EMD SD50
The
EMD SD50 was a 3,500 hp (2,600 kW)
diesel-electric locomotive built by
General Motors'
Electro-Motive Division. It was introduced in May 1981 as part of EMD's "50 Series", but prototype SD50S locomotives were built from 1980; production ceased in January 1986. The SD50 was in many respects a transitional model between EMD's
Dash 2 series which ran from the early 1970s, especially the successful
SD40-2 and the later high power
SD60 and
SD70 locomotives.
The SD50 was produced in response to increasingly tough competition from
GE Transportation Systems, whose
Dash 7 line was proving quite successful with railroads. While EMD's SD40-2 was a reliable and trusted product, GE's line included locomotives up to 3,600 hp (2,700 kW) with more modern technology, as well as very competitive finance and maintenance deals.
GM-EMD had previously produced 3,600 hp locomotives, the
SD45 and later
SD45-2, but these used huge,
20-cylinder engines with high fuel consumption, and demand for them dropped sharply after the 1970s fuel crises. The SD50 used the same
V16 645 as the SD40-2, but uprated to 3,500 hp from 3,000. This proved to be a step too far; the SD50 model was plagued by engine problems which harmed its sales and caused EMD much harm to its reputation.
The subsequent SD60 model replaced the overstressed 645 engine with a new engine series, the
710.
The SD50's
long hood saw changes from previous EMD models. The overall frame length was increased, and the long hood was made substantially longer. The resistors for the
dynamic brake grid were moved from their previous location above the
prime mover to a new, cooler location in front of the engine compartment air intakes, where they were more effectively separated from the rest of the locomotives' systems.
The
SD50S ("short frame") were prototype units built in December
1980. They were shorter than production locomotives by approximately 2 feet. All of these prototypes were sold to the Norfolk & Western and passed to the Norfolk Southern; they were withdrawn in the early
2000s as non-standard.
The designation also applies to five locomotives built by EMD Australian licensee Clyde Engineering for
Hamersley Iron. These were also shorter than production SD50s, and were equipped with a special double cab roof for insulation against the hot Australian desert sun. When withdrawn from Hamersley Iron service, they were sold to
National Railway Equipment and exported to the U.S. in February 1999 and used in national lease service. They were subsequently sold to the
Utah Railway in June 2001, where they remain.
The
SD50F was a Canadian
cowl unit version equipped with a "Draper taper" (inset section aft of cab for limited rear visibility). 60 were built for the
Canadian National Railway as road numbers 5400-5459.
As of 2005, current owners and operators include:
*
CSX: inherited SD50s from the Baltimore & Ohio, Chesapeake & Ohio, Conrail (split with Norfolk Southern), and Seaboard System.
*
Kansas City Southern: retains the SD50s it originally bought.
*
National Railway Equipment Company (NREX): lease operator owning ex CSX ex Conrail locomotives.
*
Norfolk Southern Railway: Its own purchases, and some of Conrail's.
*
Reading, Blue Mountain and Northern Railroad: 6 units purchased from the
Union Pacific Railroad.
*
Union Pacific Railroad: inherited SD50s from the Missouri Pacific (60, bought immediately pre-merger and delivered in UP colors), the Chicago & North Western (35 units) and the Denver & Rio Grande Western via the Southern Pacific (17 units).
* Lytle, Stan.
EMD SD50 list. Retrieved on
February 16,
2005.
* TrainWeb.com.
The Unofficial EMD homepage. Retrieved on
January 7,
2005. Contains fairly complete builders' records for EMD production.
