EMD DDA40X

EMD DDA40X
UP 6922 at Cody Park; North Platte, Nebraska.
Power type	Diesel-electric
Builder	General Motors Electro-Motive Division (EMD)
Build date	April 1969 – September 1971
Total produced	47
AAR wheel arr.	D-D
Gauge	4 ft 8 1⁄2 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	521,980lb (261 tons)
Fuel capacity	8,230 US gallons (31,154 L)
Prime mover	2 × EMD 645E3A
Aspiration	turbocharged
Cylinders	V16
Power output	6600 traction hp (4,900 kW)
Safety systems	Leslie Supertyfon model S5TRRO or S3LR horns, US&S Type 'EL' Cab Signals (#6936 equipped with US&S MicroCab ATC & CCS)
Career	Union Pacific
Number	6900 – 6946
Nicknames	"Centennial"
Delivered	6900-6924 April – December 1969 6925-6946 June 1970 – September 1971
Disposition	1 in service, 46 withdrawn, (12 preserved, 34 scrapped)

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, 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.^{[citation needed]}

Description

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.

Original buyers

Owner	Quantity
Union Pacific Railroad	47

Surviving examples

The engineer's control stand.

• 6900 - Kenefick Park, Omaha, Nebraska
• 6901 - Ross Park, 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 - Utah State Railroad Museum, Ogden, Utah
• 6922 - Cody Park, North Platte, Nebraska
• 6925 - Stored at Chamberlain, South Dakota, on Dakota Southern Railway
• 6930 - Illinois Railway Museum, Union, Illinois. Used as a control cab only, engines and motors are currently non-operational.
• 6936 - Still in service with Union Pacific Heritage Fleet
• 6938 - North Little Rock, Arkansas (Sits in front of Jenks Locomotive Facility)
• 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.

References

1. ^ CN Locomotive Cab Layout GR-20c, Commission of Inquiry Hinton Train Collision, December 1986

• Union Pacific Railroad Locomotive Department (1979). Locomotive Diagram Book. Union Pacific Railroad Company.
• Union Pacific Railroad Locomotive Department (1994). Locomotive Diagram Book. Union Pacific Railroad Company.
• 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. 
• WikiAnswers - Traction horsepower

External links

• Union Pacific DDA40X Centennial 6922 Oct 20 1984