EMD DDA40X

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EMD DDA40X
UnionPacific6922.jpg
UP DDA40X #6922 at Cody Park; North Platte, Nebraska.
Specifications
Power typeDiesel-electric
BuilderGeneral Motors Electro-Motive Division (EMD)
Build dateApril 1969 – September 1971
Total produced47
AAR wheel arr.D-D
Gauge4 ft 8 12 in (1,435 mm)
WheelbaseBetween truck centers: 65 ft (19.81 m)
Truck wheelbase:
17 ft 1 12 in (5.22 m)
Length98 ft 5 in (30.00 m)
Width10 ft 4 in (3.15 m))
Heightcab roof: 14 ft 11 38 in (4.56 m)
overall: 16 ft 4 in (4.98 m)
Locomotive weight521,980 lb (236,770 kg)
or 260.99 short tons (233.03 long tons; 236.77 t)
Fuel capacity8,230 US gal (31,200 l; 6,850 imp gal)
Prime mover2 × EMD 645E3A
Aspirationturbocharged
CylindersV16
Power output6,600 hp (4,920 kW)
Safety systemsLeslie 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
Number6900 – 6946
Nicknames"Centennial", "Big Jack"
Delivered6900-6924 April – December 1969
6925-6946 June 1970 – September 1971
Disposition1 in service, 46 withdrawn, (13 preserved, 34 scrapped)
 
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EMD DDA40X
UnionPacific6922.jpg
UP DDA40X #6922 at Cody Park; North Platte, Nebraska.
Specifications
Power typeDiesel-electric
BuilderGeneral Motors Electro-Motive Division (EMD)
Build dateApril 1969 – September 1971
Total produced47
AAR wheel arr.D-D
Gauge4 ft 8 12 in (1,435 mm)
WheelbaseBetween truck centers: 65 ft (19.81 m)
Truck wheelbase:
17 ft 1 12 in (5.22 m)
Length98 ft 5 in (30.00 m)
Width10 ft 4 in (3.15 m))
Heightcab roof: 14 ft 11 38 in (4.56 m)
overall: 16 ft 4 in (4.98 m)
Locomotive weight521,980 lb (236,770 kg)
or 260.99 short tons (233.03 long tons; 236.77 t)
Fuel capacity8,230 US gal (31,200 l; 6,850 imp gal)
Prime mover2 × EMD 645E3A
Aspirationturbocharged
CylindersV16
Power output6,600 hp (4,920 kW)
Safety systemsLeslie 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
Number6900 – 6946
Nicknames"Centennial", "Big Jack"
Delivered6900-6924 April – December 1969
6925-6946 June 1970 – September 1971
Disposition1 in service, 46 withdrawn, (13 preserved, 34 scrapped)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[edit]

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[edit]

OwnerQuantity
Union Pacific Railroad47

Surviving examples[edit]

The engineer's control stand.

References[edit]

  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/

External links[edit]