8-8-4 engines were built for the Union Pacific by the American Locomotive Company in Schenectady,
New York. The first Big Boy built was number 4000. It arrived in Council Bluffs, Iowa in route to Utah, on September 5,
The original order of fifteen engines, numbered 4000 through 4015, made in 1941, was increased by an order of five more,
numbered 4015 through 4019, in the same year.
These twenty engines were assigned to the Ogden-Green River district to operate on the eastbound Wasatch
mountains, pulling heavy loads from Cheyenne, Wyoming to Ogden, Utah. These engines were needed because the only other
way to pull the loads was to use multiple locomotives.
The final order of five engines, numbered 4020 to 4024, were built in 1944.
|Eight of the 25 Union Pacific Big Boys Still Exist|
|4018||Museum of the American Railroad||Dallas||Texas|
Big Boys were 132 feet in length from the front of the pilot (cowcatcher), to the end of the tender. They weighed
approximately 1.2 million pounds (600 tons). The tender carried 25,000 gallons of water and 26,000 tons of
Coal is fed into the engine by a stoker screw that moves coal from the bottom of the tender, through a tube beneath
the cab, into the firebox. Air jets, operated by the fireman, distribute the coal inside the firebox.
The numbers on the side of the cab below the number, 40xx, are as follows:
- 4-8-8-4: Wheel configuration.
- 68: Diameter of the driving wheels, in inches.
- 23 3/4: Diameter of the pistons, in inches.
- 32: The distance that the pistons travel, in inches.
- 540: The weight, in thousands of pounds, on each of the driving wheels.
- MB: The type of stoker.
The 4-8-8-4 designation of these engines indicates that they have four small pilot wheels in front, eight drive wheels,
eight more drive wheels, and four small wheels beneath the cab. Because the great length of the engine, it was
articulated between the first and second set of eight drivers to enable the engine to negotiate curves in the track.
Even though the locomotives were articulated, some trackage had curves that were too sharp for these engines, and over
the route from Cheyenne to Ogden, these curves had to be straightened or somehow, eliminated. In addition, bridges had
to be checked to make sure they would support these heavy monsters.
Locomotives were not rated in horsepower but in tractive effort derived by using a mathematical formula. However, in
1943 pulling power was calculated differently by using a dynamometer to determine brake horsepower. The Big Boys
developed almost 7,000 horsepower that gave it a top speed of 79 mph, but most freight was pulled at 35 to 45 mph.
During WWII, these trains carried freight, coal, and troops.
Big Boys were built to pull trains over the Continental Divide between Cheyenne, Wyoming and Ogden, Utah. Occasionally,
Big Boys were seen in Denver and rarely in Nebraska, as far east as Kearney, especially during the great blizzard of
Engine 4005, on display at the Forney Museum of Transportation in Denver, Colorado, was retrofitted to burn oil, used
from 1946 to 1948 when a coal strike became a possibility. The engine was converted back to coal because oil was
distributed through a single nozzle in the huge firebox and insufficient heat could be produced in this way.
All Big Boy engines were in use until the fall of 1957. A few briefly pulled freight in July 1959. All Big Boys were
retired from service in 1961 and 1962. 4005 had run approximately one million miles before its retirement. It was the
last Big Boy to roll down Sherman Hill from Green River to Cheyenne, Wyoming where it was given a cosmetic makeover by
the Union Pacific Railroad before being donated to the Forney Museum in June 1970.
Restoration of a Big Boy back to running condition was estimated to be one to three million dollars in 1998. Other
considerations, besides the cost of refurbishing the engine, included allowable track weight restrictions, bridge weight
limits, switches, shop tracks, maintenance costs, etc. There is a rumor that the Union Pacific would not be interested in
running locomotives of this great weight on its trackage.
Big Boy number 4023 was considered to be the most eligible engine to be brought back to operating condition, but that
project was never undertaken. In 1974 it was moved to Omaha. In 2005 it was moved again, this time to the John C.
Kenefick Park located on a steep hill in the Lauritzen Gardens overlooking highway Interstate 80.
The smaller Challenger locomotive, 3900 Class, of which there is only one remaining, is sometimes mistaken for a Big Boy.
These engines pulled loads east of Cheyenne through North Platte, Nebraska and into Council Bluffs.
