The MLW/ALCO FP-4 is a type of 1,800hp four-axle diesel locomotive which consists of 2 forms: the FPA-4 "A" unit, and the "B" unit being the FPB-4.


A CN (Canadian National) ALCO FPA4 leaving Montreal, Quebec in Canada.

The locomotives were powered by the then-new ALCO 12-251 engines, and were some of the first new locomotives to use the particular prime mover.

The FP-4 was only built for CN. 34 FPA-4 units and 12 FPB-4 units were produced.


To supplement CN's major restructuring of passenger services after World War II, CN purchased a number of FA-2 locomotives from ALCO. However, the 244 prime mover proved unreliable. CN then asked MLW/ALCO for a new and improved version for their passenger trains, and MLW answered with the FPA-4 and the FPB-4, which contained the newer, much more reliable ALCO 251.

CN numbered these locomotives as 6760-6793 (FPA-4) and 6860-6871 (FPB-4). The FPA-4 was assigned class MPA-18a, and the FPB-4 was assigned class MPB-18a. The class breakdown is as follows: Montreal Locomotive Works, Passenger, A-unit or B-unit, Horsepower (1800), series (a). These locomotives were initially assigned to the Eastern Transcon routes, such as the Ocean. However, in later years they did make it out west, first on the Super Continental, then, after the formation of VIA, the Canadian. From delivery to retirement, they (and CN's FP9 fleets) were also a common sight on the Quebec City-Windsor Corridor

The FP-4 locomotives were some of the most powerful locomotives in ALCO's FA series which were offered at the time. Though; however, CN ended up being the only customer, as others favored EMD's products instead of ALCO's new product.

Retirement and preservation Edit

The CN's fleet of FP-4 units were retired in the early 1990s, after operating in service with CN and VIA for about 30 years. They were retired supposedly because new law states that every leading locomotive must have Reset Safety Controls installed, following a deadly accident at Hinton, Alberta on Februrary 8, 1986, where 27 people died in what is still considered to be the worst train wreck in Canadian history. However, the new law was only partially the reason to blame; in 1990, VIA saw its operating budget slashed by 55% from the Canadian government. As VIA now currently lacks the funds to upgrade them according to the new law, it was decided to sell these locomotives rather than to rebuild them.

Many FPA-4s survive today, most notably on the Napa Valley Wine Train and Cuyahoga Valley Scenic Railroad.


Ironically, as a result of its original form being long-gone, Cuyahoga Valley Scenic Railroad (CVSR) #800; a former CN FPA-4, was actually painted in B&O (Baltimore And Ohio) livery to dedicate #800: a long-lost ALCO FPA-2 (a similar type of locomotive model built ALCO) which was once owned by the B&O and saw service around the Cuyahoga Valley region around Akron, Ohio on the B&O's Akron passenger subdivisions (now part of CSX).

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