The MPI MP8AC-3 is a light-weight diesel locomotive built by the

MotivePower MotivePower, Inc. (MPI) is an American manufacturer of diesel-electric locomotives. The company is a wholly-owned subsidiary of Wabtec, and traces its history back to the MK Rail division of Morrison-Knudsen. History Morrison-Knudsen establ ...

division of

Wabtec Wabtec Corporation (derived from Westinghouse Air Brake Technologies Corporation) is an American company formed by the merger of the Westinghouse Air Brake Company (WABCO) and MotivePower Industries Corporation in 1999. It is headquartered ...

. It was designed from scratch as a

work train A work train or departmental train (engineering train in the UK) is one or more rail cars intended for internal non-revenue use by the railroad's operator. Work trains serve functions such as track maintenance, maintenance of way, revenue coll ...

engine for the New York City Subway system, where it is designated the R156.

Description

The R156 is designed to navigate the clearances and tight turns of the NYC subway, with weight constrained to , so it can operate on elevated portions of the system. It joins a fleet of 62 diesel-electric work locomotives on the system.

Third rail A third rail, also known as a live rail, electric rail or conductor rail, is a method of providing electric power to a railway locomotive or train, through a semi-continuous rigid conductor placed alongside or between the rails of a railway ...

power is not used because the third rail is normally turned off at work sites for safety reasons. Instead, the R156 is powered by a 6-cylinder, 800 horsepower

Cummins Cummins Inc. is an American multinational corporation that designs, manufactures, and distributes engines, filtration, and power generation products. Cummins also services engines and related equipment, including fuel systems, controls, air ...

QSK 23 diesel engine. A separate, smaller John Deere Diesel drives a generator to provide

auxiliary power Auxiliary power is electric power that is provided by an alternate source and that serves as backup for the primary power source at the station main bus or prescribed sub-bus. An offline unit provides electrical isolation between the primary pow ...

and to heat the main engine and keep batteries charged when the main engine is not running. Trucks are supplied by Kawasaki, which provides the same wheel and traction sets for the R160 subway cars. The traction motors are Siemens' SITRAC AC motors (the same ones on R160Bs 8843–9102). The R156 locomotives have provisions for the future installation of

communications-based train control Communications-based train control (CBTC) is a railway signaling system that uses telecommunications between the train and track equipment for traffic management and infrastructure control. CBTC allows a train's position to be known more accurat ...

(CBTC) equipment, which were expected to be installed by June 2017. The MTA ordered 28 units in 2006. After some difficulty with the initial prototype, the first unit, numbered OL912, was delivered on May 1, 2012.

References

{{NYCS rolling stock MPI locomotives New York City Subway Diesel-electric locomotives of the United States EPA_Tier_3-compliant_locomotives_of_the_United_States Standard gauge locomotives of the United States Railway locomotives introduced in 2012