From Wikipedia, the free encyclopedia:
Big Boy was the name of the Union Pacific Railroad's 4000-class 4-8-8-4 articulated steam locomotives, built between 1941
and 1944 by American Locomotive Company (Alco). The 25 Big Boys were the only locomotives to have the 4-8-8-4 wheel
arrangement, which combined two sets of eight driving wheels with a four-wheel leading truck for stability entering
curves and a four-wheel trailing truck to support the large firebox.
Union Pacific Railroad (UP) introduced the Challenger-type (4-6-6-4) locomotives in 1936 on its main line across Wyoming.
For most of the way, the maximum grade is 0.82% in either direction, but the climb eastward from Ogden, Utah, into the
Wasatch Range (Wahsatch, on the railroad) reached 1.14%. Hauling a 3,600-short ton (3,300 t) freight train demanded
doubleheading and helper operations, and adding and removing the helper engines from a train slowed
The answer was to design a new locomotive, but for such locomotives to be worthwhile they had to be faster and more
powerful than slow mountain luggers like the earlier compound 2-8-8-0s that UP tried after World War I. To avoid
locomotive changes, the new class would need to pull long trains at sustained speed-60 miles per hour (100 km/h)-once
past the mountain grades.
Led by Otto Jabelmann, the UP's design team worked with Alco to re-examine the Challengers, which had been designed
by A.H. Fetters. They found that the goals could be achieved by making several changes to the Challenger design,
including enlarging the firebox to about 235 by 96 inches (6.0 x 2.4 m) (about 155 sq ft/14.4 m2), lengthening the
boiler, adding four driving wheels and reducing the size of the driving wheels from 69 to 68 in
(1.753 to 1.727 m).
The Big Boys are articulated, like the Mallet locomotive design. They were designed for stability at 60 miles per hour
(100 km/h). They were built with a heavy margin of reliability and safety, as they normally operated well below that
speed in freight service. Peak horsepower was reached at about 35 mph (56 km/h); optimal tractive effort, at about
10 mph (16 km/h).
Twenty-five Big Boys were built, in two groups of ten and one of five. All burned coal, and had large grates to burn
the low-quality Wyoming coal from mines owned by the railroad.
As an experiment, Locomotive 4005 was converted to burn oil, but unlike a similar effort with the Challenger types,
this was not successful, and the locomotive was soon changed back to coal. The cited reason for this failure was the use
of a single burner, which created unsatisfactory and uneven heating in the Big Boy's large firebox. It is unknown why
multiple burners were not employed, though with dieselization in full swing after 1945 the company probably lost
interest in further development of steam.
Postwar increases in the price of both coal and labor and the efficiency of diesel-electric motive power foretold a
limited life for the Big Boys, but they were among the last steam locomotives taken out of service. Towards the end of
the 4000s' career (in the late 1950s) it was found that they could still pull more than their rated tonnage of
3,600 tons (3,300 t). Their ratings were increased several times until they regularly pulled 4,450 short tons
(4,040 t) up the Wasatch grade, unassisted.
The last revenue train hauled by a Big Boy ended its run early in the morning on July 21, 1959. Most were stored
operational until 1961, and four remained in operational condition at Green River, Wyoming until 1962. Their duties were
assumed by diesels and turbines.
The Big Boy is well-represented among preserved steam locomotives in the United States. All except 4005 and 4017 are
in the open without protection from the elements.
- The dry air of Southern California has helped 4014 to remain well preserved, assisted by care of the local
chapter of the Railway and Locomotive Historical Society.
- The Steamtown example is also said to be in good condition, though the harsher weather of the northeast has
taken its toll.
- The Forney Transportation Museum in Denver moved 4005 to a renovated building in January 2001.
- Thanks to considerable fundraising and volunteer efforts, 4017 now resides with other pieces of railroad
equipment in a climate-controlled shed at the museum in Green Bay.
- Number 4023 is the only known Big Boy to move by highway since preservation, to the new Kenefick
Park in Omaha.
- Number 4018 is planned to be moved to a new location north of Dallas in Frisco, Texas.
There are no operable Big Boys and no plans to return any to running condition.
|Big Boy Locomotive at the Forney Museum of Transportation. Photo taken by David Barth in
|Big Boy Locomotive 4014 in Pomona, California. |
|Big Boy Locomotive 4023 in Omaha, Nebraska. |
|Big Boy Locomotive 4012 at Steamtown National Historic Site in Scranton, Pennsylvania. |
|Backhead of Big Boy Locomotive 4017 at the National Railroad Museum in Green Bay, Wisconsin. |