The EMD MP15, sometimes referenced as MP15DC, is a

switcher A switcher, shunter, yard pilot, switch engine, yard goat, or shifter is a small railroad locomotive used for manoeuvring railroad cars inside a rail yard in a process known as ''switching'' (US) or ''shunting'' (UK). Switchers are not inten ...

-type

diesel locomotive A diesel locomotive is a type of railway locomotive in which the prime mover 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 ...

model produced by

General Motors The General Motors Company (GM) is an American Multinational corporation, multinational Automotive industry, automotive manufacturing company headquartered in Detroit, Michigan, United States. It is the largest automaker in the United States and ...

Electro-Motive Division Progress Rail Locomotives, doing business as Electro-Motive Diesel (EMD), is an American manufacturer of diesel-electric locomotives, locomotive products and diesel engines for the rail industry. The company is owned by Caterpillar through its sub ...

between 1974-1980. It was equipped with an engine sporting a roots blower. The length was either or depending on the build date. The early MP15 and the SW1500 were similar in appearance and applications. They were fitted with the same engine (a V12 EMD 12-645E) 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 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. A road ...

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 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 with a stationary armature.Gor ...

producing AC power 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 reverse operation (converting DC to AC) is performed by an inve ...

. 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 900 rpm. Introduced in the SW1500, this was a 2-stroke, 45-degree V type, with a 9-inch bore by 10-inch

stroke A stroke is a disease, medical condition in which poor cerebral circulation, blood flow to the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemorr ...

, giving 645 cubic inches displacement per cylinder. The 645 series, introduced in 1966, was EMD's standard engine through the 1980s.

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

Development

Engine

See also

Notes

References