EMD DDA40X

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EMD DDA40X

UP DDA40X #6922 at Cody Park; North Platte, Nebraska.
Specifications
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 1⁄2 in (5.22 m)
Length 98 ft 5 in (30.00 m)
Width 10 ft 4 in (3.15 m))
Height cab roof: 14 ft 11 3⁄8 in (4.56 m)
overall: 16 ft 4 in (4.98 m)
Locomotive weight 521,980 lb (236,770 kg)
or 260.99 short tons (233.03 long tons; 236.77 t)
Fuel capacity 8,230 US gal (31,200 l; 6,850 imp gal)
Prime mover 2 × EMD 645E3A
Aspiration turbocharged
Cylinders V16
Power output 6,600 hp (4,920 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
Railroad(s) Union Pacific
Number 6900 – 6946
Nicknames "Centennial", "Big Jack"
Delivered 6900-6924 April – December 1969
6925-6946 June 1970 – September 1971
Disposition 1 in service, 46 withdrawn, (13 preserved, 34 scrapped)

The EMD DDA40X was a 6,600 hp (4.92 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", the DDA40X uses two diesel engines (each providing 3,300 hp (2.46 MW)) and remains the most powerful single-unit diesel locomotive type ever built, although more recent locomotive designs such as the GE AC6000CW, EMD SD90MAC and the China Railway DF8C have come close. It is also the longest single-unit diesel locomotive ever built.[1]

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.[2]

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.

Union Pacific began retiring its DD40Xs in 1984 due to rising maintenance costs, with all retired by the end of 1986.[3] Number 6936 however is still in service with UP, though mostly in excursion service.

Original buyers

Owner Quantity
Union Pacific Railroad 47

Surviving examples

The engineer's control stand.

References

Wikimedia Commons has media related to EMD DDA40X locomotives.
  1. ↑ Utah Rails DDA40X page
  2. ↑ CN Locomotive Cab Layout GR-20c, Commission of Inquiry Hinton Train Collision, December 1986
  3. ↑ http://www.steamlocomotive.com/centennials/
  • 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

6- and 8-axle diesel-electric locomotives built by GM-EMD
Six-axle road power
Eight-axle road power
Giant locomotives of the Union Pacific Railroad
 
American Locomotive Company (ALCO)
Electro-Motive Division, GM (EMD)
General Electric (GE)
 
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