MP 8AC-3

MPI MP8AC-3 R156 (New York City Subway)
The first R156 is delivered to the MTA
Type and origin Power type Diesel-Electric Builder MotivePower Build date 2012-2013 Total produced 28
Specifications Gauge 4 ft 8 1⁄2 in (1,435 mm) Trucks Kawasaki R156 Fabricated Frame Wheelbase 36 ft 0 in (10.97 m) Length 53 ft 3.25 in (16.2370 m) Width 8 ft 8.25 in (2.6480 m) Height 11 ft 5.375 in (3.48933 m) Axle load 29,000 lb (13.2 t) Adhesive weight 100% Loco weight 116,000 lb (52.6 t) Fuel type Diesel fuel Fuel capacity 500 US gal (1,900 l; 420 imp gal) Prime mover Cummins QSK 23G RPM range 600-2100 Engine type Inline-6 Cylinder, four stroke cycle diesel engine Generator Hitzinger SGS7 Traction motors Siemens SITRAC AC propulsion 165 kW (221 hp) per axle Cylinders 6 Cylinder size 3.8583 L (1.0193 US gal; 0.8487 imp gal) Transmission AC-DC-AC Train heating John Deere 5030HF285, 3.0L, 96 hp (72 kW) Loco brake Electro-pneumatic Train brakes Pneumatic
Performance figures Maximum speed 48.27 km/h (30 mph) Power output Gross: 860 hp (641 kW) Traction: ~300 hp (224 kW) @ 24 km/h (15 mph) Tractive effort 20,250 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)
Career Operators New York City Subway Class R156 Number in class 28 Delivered 2012-2013 First run May 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. Instead, the R156 is powered by a 6-cylinder, 800 horsepower Cummins QSK 23 diesel engine. 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.

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.