EMD DDA40X
Encyclopedia
The EMD DDA40X was a 6600 hp D-D diesel-electric locomotive
built by the General Motors EMD division of La Grange, Illinois
for the Union Pacific Railroad
. Nicknamed "Centennial" and "Big Jack", it uses two diesel engines (each providing 3300 hp), and although recent locomotive designs such as the AC6000CW
, SD90MAC
and the China Railway DF8C have come close, the DDA40X remains the most powerful single-unit diesel locomotive type ever built. It is also the longest single-unit diesel locomotive ever built.
, and a more fuel-efficient replacement was needed. Union Pacific had previously ordered EMD DD35
s and DD35A
s to replace the turbines, and the DDA40X was a further development of the concept. Forty seven locomotives of this type were built between June 1969 and September 1971, except the first one delivered in April in time to participate in the celebrations of the centennial anniversary of the completion of the Transcontinental Railroad
driving the "Gold Spike Limited" and arriving in Salt Lake City, Utah
, on the morning of May 10, 1969. The units were numbered from 6900 to 6946, with 6936
still in service.
The DDA40X is 98 ft (29.9 m) long. The frames were fabricated by an outside contractor, the John Mohr Company of Chicago, since the locomotive frame length exceeded the abilities of EMD's plant. The concept of using more than one prime mover in a single locomotive was not new. The EMD E-series was one of the more popular dual-engine locomotives, and Baldwin had produced (but not sold) a locomotive with four diesel engines.
The 'X' in the designation stood for Experimental, as the DDA40X locomotives were used as the testbeds for technology that would go into future EMD products. The modular electronic control systems later used on EMD's Dash-2 line of locomotives were first used on the DDA40X. The locomotive was the first to be able to load-test itself using its dynamic braking
resistors as an electrical load so that external equipment was not required. The DDA40X used the wide-nosed cab
from the FP45
cowl unit
s. This design was superficially similar to the Canadian comfort cab
introduced by Canadian National soon afterwards in 1973, but it lacked the structural reinforcements introduced in the CN design that were carried over to future wide-nosed cabs.
As the DDA40X program was deemed a testbed, a number of experiments were conducted during the service life of these locomotives. One such test included fitting a few of the units with air raid sirens in order to warn trackside personnel when away from grade crossings, but the results were inconclusive.
Diesel locomotive
A diesel locomotive is a type of railroad locomotive in which the prime mover is a diesel engine, a reciprocating engine operating on the Diesel cycle as invented by Dr. Rudolf Diesel...
built by the General Motors EMD division of La Grange, Illinois
La Grange, Illinois
La Grange, a suburb of Chicago, is a village in Cook County, in the U.S. state of Illinois. The population was 15,608 at the 2000 census.-History:...
for the Union Pacific Railroad
Union Pacific Railroad
The Union Pacific Railroad , headquartered in Omaha, Nebraska, is the largest railroad network in the United States. James R. Young is president, CEO and Chairman....
. Nicknamed "Centennial" and "Big Jack", it uses two diesel engines (each providing 3300 hp), and although recent locomotive designs such as the AC6000CW
GE AC6000CW
The AC6000CW is a diesel electric locomotive that is built by GE Transportation Systems. They are all used by major railroads in the United States, except for 8 units exported to BHP Billiton Iron Ore in Australia...
, SD90MAC
EMD SD90MAC
The EMD SD90MAC is a C-C diesel-electric hood unit locomotive produced by General Motors Electro-Motive Division. It is, with the SD80MAC, one of the largest single-engined locomotives produced by that company, surpassed only by the dual-engined DD series...
and the China Railway DF8C have come close, the DDA40X remains the most powerful single-unit diesel locomotive type ever built. It is also the longest single-unit diesel locomotive ever built.
Description
In 1969 Union Pacific began retiring their gas turbine-electric locomotivesUnion Pacific GTELs
Union Pacific operated the largest fleet of gas turbine-electric locomotives of any railroad in the world. The prototype, UP 50 was the first in a series built by General Electric for Union Pacific's long-haul cargo services. The prototype was introduced in 1948 and was followed by three series...
