EMD DDA40X
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 UP 6915, preserved by the Southern California chapter of the Railway and Locomotive Historical Society at the Los Angeles County Fairplex in Pomona, California. |
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| Power type | Diesel-electric |
|---|---|
| Builder | General Motors Electro-Motive Division (EMD) |
| Build date | June 1969 – September 1971 |
| Total production | 47 |
| AAR wheel arr. | D-D |
| Gauge | 4 ft 8½ in (1,435 mm) |
| Wheelbase | Between truck centers: 65 ft (19.81 m) Truck wheelbase: 17 ft 1.5 in (5.22 m) |
| Length | 98 ft 5 in (30 m) |
| Width | 10 ft 4 in (3.15 m) |
| Height | cab roof: 14 ft 11.375 in (4.56 m) overall: 16 ft 4 in (4.98 m) |
| Locomotive weight | 545,500 lb (247,400 kg) |
| Fuel capacity | 8,230 US gallons (31,154 L) |
| Prime mover | 2 × EMD 645E3A |
| Aspiration | turbocharged |
| Cylinders | V16 |
| Power output | 6600 hp (4,900 kW) |
| Safety systems | Leslie Supertyfon model S5TRRO or S3LR horns |
| Career | Union Pacific |
| Nicknames | "Centennial" |
| Delivered | 6900-6924: June–December 1969 6925-6946: June–September 1971 |
| Disposition | 1 in service, 45 withdrawn, (12 preserved, 34 broken up) |
The EMD DDA40X was a 6,600 hp (4.9 MW) D-D diesel locomotive built by General Motors' Electro-Motive Division of La Grange, Illinois, for the Union Pacific Railroad. 47 locomotives were built between June 1969 and September 1971; they were numbered UP #6900–6946.
The first locomotive, #6900, was delivered in time to participate in the celebrations of the 100th anniversary of the completion of the transcontinental railroad by driving a golden spike at Promontory Summit, Utah. The class was therefore named Centennial by the Union Pacific.
The DDA40X is the longest diesel locomotive design ever built, at 98 ft 5 in (30 m). The locomotive frame length required exceeded the abilities of EMD's plant, so the frames were fabricated by an outside contractor, the John Mohr Company of Chicago. Even today, it is the most powerful diesel locomotive type ever built, although it achieves this by using two diesel prime movers.
The 'X' in the designation stood for Experimental: the DDA40X locomotives were the testbeds for much technology that would go into future EMD products. They pioneered the modular electronic control systems later used on EMD's Dash-2 line of locomotives. For the first time, the locomotive was 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 units. This design closely resembled the Canadian comfort cab used on nearly all hood unit diesels today, but predated it by two decades.
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. These tests were inconclusive, however.
The DDA40X is featured in the third sequel of the successful computer game series Railroad Tycoon under the name "DD40AX".
[edit] Original buyers
| Owner | Quantity |
|---|---|
| Union Pacific Railroad | 47 |
[edit] Surviving examples
- 6900 - Kenefick Park, Omaha, Nebraska
- 6901 - Pocatello, Idaho
- 6911 - Mexico Institute of Technology, Mexico City
- 6913 - Museum of the American Railroad, Dallas, Texas
- 6915 - Southern California Chapter, Railway and Locomotive Historical Society, Fairplex, Pomona, California
- 6916 - Ogden, Utah
- 6922 - North Platte, Nebraska
- 6925 - Stored at Chamberlain, South Dakota, on Dakota Southern Railroad
- 6930 - Illinois Railway Museum, Union, Illinois. Used as a control cab only, motors are currently non-operational.
- 6936 - Still in service with Union Pacific Heritage Fleet
- 6938 - North Little Rock, Arkansas
- 6944 - Museum of Transportation, St. Louis, Missouri
- 6946 - Western Pacific Railroad Museum, Portola, California. The last DDA40X built. This locomotive is fairly complete and on static display.
[edit] References
- Strack, Don. Union Pacific's DDA40X Centennial Locomotives. Retrieved on May 11, 2005.
- Hayden, Bob (Ed.) (1980). Model Railroader Cyclopedia-Volume 2: Diesel Locomotives. Kalmbach Books. ISBN 0-89024-547-9.
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