SD50/50F
From RailroadfanWiki
SD50
The Electromotive Division SD50 is a 6 axle, 3,500 HP diesel-electric locomotive built by EMD from 1981 to 1986. It's 16 cylinder 645F3B engine could be rated between 3,300 HP and 3,500 HP. It was the last engine to use the 645 engine, the 710 being introduced on the subsequent SD60. The SD50 is viewed as a transitional model between the SD40-2 and the more reliable micro-processor equipped SD60. The SD50 was markedly different from it's SD40-2 predescessor, the engine was longer and more streamlined in appearence. The dynamic brake blister that had been on EMD hood units since the GP7 was gone, the dynamic brake grid being moved behind the cab with radiators mounted on the sides of the hood. 427 units were built, Conrail had the most with 135 units. While most were built with HTC trucks, Conrail ordered 2 orders of SD50's with older Flexicoil trucks.
The SD50 was not as reliable as the SD40-2. 3,500 HP was too much for the old 16 cylinder 645 engine, and the units suffered from mechanical issues. Many SD50's surviving today have been derated to 3,000 HP, essentially making them SD40-2's (CSX's derated SD50's are classified as "SD50-2's", while NS's rebuilt SD50's are called "SD40E's"). The SD50's suffered many electrical and mechanical problems, and as a result GE outsold EMD for the first time with their Dash 8 line, and has continued to outsell EMD ever since.
6 SD50S's were built as test units for Norfolk Southern. They were 2 feet shorter than standard SD50's, and have all been retired. EMD also built several SD50S's as export models.
SD50F
The Electromotive Division SD50F is a Canadian variant of the SD50 built by EMD affiliate GMD in Ontario for Canadian National railway. The SD50F was a cowled version of an SD50, and used all the same parts, save for the actual locomotive body. The cowl design used on the SD50F (and later the SD60Fs and 8-40CMs) was a new one called the "Draper Taper", named after it's designer, the body tapered inward slightly behind the cab (which was a Canadian saftey cab) for better rearward visability. 60 SD50F's, were built, CN numbers 5400-5459, all rated at 3,500 HP. As of 2009, CN has retired/stored all SD50F's.
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