, and a more fuel-efficient replacement was needed. Union Pacific had previously ordered EMD DD35
EMD DD35
The EMD DD35 was a diesel-electric locomotive of D-D wheel arrangement built by General Motors Electro-Motive Division for the Union Pacific Railroad and Southern Pacific Railroad. In the early 1960s Union Pacific started asking for a 15,000 hp 3-unit locomotive set to replace the turbines...
s and DD35A
EMD DD35A
The EMD DD35A was a 5,000 hp diesel locomotive of D-D wheel arrangement built by General Motors Electro-Motive Division exclusively for the Union Pacific Railroad. They were a cab-equipped variant of the previous, cabless booster EMD DD35...
s to replace the turbines, and the DDA40X was a further development of the concept. Forty seven locomotives of this type were built between June 1969 and September 1971, except the first one delivered in April in time to participate in the celebrations of the centennial anniversary of the completion of the Transcontinental Railroad
Transcontinental railroad
A transcontinental railroad is a contiguous network of railroad trackage that crosses a continental land mass with terminals at different oceans or continental borders. Such networks can be via the tracks of either a single railroad, or over those owned or controlled by multiple railway companies...
driving the "Gold Spike Limited" and arriving in Salt Lake City, Utah
Utah
Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...
, on the morning of May 10, 1969. The units were numbered from 6900 to 6946, with 6936
Union Pacific 6936
Union Pacific 6936 is an EMD DDA40X locomotive owned by Union Pacific Railroad . It is the sole example of the "Centennial" type that is still in operation, and thus is the largest operational diesel-electric locomotive in the world...
still in service.
The DDA40X is 98 ft (29.9 m) long. The frames were fabricated by an outside contractor, the John Mohr Company of Chicago, since the locomotive frame length exceeded the abilities of EMD's plant. The concept of using more than one prime mover in a single locomotive was not new. The EMD E-series was one of the more popular dual-engine locomotives, and Baldwin had produced (but not sold) a locomotive with four diesel engines.
The 'X' in the designation stood for Experimental, as the DDA40X locomotives were used as the testbeds for technology that would go into future EMD products. The modular electronic control systems later used on EMD's Dash-2 line of locomotives were first used on the DDA40X. The locomotive was the first to be able to load-test itself using its dynamic braking
Dynamic braking
Dynamic braking is the use of the electric traction motors of a railroad vehicle as generators when slowing the Locomotive. It is termed rheostatic if the generated electrical power is dissipated as heat in brake grid resistors, and regenerative if the power is returned to the supply line...
resistors as an electrical load so that external equipment was not required. The DDA40X used the wide-nosed cab
Cab (locomotive)
The cab, crew compartment or driver's compartment of a locomotive is the part of the locomotive housing the train driver or engineer, the fireman or driver's assistant , and the controls necessary for the locomotive's operation....
from the FP45
EMD FP45
The EMD FP45 is a cowl unit type of C-C diesel locomotive produced in the United States by General Motors Electro-Motive Division. It was produced beginning in 1967 at the request of the Atchison, Topeka and Santa Fe Railway, which did not want its prestigious Super Chief and other passenger...
cowl unit
Cowl unit
A cowl unit is a body style of diesel locomotive. The terminology is a North American one, though similar locomotives exist elsewhere. A cowl unit is one with full-width enclosing bodywork, similar to the cab unit style of earlier locomotives, but unlike the cab unit style, the bodywork is merely...
s. This design was superficially similar to the Canadian comfort cab
Canadian comfort cab
The Canadian comfort cab or wide cab is a broad-nosed cab design found on modern diesel locomotives. It occupies the entire width of the locomotive, and typically has an access door on the front of the nose...
introduced by Canadian National soon afterwards in 1973, but it lacked the structural reinforcements introduced in the CN design that were carried over to future wide-nosed cabs.
As the DDA40X program was deemed a testbed, a number of experiments were conducted during the service life of these locomotives. One such test included fitting a few of the units with air raid sirens in order to warn trackside personnel when away from grade crossings, but the results were inconclusive.
Original buyers
| Owner | Quantity |
|---|---|
| Union Pacific Railroad | 47 |
Surviving examples
- 6900 - Kenefick ParkKenefick ParkKenefick Park is located at 100 Bancroft Street in South Omaha, Nebraska. Located next to the Lauritzen Gardens, Omaha's botanical gardens, the park features "two of the greatest locomotives ever to power Union Pacific Railroad."-About:...
, Omaha, NebraskaOmaha, NebraskaOmaha is the largest city in the state of Nebraska, United States, and is the county seat of Douglas County. It is located in the Midwestern United States on the Missouri River, about 20 miles north of the mouth of the Platte River... - 6901 - Ross Park, Pocatello, IdahoPocatello, IdahoPocatello is the county seat and largest city of Bannock County, with a small portion on the Fort Hall Indian Reservation in neighboring Power County, in the southeastern part of the U.S. state of Idaho. It is the principal city of the Pocatello metropolitan area, which encompasses all of Bannock...
- 6911 - Mexico Institute of Technology, Mexico CityMexico CityMexico City is the Federal District , capital of Mexico and seat of the federal powers of the Mexican Union. It is a federal entity within Mexico which is not part of any one of the 31 Mexican states but belongs to the federation as a whole...
