The EMD GP50 all but ended the run of the builder's four-axle road-switchers
although it cataloged the GP60 design in the mid-1980s which was a bit
more successful. By the time the GP50 debuted in 1980 railroads were
much more interested in six-axle power because of their advantages. For
instance, with the two extra axles the locomotive’s weight was more
evenly distributed over the rails causing less wear on them and it also
allowed for increased traction with more axles in contact with the rail.
The EMD GP50, like GP40s and GP40-2s, was built from the body and frame
of the GP38 series. The design featured EMD's latest prime mover at the time, the 16-cylinder model 645F3B, which could produce 3,500 horsepower. It utilized GM's D87 traction motor enabling it to produce a continuous tractive effort of 62,400 pounds and 65,000 pounds continuous.
The most significant difference in the GP50 from earlier designs like the GP40 was upgraded components (like a turbocharger silencer and new type of blower housing) and increased horsepower. It also included features already common on earlier models such as dynamic braking (a system for temporarily employing traction motors as generators and using the resulting electromotive force to slow the train), and an airtight hood that kept out dust, dirt and other particles from reaching internal components. Interestingly there was also a GP59 model cataloged by EMD built between 1985 and 1989.
At only 12-cylinders, using a 710G3A model prime
mover, compared to the standard 16-cylinders, the unit was rated at
3,000 hp. Despite the decrease in horsepower the locomotive was also
more fuel efficient. All were purchased by Norfolk Southern (a total of
36 units) and save for one, the fleet remains in active service for the
railroad. Perhaps the most famous of the units is #4610 which was
commissioned by NS to commemorate the Southern Railway and is adorned in
the predecessor’s beautiful green, white and gold livery. #4610
typically remains in service on NS’s southern lines so be on the lookout
In the end, EMD found just six buyers for the GP50 that who purchased
278 examples of the locomotive.
EMD GP50 Production Roster
|Chicago & North Western||5050-5099||50||1980|
|Southern Railway||7003-7092, 7071-7072 (2nd)||92||1980-1981|
|St. Louis San Francisco Railway (Frisco)||790-799||10||1980|
These railroads included the Santa Fe (45, numbered 3810-3854), Burlington
Northern (63, numbered 3100-3162), Chicago & North Western Railway
(50, numbered 5050-5099), Missouri Pacific (30, numbered 3500-3529),
St. Louis–San Francisco Railway (10, numbered 790-799), and the Southern
who purchased the most (90, numbered 7003-7092, they were the only units
equipped with high hood compared to the common low hood). All the
companies that purchased the GP50 have now been absorbed into other
systems. However, their successors continue to operate the units and as
far as is known none have yet to be sold or scrapped. While the GP50 was not considered a success railroads could count on
their reliability and dependability, which made EMD legendary. In any
event, be on the lookout for them, as there are still many roaming
around out there!
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