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EMD GP18
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The EMD GP18 is a 4-axle diesel-electric locomotive built by General Motors, Electro-Motive Division between December 1959 and November 1963.[1] Power was provided by a 16-567D1 16-cylinder engine which generated 1,800 horsepower (1.34 MW).[1] The GP18 replaced the GP9 in EMD's catalog. 350 examples of this locomotive model were built for American railroads, 40 units were built for Mexican railroads, 12 were built for export to a Brazilian railroad, 2 were exported to Peru, and 1 was exported to Saudi Arabia.
Design and Production
[edit]The GP18 in many ways resembled its predecessors, the GP7 and GP9. It was designed nearly identically to the two previous models, but differed in having a metal grid over its radiator shutters, while the GP7 and GP9 instead incorporated a design described as looking like "chicken wire".[2] Additionally, the GP18 had 50 more horsepower than the GP9, for a total of 1,800 horsepower. The new "18" model number was chosen by EMD to reflect the unit's upgraded horsepower rating.
GP18s could be customized by their buyers: railroads ordered GP18s with either high or low short hoods, with or without dynamic brakes, and in the case of Grand Trunk Western, with the optional addition of steam generators.[2]
Original buyers
[edit]
References
[edit]- ^ Except for one GP18M rated at 1,750 hp (1.30 MW), and 4 rated at 1,500 hp (1.12 MW). See the Original buyers section for more information.
- ^ a b Schafer, Mike (1998). Vintage diesel locomotives. Osceola, WI: Motorbooks International. p. 37. ISBN 0-7603-0507-2. OCLC 38738930.
- ^ a b Marre, Louis A. (1995). Diesel locomotives : the first 50 years : a guide to diesels built before 1972. Waukesha, WI: Kalmbach Pub. Co. pp. 51–52. ISBN 0-89024-258-5. OCLC 34531120.
- Pinkepank, Jerry A. (1973). The Second Diesel Spotter's Guide. Milwaukee, Wisconsin: Kalmbach Publishing. ISBN 978-0-89024-026-7.[page needed]
- Diesel Era. 3 (5). September–October 1992.
{{cite journal}}: Missing or empty|title=(help)[full citation needed] - Extra 2200 South (36). September–October 1972.
{{cite journal}}: Missing or empty|title=(help)[full citation needed] - "EMD Road Switchers: GP18". Utah Rails.
- "EMD Repair Jobs". Utah Rails. September 12, 2014.
- "GM Export Models". Utah Rails. September 22, 2015.
EMD GP18
View on GrokipediaDevelopment
Background and Predecessors
The Electro-Motive Division (EMD) of General Motors began its series of GP road-switcher locomotives in the late 1940s to meet the growing needs of American railroads transitioning from steam to diesel power. The GP7, introduced in October 1949 with 1,500 horsepower, represented EMD's initial foray into versatile, four-axle locomotives suitable for both mainline freight and yard switching, quickly gaining popularity amid the post-World War II economic expansion.[4] By the mid-1950s, escalating freight volumes—reaching 655.9 billion ton-miles in 1956, a 44% rise from 1929 levels—demanded more capable units, prompting EMD to develop the GP9 in January 1954, rated at 1,750 horsepower.[5][6] This model built on the GP7's design, offering enhanced performance for heavier hauls while maintaining affordability and reliability for mixed-service operations. As the decade progressed, railroads faced intensifying market pressures from rising operational costs and competition among diesel builders. American Locomotive Company (Alco) and General Electric (GE) challenged EMD's dominance, with Alco's RS-series models vying for share in the road-switcher segment and GE preparing to expand its offerings beyond components into full locomotives.[7] Railroads sought dependable, cost-effective machines for diverse duties, including freight dragging on secondary lines and yard work, where higher power could offset labor and fuel expenses without the expense of six-axle heavies. EMD responded by refining its lineup to address these demands, emphasizing incremental improvements over radical redesigns to keep pace with evolving freight requirements. In December 1959, EMD announced the GP18 as the direct successor to the GP9, positioning it as an economical 1,800-horsepower option tailored to the era's needs.[1] This model aimed to sustain EMD's market lead by providing a modest power boost at lower acquisition and maintenance costs, appealing to operators navigating competitive pressures and surging tonnage.[8]Design Evolution
The EMD GP18 represented an incremental evolution in General Motors' Electro-Motive Division (EMD) road-switcher lineup, building directly on the design of its predecessor, the GP9, while introducing targeted enhancements for improved reliability and versatility. Launched in late 1959, the model retained the overall hood-unit configuration and 56-foot length of earlier Geeps but incorporated refinements to address operational demands in both freight and passenger service.[1][8] A key innovation was the debut of the 16-567D1 prime mover, a normally aspirated V16 engine variant developed specifically for the GP18, which provided a modest power increase over the GP9's 567C setup while emphasizing maintenance efficiencies through design improvements in the "D" series architecture, such as enhanced structural and moving parts, 5% fuel savings, and reduced maintenance.