Locomotives / Train Sets


Diesel-Electric Locomotive

Series: "50 Series"

Entry Last Edited: 01/17/2024 | Content ©www.RailRoadJunction.net | The following text is exclusive to this site.
Specifications [+]
Four-hundred thirty-one total SD50 units were completed into mid-1987 and these went on to serve primarily North American operators.
American railway freight has, for decades, been moved primarily by way of diesel-electric power. The EMD SD50 became one such contributor, built across 431 total examples from the period spanning 1980 to 1987. The locomotive was constructed under the Electro-Motive Diesel (EMD), General Motors Diesel (GMD), and Clyde Engineering brand labels for its run. It continues to serve in some number today (2023) where some have even been rebuilt to match the improved SD40-2 standard.

The SD50 was a direct response to General Electric's "Dash 7" line's popularity with railway customers in America. Hence the SD50 was drawn up to counter this reach and was presented as an improvement to the earlier troubled, gas-guzzling SD45/SD45-2 models. The SD50 continued use of the SD40-2's engine which, by this time, had been updated by engineers to output at 3,500 horsepower for better hauling capability (and operate more in line with the powerful GE offerings of the time) though not without reliability issues. Other changes resulted in enhanced maintenance accessibility and increased dimensions.

The locomotive, as built, was given an overall length of 71.1 feet and powered by the EMD 16-645F3B V16 diesel unit for a total rated output power of 3,500 horsepower. In November 1984, this was increased to 3,600 horsepower though conversions have also seen this derated to 3,000 horsepower. Traction alternators were either the AR11A-D14 or AR16A-D18 sets, both produced by EMD.

Eventually, two sub-variants of the SD50 line were added to the mix, these being the SD50S ("short frame") and the SD50F.

S-models began life as six prototype forms in December 1980 and the design was essentially shortened by some two feet in length when compared to the original SD50. These went on to be operated by Norfolk & Western before falling under the Norfolk Southern brand operating label. Clyde Engineering of Australia built five SD50S models with special attention paid to crew comfort in hot operating environments and were operated into 1995 before being purchased and shipped stateside for the National Railway Equipment Company. These locos changing hands a few more times under various operators in the United States.

The F-model was a modified version developed exclusively for Canadian railway service. Sixty of the type were built for hauling powerhouse Canadian National, notable for having the rear walking areas completely covered over in hardened bodywork (the term 'cowl unit' being applicable here, though the modification being more common with passenger-haulers than freight-movers). Early troubles limited total output power to 3,300 horsepower and their reliability issues were never truly ironed out.

Some ten total operators utilized the original SD50s with Conrail being the largest at 135 total units in the fleet. The SD50S short-framed models were purchased only by Norfolk & Western Railway across six units while the SD50F (cowl units) were taken on by CN across an impressive sixty examples.

One of Chicago & North Western's fleet, S/N 7009, was donated to the Illinois Railway Museum in October 2022 for preservation.

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Specifications [ EMD SD50 ]

GM Electro-Motive Diesel (EMD) / General Motors Diesel (GMD) - United States; Clyde Engineering - Australia

United States
1980 - 1987
Production Run

431 units
Production Total
Train driver seating position graphic

Driver Position
21.7m | 71.2 ft
NOTE: May include length of entire train set
Locomotive power source graphical icon
Power Source
1 x EMD 16-645F3B V16 16-cylinder diesel engine with AR11 alternator.
Engine / Drive Source
3,500 hp
Rated Output Power
Wheel Arrangement
(Loco Facing Left)

Series Variants
SD50 - Base Series Designation.
SD50S - Shortened-frame prototype forms of late-1980; six examples completed and operated by Norfolk & Western.
SD50S - Five examples by Clyde Engineering of Australia.
SD40E - Rebuilt SD50S prototypes by Juniata Shops (Norfolk Southern).
SD50F - Canadian market form; 3,300hp to 3,500hp output; 60 examples built.
Operating Countries
Australia; Canada; United States

National flag of Australia National flag of Canada National flag of the United States
Customers / Operators:
Baltimore and Ohio; Canadian National; Chicago and North Western; Chesapeake and Ohio; Conrail; Denver and Rio Grande Western; Hamersley Iron (Australia); Kansas City Southern Railway; Missouri Pacific Railway; National Railway Equipment (NREX); Norfolk Southern; Norfolk and Western Railway Seaboard System Railroad
NOTE: Includes both past and present

Image of the EMD SD50

Image of the EMD SD50
Portside view of an EMD SD50 diesel-electric locomotive in NREX livery; color.
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