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R156 (New York City Subway)
OL919 powers the first work train on the Second Avenue Subway
An R156 locomotive on the Second Avenue Subway
Type and origin
Power typeDiesel-Electric
Build date2012–2013
Total produced28
Gauge4 ft 8 12 in (1,435 mm)
TrucksKawasaki R156 Fabricated Frame
Wheelbase36 ft 0 in (10.97 m)
Length53 ft 3.25 in (16.2370 m)
Width8 ft 8.25 in (2.6480 m)
Height11 ft 5.375 in (3.48933 m)
Axle load29,000 lb (13.2 t)
Adhesive weight100%
Loco weight116,000 lb (52.6 t)
Fuel typeDiesel fuel
Fuel capacity500 US gal (1,900 l; 420 imp gal)
Prime moverCummins QSK 23G
RPM range600-2100
Engine typeInline-6 Cylinder, four stroke cycle diesel engine
GeneratorHitzinger SGS7
Traction motorsSiemens SITRAC AC propulsion
165 kW (221 hp) per axle
Cylinder size3.8583 L (1.0193 US gal; 0.8487 imp gal)
Train heatingJohn Deere 5030HF285, 3.0L, 96 hp (72 kW)
Loco brakeElectro-pneumatic
Train brakesPneumatic
Performance figures
Maximum speed48.27 km/h (30 mph)
Power outputGross: 860 hp (641 kW)
Traction: ~300 hp (224 kW) @ 24 km/h (15 mph)
Tractive effort20,250 lbf (90.1 kN) Starting
15,000 lbf (67 kN) @ 12 km/h (7 mph)
7,500 lbf (33 kN) @ 24 km/h (15 mph)
4,200 lbf (19 kN) @ 40 km/h (25 mph)
OperatorsNew York City Subway
Number in class28
First runMay 1, 2012

The MPI MP8AC-3 is a light-weight Diesel locomotive built by the MotivePower division of Wabtec. It was designed from scratch as a work train engine for the New York City Subway system, where it is designated the R156.

The R156 is designed to navigate the clearances and tight turns of the NYC subway, with weight constrained to 112,000 pounds (51,000 kg) 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 power is not used because the third rail is normally turned off at work sites for safety reasons.[3] Instead, the R156 is powered by a 6-cylinder, 800 horsepower Cummins QSK 23 diesel engine.[4] A separate, smaller John Deere Diesel drives a generator to provide auxiliary power, 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 new 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 (CBTC) equipment, which will be installed by June 2017.[5]

The first R156 is delivered to the MTA

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.[3]


Media related to MPI MP8AC-3 locomotives at Wikimedia Commons

  1. ^ "Diesel locomotives delivered to New York subway". Railway Gazette. July 5, 2012.
  2. ^ MP8AC-3 Spec Sheet
  3. ^ a b "MTA New York City Transit Takes Delivery of New Diesel-Electric Locomotive". MTA. May 1, 2012. Retrieved 1 October 2014.
  4. ^ "QSK-23 brochure" (PDF). Cummins.
  5. ^ "MTA 2017 Final Proposed Budget November Financial Plan 2017 – 2020 Volume 2 November 2016" (PDF). Metropolitan Transportation Authority. November 16, 2016. Retrieved November 17, 2016.