MLW M-420

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St Laurent and Atlantic Railway M420W no 3569 front.jpg
Type and origin
Power type Diesel-electric
Builder Montreal Locomotive Works(MLW)
Build date May 1973 - February 1977
Total produced 90 + 8 B-units
AAR wheel arr. B-B
Gauge 4 ft 8 12 in (1,435 mm)
Prime mover Model 251C[1]
Engine type Four-stroke diesel[1]
Cylinders V12
Performance figures
Maximum speed 67 mph (108 km/h)
Power output 2,000 hp (1.49 MW)
Locale North America

The Montreal Locomotive Works M-420 is a diesel-electric locomotive built between 1973 and 1977 in Montreal Quebec, Canada. A total 88 units were built for Canadian railways, including 8 B-units built for the British Columbia Railway; most of production went to the Canadian National Railway.[2] Only seven units were sold outside of Canada, to Ferrocarriles del Estado in Venezuela and Providence and Worcester Railroad in the United States.

The M-420 was one of the first locomotive models (along with the GMD-built GP38-2) to use the wide-nosed Safety (or Comfort) Cab, pioneered by Canadian National Railway. By the early 1990s, variations on this cab design had become the standard of the industry. As with wide-nosed GMD units from the same period, references to the model commonly add a "W" at the end of the model name, but it is not part of the official model designation. Most M-420 units rode on MLW ZWT (Zero Weight-Transfer) trucks.


Other variations of the M-420 were the M-420R, the M-424 built for service in Mexico and the M-420TR switcher. The M-420R was built for the Providence and Worcester Railroad using trade-in parts and rode on Type B trucks, but otherwise resembled the M-420. The M-424 was an M-420 with dynamic brakes uprated to 2,400 horsepower (1.79 MW). The M-420TR was built in two variations, with two M-420TR units sold to Roberval and Saguenay Railway and fifteen slightly different units (sometimes referred to as M-420TR-2) sold to Ferrocarril del Pacifico. Both M-420TR variations bore little resemblance to the other models, with a lowered hood, shorter frame and end-cab design.

Service with CN and BCOL[edit]

CN M-420 units provided service on the eastern side of Canada until their retirement in the late 1990s. By the time they were retired, many units were over 20 years old, and major Canadian railroads were purging their rosters of MLW and Alco locomotives to replace them with newer EMD and GE units. Bombardier-built HR-412 units, purchased by CN and designed as successor to the M-420, were retired at the same time.[3]

Service as power generators in Winter 1998[edit]

During the winter of 1998, a severe ice storm cut off power to many homes and businesses in Ontario and Quebec. CN M-420 3502 was hoisted off the rails by crane and rolled along a street in Boucherville QC in order to provide power in the community. The engine was driven approximately 1,000 feet (305 m) under its own power to the city hall, where it then became a portable power generator.[4] M-420 3508 was also lifted from the tracks to provide power to a school being used as a shelter, but problems prevented this from happening, and 3508 remained on standby. Both engines suffered minor gear case damage and carved grooves in the pavement.

M-420 today[edit]

Following their retirement from CN and BC Rail, some M-420 units were scrapped, but many were sold to shortline railways across North America for continued service. Omnitrax purchased several units, including some of the M-420B units from BC Rail. Larger shortlines such as Omnitrax have begun to scrap or sell their MLW units as a result of increased maintenance and reliability issues. The St. Lawrence and Atlantic Railroad used a fleet of eleven former CN M-420 units as road power from 1998 to 2001. The Great Western Railway in Saskatchewan uses an entire roster of MLW M-420s.[5] Due to the high cost of painting, many M-420s on shortlines still retain their CN livery with the CN logo painted over.

Original owners[edit]


Railroad Quantity Road numbers Notes
Canadian National [7] 80 2500–2579
British Columbia Railway [8] 16 640-647 & 681-688 681-688 are cabless B units
Ferrocarriles del Estado 2 M001 & M002
Providence & Worcester 5 2001–2005 M-420R
Roberval & Saguenay 2 26,27 M-420TR
Ferrocarril del Pacifico 15 522-536 M-420TR

See also[edit]


  1. ^ a b "M420W Data Sheet". Retrieved 2009-02-27. 
  2. ^ "M420W Production". Retrieved 2009-02-27. 
  3. ^ "CN Locomotives - Retired". Retrieved 2009-07-07. 
  4. ^ "M-420W derailed". Retrieved 2009-03-04. 
  5. ^ "Great Western Railway". Retrieved 2009-02-27. 
  6. ^ "Roster". Retrieved 2009-03-04. 
  7. ^ "CN Roster". Retrieved 2009-03-08. 
  8. ^ "BCOL Roster". Retrieved 2009-03-04.