- 6913 - Museum of the American RailroadMuseum of the American RailroadThe Museum of the American Railroad, formerly known as the Age of Steam Railroad Museum, is located at 1105 Washington Street in Fair Park, Dallas, Texas. The museum has a large collection of steam, diesel and passenger railroad equipment...
, Dallas, TexasDallas, TexasDallas is the third-largest city in Texas and the ninth-largest in the United States. The Dallas-Fort Worth Metroplex is the largest metropolitan area in the South and fourth-largest metropolitan area in the United States... - 6915 - Southern California Chapter, Railway and Locomotive Historical Society, FairplexFairplexFairplex, formerly known as the Los Angeles County Fairgrounds, has been since 1922 the home of the L.A. County Fair. It is located in the city of Pomona, California. The L.A...
, Pomona, CaliforniaPomona, California-2010:The 2010 United States Census reported that Pomona had a population of 149,058, a slight decline from the 2000 census population. The population density was 6,491.2 people per square mile... - 6916UP 6916Union Pacific 6916 is a DDA40X diesel locomotive built for the Union Pacific Railroad. It now resides in the Eccles Rail Center at the Utah State Railroad Museum in Ogden, Utah.-History:...
- Utah State Railroad Museum, Ogden, UtahOgden, UtahOgden is a city in Weber County, Utah, United States. Ogden serves as the county seat of Weber County. The population was 82,825 according to the 2010 Census. The city served as a major railway hub through much of its history, and still handles a great deal of freight rail traffic which makes it a... - 6922Union Pacific 6922Union Pacific 6922 is an EMD DDA40X locomotive previously owned by Union Pacific Railroad . The railroad donated the locomotive to North Platte, Nebraska in October 1985 and it was put on display in Cody Park, next to Challenger #3977.- External links :...
- Cody Park, North Platte, NebraskaNorth Platte, NebraskaNorth Platte is a city in and the county seat of Lincoln County, Nebraska, United States. It is located in the southwestern part of the state, along Interstate 80, at the confluence of the North and South Platte Rivers forming the Platte River... - 6925 - Stored at Chamberlain, South DakotaChamberlain, South DakotaChamberlain is a city in Brule County, South Dakota, United States. The population was 2,387 at the 2010 census. It is the county seat of Brule County. Chamberlain is home to the Akta Lakota Museum and Cultural Center, which profiles the lives of nomadic Plains Indians...
, on Dakota Southern RailwayDakota Southern RailwayThe Dakota Southern Railway is a railway that runs between Kadoka, South Dakota and Mitchell, South Dakota. It connects with the BNSF Railway in Mitchell.-History:... - 6930 - Illinois Railway MuseumIllinois Railway MuseumThe Illinois Railway Museum is the largest railroad museum in the United States and is located in Union, Illinois, northwest of Chicago...
, Union, IllinoisUnion, IllinoisUnion is a village in McHenry County, Illinois, United States. The population was 580 at the 2010 census, up from 576 at the 2000 census.-Geography:Union is located at ....
. Used as a control cab only, engines and motors are currently non-operational. - 6936Union Pacific 6936Union Pacific 6936 is an EMD DDA40X locomotive owned by Union Pacific Railroad . It is the sole example of the "Centennial" type that is still in operation, and thus is the largest operational diesel-electric locomotive in the world...
- Still in service with Union Pacific Heritage Fleet - 6938 - North Little Rock, ArkansasNorth Little Rock, Arkansasthe city was 62.55% White, 33.98% Black or African American, 0.41% Native American, 0.59% Asian, 0.03% Pacific Islander, 1.18% from other races, and 1.26% from two or more races...
(Sits in front of Jenks Locomotive Facility) - 6944 - Museum of TransportationMuseum of TransportationThe Museum of Transportation of the St. Louis County, Missouri, United States Parks Department is a museum located in the Greater St. Louis area. It was first founded in 1944 by a group of individuals dedicated to preserving the past and has a wide variety of vehicles from American history...
, St. Louis, MissouriSt. Louis, MissouriSt. Louis is an independent city on the eastern border of Missouri, United States. With a population of 319,294, it was the 58th-largest U.S. city at the 2010 U.S. Census. The Greater St... - 6946 - Western Pacific Railroad MuseumWestern Pacific Railroad MuseumThe Western Pacific Railroad Museum in Portola, California, formerly known as the Portola Railroad Museum before , is a heritage railroad that preserves and operates historic American railroad equipment. The museum's mission is to preserve the history of the Western Pacific Railroad and is...
, Portola, CaliforniaPortola, CaliforniaPortola is the only incorporated city in Plumas County, California, United States. The population was 2,104 at the 2010 census, down from 2,227 at the 2000 census...
. The last DDA40X built. This locomotive is fairly complete and on static display.