MPI MPXpress

MP36PH-3S

The MP36PH-3S uses a 16-cylinder EMD 645F3B diesel engine as its prime mover, capable of generating 3,600 hp. Head-end power (HEP) is generated by a static inverter that receives its power through connections to the prime mover (hence the "S" (static) designation). Compared to a locomotive with a separate HEP generator, the prime mover must constantly maintain a higher RPM in order to supply power to the passenger cars. The setup is simpler but leads to higher noise levels and higher fuel consumption.

When providing the maximum 500 kW HEP load, maximum traction power is reduced to 2,930 hp since HEP generation diverts some power from the prime mover.

The MP36PH-3S was the first variety of MPXpress locomotive to be built and the launch customer was Metra, a commuter railroad in the Chicago area. Metra ordered 27 of these locomotives in 2001, which were built and delivered between 2003 and 2004. Fourteen were to replace the railroad's aged F40C fleet, while the rest were for fleet expansion. Metra is currently the only operator of the MP36PH-3S variant of the MPXpress.

When the locomotives were first delivered, the onboard computer systems proved problematic. At one point in 2004, because Metra had so many MPXpress locomotives out of service, two F40Cs had to be placed back into service for a short time. After fixes were implemented, the locomotives became the workhorses of Metra's fleet.

Conversion to MP36PH-3C specification

Starting in 2015, Metra is converting its MP36PH-3S locomotives to the MP36PH-3C specification by removing the static inverter and replacing it with a separate HEP generator. This is being done in an effort to reduce noise pollution and boost fuel efficiency. There are plans to convert at least ten, if not all MP36PH-3S locomotives. Metra's MP36PH-3C locomotives all have extended radiators to supply the extra cooling for the Caterpillar generators.

MP36PH-3C

The MP36PH-3C has the same EMD 645F3B prime mover as the MP36PH-3S model, but with a separate head-end power generator, a Caterpillar C-27 diesel engine (hence the "C" (Caterpillar) designation). In this arrangement, when providing HEP, the full 3,600 hp from the prime mover is available for traction, and the prime mover is allowed to idle at a lower RPM. Having two engines is more complex, but results in lowered noise emissions and lower fuel consumption.

The launch customer for the MP36PH-3C was Caltrain, a commuter railroad in the San Francisco Bay Area. Caltrain ordered 6 of these locomotives in 2003, which were built and delivered that same year. This locomotive has gone on to become the most popular MPXpress variant, with 100 delivered to nine different customers.

MP40PH-3C

The MP40PH-3C introduced a new prime mover, the larger 16-cylinder EMD 710GB series diesel engine, capable of generating 4,000 hp. The MP40PH-3C also uses an EMD alternator and traction motors.

The launch customer for the MP40PH-3C was GO Transit, a commuter railroad in the Toronto area.

The MP40PH-3C was developed in response to a bid request from GO Transit for locomotives capable of generating 4,000 hp, hauling 12 passenger cars and traveling at speeds up to 93 mph. Motive Power and GE Transportation responded to the request, with Motive Power being selected as the winning bidder. GO Transit placed an order for 27 locomotives in 2006, which were built and delivered between 2007 and 2008. GO Transit has gone on to order a total of 67 MPXpress locomotives.

Tier 3 compliance

Motive Power upgraded the MP40PH-3C to comply with the EPA's more stringent Tier 3 emissions standard, which went into effect in 2012. The first customer for the Tier 3 compliant locomotives was Sound Transit, which purchased three units which were delivered in 2011, to be used on its Sounder commuter rail service in the Seattle area. Per federal law, all locomotives delivered between 2012 and 2014 are Tier 3 compliant.

MP32PH-Q

The MP32PH-Q was built for SunRail to similar specifications as new MPXpress locomotives, but are rebuilt and refurbished from units that had previously operated on MARC as GP40WH-2 locomotives. Inside the locomotive, the 3,000hp EMD 16-645 prime mover has been rebuilt and electronics have been upgraded using the same equipment as other MPXpress locomotives. On the exterior, the MP32PH-Q retains the hood unit layout of the former GP40WH-2, but a new MPXpress cab replaces the original cab.

MP54AC

The MP54AC is the latest locomotive in the MPXpress family designed to both meet the EPA's stringent Tier 4 emissions standard and offer higher performance than the MP40PH-3C. It can be built as new or as a Tier IV repower to existing MPXpress locomotives. The MP54AC uses a pair of Cummins 16-cylinder QSK60 engines rated at 2,700 hp each (5,400 hp total), making it the most powerful diesel passenger locomotive in North America. During periods of low power demand, the locomotive can operate on just one engine to reduce noise pollution and boost fuel efficiency. The MP54AC competes with the EMD F125 and Siemens Charger.

GO Transit was the launch customer for the MP54AC. The first prototype unit was built by converting a MP40PH-3C owned by GO Transit (unit 647). Motive Power removed the EMD prime mover and HEP motor and replaced them with the twin Cummins engines. Heavy modifications were made to the body to accommodate extra air intake and exhaust stacks. Unit 647 was delivered to GO Transit late 2015 and was seen under testing on December 12, 2015.

Initially GO Transit had planned to convert a total of ten MP40PH-3Cs to the new MP54AC standard, but later opted to instead order 16 MP54AC locomotives and keep the remaining MP40PH-3Cs intact. There are also plans to use the new MP54AC locomotives to replace remaining F59PHs left in service.