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The EMD MP15, sometimes referenced as MP15DC, is a diesel–electric
Switchers up to the SW1500 had been restricted to AAR type A switcher or Flexicoil lightweight trucks, both with a wheelbase. In 1973 60 special order Mexico-only SW1504s were built on a slightly longer frame, allowing EMD's standard Blomberg B trucks, with a wheelbase, to be used. In EMD's eyes (among others) this made the new locomotive a
road switcher locomotive
A road switcher locomotive is a type of railroad locomotive
designed to both haul railcars in mainline service and shunt them in railroad yards. Both type and term are North American in origin, although similar types have been used elsewhere. ...
model produced by General Motors
General Motors Company (GM) is an American Multinational corporation, multinational Automotive industry, automotive manufacturing company headquartered in Detroit, Michigan, United States. The company is most known for owning and manufacturing f ...
' Electro-Motive Division
Electro-Motive Diesel (abbreviated EMD) is a brand of diesel-electric locomotives, locomotive products and diesel engines for the rail industry. Formerly a division of General Motors, EMD has been owned by Progress Rail since 2010.
Electro-Motiv ...
between 1974 and 1980. It was equipped with a V12 12-645E engine sporting a Roots blower
The Roots blower is a positive displacement lobe pump which operates by pumping a fluid with a pair of meshing lobes resembling a set of stretched gears. Fluid is trapped in pockets surrounding the lobes and carried from the intake side to th ...
. The length was either or depending on the build date.
The early MP15 and the SW1500
The EMD SW1500 is a diesel-electric switcher locomotive built by General Motors' Electro-Motive Division from 1966 to 1974. The SW1500 replaced the SW1200 in the EMD product line. Many railroads regularly used SW1500s for road freight service.
...
were similar in appearance and applications. They were fitted with the same engine in a similar appearance. The primary difference is the MP15's standard Blomberg B trucks.
Development
Switchers up to the SW1500 had been restricted to AAR type A switcher or Flexicoil lightweight trucks, both with a wheelbase. In 1973 60 special order Mexico-only SW1504s were built on a slightly longer frame, allowing EMD's standard Blomberg B trucks, with a wheelbase, to be used. In EMD's eyes (among others) this made the new locomotive a road switcher
A road switcher locomotive is a type of railroad locomotive
designed to both haul railroad car, railcars in mainline service and Shunting (rail), shunt them in railroad yards. Both type and term are North American in origin, although similar t ...
rather than a pure switcher, since it was capable of road speeds up to or so. The new model MP15DC designation thus meant Multi-Purpose locomotive, 1500 hp, DC generator. Originally the locomotive was simply designated the MP15; the arrival of the alternator/rectifier MP15AC in 1975 changed the name.
With the success of the MP15, there was a demand for a model with an advanced AC drive system. The MP15AC replaced the MP15DC's DC generator with an alternator
An alternator (or synchronous generator) is an electrical generator that converts mechanical energy to electrical energy in the form of alternating current. For reasons of cost and simplicity, most alternators use a rotating magnetic field wit ...
producing AC power
In an electric circuit, instantaneous power is the time rate of flow of energy past a given point of the circuit. In alternating current circuits, energy storage elements such as inductors and capacitors may result in periodic reversals of the d ...
which is converted to DC for the traction motors with a silicon rectifier
A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction.
The process is known as ''rectification'', since it "straightens" t ...
. The MP15AC is longer than an MP15DC, the extra space being needed for the rectifier equipment. The alternator-rectifier combination is more reliable than a generator, and this equipment became the standard for new diesel-electric locomotive designs.
The MP15AC is easily distinguished from the DC models. Instead of the front-mounted radiator intake and belt-driven fan used on all previous EMD switchers, these have intakes on the lower forward nose sides and electric fans. Side intakes allowed the unit to take in cooler air, and the electric fans improved a serious reliability issue found in its earlier DC sisters.
Engine
The MP15 used a 12-cylinder version of the 645E series engine developing 1,500 hp at 904±4 rpm. Introduced in the SW1500, this was a 2-stroke, 45-degree V type, with a 9 1⁄16-inch bore by 10-inchstroke
Stroke is a medical condition in which poor cerebral circulation, blood flow to a part of the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemor ...
, giving 645 cubic inches displacement per cylinder. The 645 series, introduced in 1966, was EMD's standard engine through the 1980s.
Original buyers
See also
*List of GM-EMD locomotives
The following is a list of locomotives produced by the Electro-Motive Corporation (EMC), and its successors General Motors Electro-Motive Division (GM-EMD) and Electro-Motive Diesel (EMD).
Streamlined power cars and early experimental locomotive ...
* EMD_MP15AC
The EMD MP15AC is a diesel road switcher locomotive built by General Motors' Electro-Motive Division between August 1975 and August 1984. A variant of the EMD MP15DC with an AC/DC transmission, 246 examples were built, including 25 for export to ...
Notes
References
* * * * {{Diesel_Switchers B-B locomotives MP15DC Diesel–electric locomotives of the United States Standard-gauge locomotives of the United States Standard-gauge locomotives of Canada Shunting locomotives Chicago and North Western Railway locomotives Philadelphia and Reading Railroad locomotives Southern Pacific Railroad locomotives Diesel locomotives of Southern Railway (U.S.) St. Louis–San Francisco Railway locomotives