1. Home
 ›
2. Diesel Locomotives
 ›
3. GP9

The "GP9": The Blockbuster First-Generation Diesel

Last revised: December 19, 2024

By: Adam Burns

The GP7 was Electro-Motive's first, true road-switcher.  The locomotive's broad ranging capabilities allowed railroads to utilize it in a multitude of assignments; road service, switching, branch line, passenger, and even commuter.

Its redundancy, coupled with EMD's impeccable reputation, made it an immediate success with more than 2,700 examples produced.

The following GP9 was nearly identical in appearance.  However, the model, as part of EMD's so-called "9 Line," offered greater horsepower and even better reliability. 

By the mid-1950s, and the GP7's success, railroads had largely lost interest in handsome streamlined diesels.  The road-switcher, while less elegant in appearance, could perform many more tasks and was safer for crews.

The GP9 saw even higher sales than its predecessor and remaining steam holdouts like the Norfolk & Western purchased large fleets of the model to finally retire the iron horse forever from remaining Class 1 systems.

Today, hundreds of GP9s remain in operation on short lines, or in use at tourist railroads. In addition, others are preserved at various museums and historical societies.  

Photos

Lehigh Valley GP9 #301, wearing one of the road's many late-era liveries, is seen here at the road's terminal in Sayre, Pennsylvania on September 9, 1972. Bob Wilt photo. Warren Calloway collection.

Overview

The first GP9 completed was Milwaukee Road #2400 in January, 1954.  As part of EMD's latest "9 Line," which also included the F9, SD9, and E9 the model continued the builder's efforts at continously improving its product.

As Brian Solomon notes in his book, "EMD Locomotives," the model was the most advanced, rugged, and reliable in the series sporting EMD's latest prime mover and other internal components.

The 567C power plant was the latest in the series up until that time.  Its upgrades included a redesign of the engine crankcase to withstand a greater beating in daily service, replacement of water seals susceptible to leaking on older model 567s, and an improved cooling circuit.

A pair of Southern Pacific GP9's, #5684 and #5711, lead a westbound/southbound freight over the big lift bridge spanning the Carquinez Strait near Martinez, California circa 1956. Gordon Glattenberg photo. American-Rails.com collection.

Specifications

EMD's locomotives were reliable, easy to maintain, and efficient. Once again it was EMD's chief engineer Richard "Dick" Dilworth who laid out the general design of the GP7, and the company's styling department headed by John Markestein put the finishing touches on the new model.

Rio Grande GP9 #5913 lays over with other power next to the roundhouse in Pueblo, Colorado during the 1970s. American-Rails.com collection.

The GP9 carried the appearance of its predecessor but offered new features as previously mentioned. The 567C featured a slight, 250 increase in horsepower over the earlier GP7. To achieve this, engineers increased rotational speed from 800 to 835 rpm as the engine's bore and stroke remained the same.

It was also equipped with a new traction motor, the model D37.  EMD offered six different gear ratios for the GP9, depending on a railroad's need.  They were, of course, most often used in freight assignments, but were also available with optional steam generators for passenger or freight assignments.

Chicago, Burlington & Quincy GP9 #288 is seen here at work in Kansas City, circa 1965. American-Rails.com collection.

Spotting Features

The GP7 and GP9 were nearly identical and it required a keen eye to spot the notable differences.  The most recognizable was the addition of a stainless steel, "GP9" model nameplate located just forward of the battery box ahead of the cab.

This cosmetic feature was first offered on the "9 Line" and available upon customer request.  Much more inconspicuous characteristics included louver locations; the GP7 featured three directly below the cab, as well as two vertical louvers just below the radiator shutters near the end of the long hood.

The GP9, by contrast, included only one (or no) louvers below the cab and one beneath the radiator shutters.  EMD also made slight changes during production; later variants lacked side skirting over the fuel tank and one large cooling fan at each end of the roof, replacing four found in earlier models.  

Pennsylvania GP9B #3808-B (built as #7183-B) and GP9 #7269 at East Peoria, Illinois, circa 1967. American-Rails.com collection.

Finally, some final examples were built with low, short hoods; an indication of the future.  As Gerald Foster notes in his book, "A Field Guide To Trains," over the years such spotting features became somewhat unreliable in discerning model types as many were heavily rebuilt or modified.

Data Sheet

Production Roster

Total Built = 4,092

Export

General Motors Diesel (GMD)

GP9B

Total Built = 165

Rio Grande GP9 #5921 at Pueblo, Colorado during the 1970s. American-Rails.com collection.

Most GP9s (and GP7s) were built to operate short hood forward, although this was not always the case.  As Bob Hayden notes in "Diesel Locomotives: Cyclopedia, Volume 2 (Model Railroader)" like the New York Central and Canadian National specified long hood forward operation.  In addition, many roads ordered both GP7s and GP9s with dual control stands. 

Interestingly, both the PRR and Union Pacific requested cabless GP9Bs; the former picked up 40 examples while the latter acquired an impressive 125.  One of the PRR's units can be seen in the above photo.

The GP9's extreme versatility is, of course, what made them so successful, and many continue to be found today in freight service on both short lines and regionals (as well as museums and tourist lines).

Western Pacific GP9 #708, F7A #921, and a GP40 appear to be tied down with their train at Milpitas, California, circa 1979. Mike Bledsoe photo. American-Rails.com collection.

Sources

• Marre, Louis A. Diesel Locomotives: The First 50 Years, A Guide To Diesels Built Before 1972.  Milwaukee: Kalmbach Publishing Company, 1995.

• Pinkepank, Jerry A. Diesel Spotter's Guide.  Milwaukee: Kalmbach Publishing Company, 1967.

• Schafer, Mike. Vintage Diesel Locomotives. Osceola: MBI Publishing, 1998.

• Solomon, Brian. American Diesel Locomotive, The. Osceola: MBI Publishing, 2000.

• Solomon, Brian.  EMD Locomotives.  Minneapolis: MBI Publishing Company, 2006.

• Trzoniec, Stanley W.  Vintage & Modern Diesel Locomotives: Prime Movers Of America.  Minneapolis:  Voyageur Press, 2015.