EMD "GP50" Locomotives: Data Sheet, Specs, Roster

Last revised: December 17, 2024

The GP50 was EMD's continuation of its four-axle series, incorporating all of the improvements of its predecessor in addition to greater horsepower and continued refinements.

Unfortunately, sales proved lackluster. By the time the model was introduced in May, 1980 the industry had fully moved away from four-axle road power, minus a few holdouts.

In addition, as Louise Marre and Jerry Pinkepank note in their book, "The Contemporary Diesel Spotter's Guide: A Comprehensive Reference Manual To Locomotives Built After 1972," there was hesitation among some railroads to acquire such a high horsepower, four-axle model due to its increased maintenance demands.

Ironically, the earlier GP40-2 actually remained in EMD's catalog a year longer than its successor when Florida East Coast took delivery of #433-434 in December, 1986.

Photos

Burlington Northern GP50 #3112, a few helpers, and a fuel tender move intermodal containers and autoracks through Eola, Illinois on October 16, 1987. Brian Rackley photo.

Overview

The GP50 was EMD's final Geep to carry its model 645 prime mover. The later GP60, produced between 1985-1991 and the last in the series, was equipped with the builder's updated 710G3A engine.

In his book, "Locomotives: The Modern Diesel & Electric Reference," author Greg McDonnell the GP50 was born out of extensive testing carried out in the late 1970s.

Dubbed the GP40X, this testbed variant produced 23 locomotives, which featured a number of experimental features such as a 16-cylinder 645F3 prime mover, high-adhesion HT-B trucks, and a wheel-slip detection system. Interestingly, what ultimately became the GP50 included almost none of these features.

Specifications

The GP50, and its 645F3B engine, offered the greatest output yet of a four-axle model, capable of producing an impressive 3,500 horsepower. The model was designed for fast freight service.

Ultimately, most railroads shied away from the design with only the Southern, Chicago & North Western, Santa Fe, Missouri Pacific, and Burlington Northern purchasing examples. Interestingly, Southern wound up with the largest fleet, 90, which were all equipped with its traditional high, short hoods.

Spotting Features

The GP50 sported a common frame with its predecessors - the GP38 and GP40 series - with an overall length of 59 feet, 2 inches. In addition, the carbodies featured a slightly longer nose and an anticlimber on the front deck.

Despite their many similarities, the '50 is easily distinguishable by its larger rear radiator grilles, which are 8 inches taller. Interestingly, EMD elected not to incorporate the flared radiator grilles utilized on the experimental GP40X, and a feature which defined the big six-axle SD45.

Chicago & North Western GP50 #5059 leads a general merchandise freight westbound at Creston, Illinois on December 18, 1987. Brian Rackley photo.

Reception

The four-axle road-switcher market had cooled considerably by the 1980s. There was no longer demand for such a locomotive in main line service as the industry switched to six-axle models for such assignments. By comparison EMD's bigger SD40/SD40-2 series sold more than 5,000 examples.

The GP50 also suffered from teething issues with its 3,500 horsepower 645F3 prime mover, which further hurt sales. Mr. McDonnell notes this problem was ultimately never corrected.

Data Sheet

Entered Production	5/1980 (Chicago & North Western #5050)
Years Produced	5/1980 - 11/1985
Engine	645F3B
Engine Builder	GM
Horsepower	3500
RPM	900
Cylinders	16
Length	59' 2"
Height (Top Of Rail To Top Of Cab)	15' 7"
Width	10' 4"
Weight	260,000-277,000 Lbs
Fuel Capacity	2600 Gallons
Air Compressor	Gardner-Denver
Air Compressor Model	WBO
Air Brake Manufacturer	Westinghouse
Air Brake Schedule	26L
Trucks	B-B
Truck Type	Blomberg
Truck Wheelbase	9'
Wheel Size	40"
Traction Motors	D87 (4), GM
Primary Alternator	AR15-D18, GM
MU (Multiple-Unit)	Yes
Dynamic Brakes	Yes
Gear Ratio	62:15
Tractive Effort (Starting)	65,000 Lbs at 25%
Tractive Effort (Continuous)	62,400 Lbs at 9.8 mph
Top Speed	65 mph

Production Roster

GP50

Total Built = 278

Owner	Road Number(s)	Serial Number(s)	Completion Date
Southern	7017-7063	786251-1 thru 786251-47	8/1980-11/1980
Chicago & North Western	5050-5099	786257-1 thru 786257-50	5/1980-9/1980
Santa Fe	3824-3839	796317-1 thru 796317-16	3/1981-4/1981
Southern	7003-7016	796321-1 thru 796321-14	9/1980-11/1980
Missouri Pacific	3500-3509	797322-1 thru 797322-10	11/1980-12/1980
Burlington Northern	3100-3109	796331-1 thru 796331-10	12/1980
Santa Fe	3810-3822 (Evens)	806005-1 thru 806005-7	1/1981-2/1981
Santa Fe	3811-3823 (Odds)	806006-1 thru 806006-7	2/1981-3/1981
Southern	7064-7070	807008-1 thru 807008-7	11/1980-12/1980
Missouri Pacific	3510-3525	807023-1 thru 807023-16	1/1981
Southern	7073-7092	807054-1 thru 807054-20	4/1981-6/1981
Southern	7071-7072	807057-1, 807057-2	12/1980
Missouri Pacific	3526-3529	807058-1 thru 807058-4	1/1981
Santa Fe	3840-3854	847057-1 thru 847057-15	4/1985
Burlington Northern	3110-3157	847065-1 thru 847065-48	6/1985-11/1985
Burlington Northern	3158-3162	847073-1 thru 847073-5	11/1985

Most buyers predominanetly used them as intended, in fast freight service, such as the Southern and Chicago & North Western. Of note was the ten ordered by the St. Louis-San Francisco (Frisco) in December, 1980.

By then the railroad was working towards a merger with Burlington Northern and its fleet - except for #3100, which bore full Frisco colors - was delivered in Cascade Green paint.

One final interesting group of BN units carried their on unique trademark; #3158-3162 were equipped with an experimental, oversized "crew cab" designed to house all of the crew at the head-end.

It was not unlike a similar testbed concept built by General Electric, the BQ23-7. This variant of the B23-7 was produced for Seaboard Coast Line in 1978-1979. These also sported an enlarged cab albeit EMD's design enjoyed a more seamless appearance within the overall carbody.

The crewcab never caught on as the caboose was abolished and crew numbers were reduced, making the entire concept redundant. In addition to being the only examples produced they were also the final GP50s outshopped, completed in November, 1985.

Sources

Foster, Gerald. A Field Guide To Trains. New York: Houghton Mifflin, 1996.

Marre, Louis A. and Pinkepank, Jerry A. Contemporary Diesel Spotter's Guide, The: A Comprehensive Reference Manual To Locomotives Since 1972. Milwaukee: Kalmbach Publishing Company, 1989.