DDA40X Union Pacific 6922 In North Platte, Nebraska

This DDA40X is on display at a park in North Platte, Nebraska. The EMD DDA40X was a 6,600 hp (4.9 MW) 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 3,300 hp (2.5 MW)), and although recent locomotive designs such as the AC6000CW and SD90MAC have come close, especially one type of locomotive designed in China, the DF8C, developing 6500HP, the DDA40X remains the most powerful single-unit diesel locomotive type ever built. It is also the longest single-unit diesel locomotive ever built. In 1969 Union Pacific began retiring their gas turbine-electric locomotives, and a more fuel-efficient replacement was needed. Union Pacific had previously ordered EMD DD35s and DD35As 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 (30 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 units. 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.[1]
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.

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[BrunoMTHtrain]

Thank you for the description and history of DDA40X. The view inside the cab is very interesting. The tender seen in the video, is that of a steam locomotive?

[tchnofile]

@BrunoMTHtrain the black locomotive next to it is a 4-6-6-4 steam locomotive the UP 3977, one of the largest in the world.

[tchnofile]

@BrunoMTHtrain the black locomotive next to it is a 4-6-6-4 steam locomotive the UP 3977, one of the largest in the world.

[tchnofile]

@BrunoMTHtrain the black locomotive next to it is a 4-6-6-4 steam locomotive the UP 3977, one of the largest in the world.

[tchnofile]

@BrunoMTHtrain the black locomotive next to it is a 4-6-6-4 steam locomotive the UP 3977, one of the largest in the world.

[jointlinerailfan]

awsome vid. hope I can visit Kody Park some day

[tchnofile]

@jointlinerailfan yeah they got some pretty cool stuff there

[geomodelrailroader]

I have a model of it in my room