The M-K TE70-4S was a four-axle B-B

diesel-electric locomotive A diesel locomotive is a type of railway locomotive in which the power source is a diesel engine. Several types of diesel locomotives have been developed, differing mainly in the means by which mechanical power is conveyed to the driving whee ...

built by Morrison-Knudsen. The locomotive was a rebuild of the GE U25B with a Sulzer V-12

prime mover Prime mover may refer to: Philosophy *Unmoved mover, a concept in Aristotle's writings Engineering * Prime mover (engine or motor), a machine that converts various other forms of energy (chemical, electrical, fluid pressure/flow, etc.) into ener ...

installed. Morrison-Knudsen rebuilt four for the

Southern Pacific Railroad The Southern Pacific (or Espee from the railroad initials) was an American Railroad classes#Class I, Class I Rail transport, railroad network that existed from 1865 to 1996 and operated largely in the Western United States. The system was oper ...

in 1978. The experiment proved unsuccessful and no additional units were rebuilt.

Design

The

for the M-K TE70-4S was a Sulzer 12ASV 25/30. Normally found in marine or stationary uses, the 12ASV 25/30 had been in production since 1969. The

four-stroke A four-stroke (also four-cycle) engine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either directio ...

turbocharged In an internal combustion engine, a turbocharger (also known as a turbo or a turbosupercharger) is a forced induction device that is powered by the flow of exhaust gases. It uses this energy to compress the intake air, forcing more air into the ...

engine was rated for a maximum of at 1000

RPM Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or r⋅min−1) is a unit of rotational speed (or rotational frequency) for rotating machines. One revolution per minute is equivalent to hertz. Standards ISO 80000-3:2019 def ...

. The locomotives retained the GE GT598 D3A generators and GE 752

traction motor A traction motor is an electric motor used for propulsion of a vehicle, such as locomotives, electric vehicle, electric or hydrogen vehicles, or electric multiple unit trains. Traction (engineering), Traction motors are used in electrically powe ...

s from the U25B. The capability of the prime mover notwithstanding, the locomotive was rated at . The new prime mover required substantial alterations to the cab, carbody, and underframe. The locomotive measured long by wide, and stood high. It weighed .

History

Southern Pacific sent four GE U25Bs ( 7030–7033), then at the end of their service life, to Morrison-Knudsen for rebuilding. Morrison-Knudsen rebuilt the four locomotives in its

Boise, Idaho Boise ( ) is the List of capitals in the United States, capital and List of cities in Idaho, most populous city of the U.S. state of Idaho. As of the 2020 United States census, 2020 census, there were 235,685 people residing in the city. Loca ...

, shops in 1977–1978. The first revenue run occurred beginning March 1, 1978, when the four locomotives handled a

Seattle Seattle ( ) is the most populous city in the U.S. state of Washington and in the Pacific Northwest region of North America. With a population of 780,995 in 2024, it is the 18th-most populous city in the United States. The city is the cou ...

–

Los Angeles Los Angeles, often referred to by its initials L.A., is the List of municipalities in California, most populous city in the U.S. state of California, and the commercial, Financial District, Los Angeles, financial, and Culture of Los Angeles, ...

trailer-on-flatcar (TOFC) train between Portland and Los Angeles. Inauspiciously, one of the four locomotives broke down during the trip. The locomotives carried a unique paint scheme featuring the red-and-orange of the SP's famed "Daylight" passenger trains, albeit in a different style. The color scheme led to the nickname " Popsicle". Due to their consistent unreliability, all four were retired in 1987 after less than ten years; none were preserved.

Notes

References

* * * * * *

External links

Southern Pacific TE70-4S on My Espee Modelers Archive
{{MPI Locomotives TE70-4S B-B locomotives Diesel–electric locomotives of the United States Railway locomotives introduced in 1978 Freight locomotives Standard-gauge locomotives of the United States

Design

History

Notes

References

Further reading

External links