[8] Visually and structurally, the GP18 featured a metal grid covering the radiator shutters, replacing the "chicken wire" mesh of prior models to enhance cooling airflow and durability under heavy loads.[1] This was complemented by updated radiator grilles, a change shared with the subsequent GP20, which altered the rear profile for better heat dissipation without significantly impacting the locomotive's traditional styling.[3] Hood configurations offered greater flexibility, with the low short hood becoming a standard option for the first time—marking a shift from the high short hood predominant on earlier models—while high hood variants remained available for enhanced crew protection or to accommodate additional equipment.[1] Dynamic braking was optional, integrated with the electrical system to support extended braking in varied terrains when equipped.[1] Production of the GP18 spanned from December 1959 to November 1963 and is categorized into two phases by rail historians, reflecting minor but progressive refinements in external components. Phase I units, built primarily from 1959 to 1962, featured earlier fuel and air tank arrangements along with standard radiator fan shapes similar to late GP9s.[9] Phase II models, introduced after 1962, incorporated flat-top fans, taller 48-inch fan shrouds, and subtle hood detail adjustments, such as revised louvers and access doors, to optimize airflow and accessibility.[9][10] Customization options distinguished the GP18 for specialized roles, including an optional steam generator—such as the Vapor Clarkson #4625—for heating passenger cars, fitted on select domestic units like those for the Grand Trunk Western and export orders to Mexico.[11][1] For international markets, adaptations included modifications for non-standard track gauges, enabling deployment in countries like Brazil, Peru, Mexico, and Saudi Arabia, where 55 units were exported to meet regional infrastructure requirements.[1]Technical Specifications
Prime Mover and Electrical Systems
The EMD GP18 was powered by the 16-567D1, a V16 two-stroke diesel engine developed by General Motors' Electro-Motive Division (EMD). This engine delivered a rated output of 1,800 horsepower at 800 rpm, representing an increase over the preceding 567C variant used in the GP9 through improved combustion efficiency and design refinements. Each cylinder had a bore of 8.5 inches and a stroke of 10 inches, contributing to a total displacement of 9,072 cubic inches. Aspiration was provided by a Roots-type blower, which supplied pressurized air for scavenging and combustion without the use of turbocharging, a feature reserved for later D2 and D3 variants.[11][8][12] The electrical system converted the engine's mechanical power into traction via a direct-current setup typical of EMD's mid-20th-century designs. The main generator, model D22, was directly coupled to the engine crankshaft and produced variable voltage output to drive the four D47 traction motors mounted on the B-B trucks. These motors provided smooth power delivery to the wheels, with continuous ratings supporting the locomotive's 65,000-pound starting tractive effort. Throttle response was managed by an electropneumatic control system incorporating a load regulator, shunt field contactors, and motor alternator sections, which adjusted generator excitation and motor field strength across eight run notches for precise power modulation and efficient operation.[1][11][13] The fuel system supported extended operations with a standard capacity of 1,700 US gallons stored in underframe tanks, equipped with dual filters and strainers to ensure clean delivery to the engine's injectors. For the era, the 567D1 reflected the engine family's emphasis on thermal efficiency through uniflow scavenging and optimized fuel injection timing. This allowed for competitive operational economics, with consumption varying by throttle position—typically lower at partial loads to minimize waste during switching or road service.[11]Chassis, Trucks, and Dimensions
The EMD GP18 employed a B-B wheel arrangement, featuring four axles across two powered trucks that distributed weight evenly for versatile road-switcher performance in yard and mainline freight duties.[1] This configuration, common to General Motors Electro-Motive Division's GP series, supported reliable traction and maneuverability on varied rail networks.[11] The locomotive utilized Blomberg B trucks as standard, a design credited with providing exceptional stability and ride quality through its innovative suspension system, including swing hangers and equalized framing that minimized derailment risks during high-speed operations.[14] These trucks had a wheelbase of 9 feet and 40-inch diameter wheels, enhancing adhesion and durability under load.[1] Principal dimensions encompassed a length of 56 feet 2 inches over the pulling faces of the couplers, a width of 10 feet 3 inches, and a height of 14 feet 6 inches to the top of the cab, with an overall height reaching approximately 15 feet over the roof fans.[11] Loaded weight typically ranged from 240,000 to 249,000 pounds, adjustable based on options such as dynamic brakes or fuel tank capacity.[1] The design adhered to standard gauge of 4 feet 8.5 inches for North American operators, while Brazilian export variants were modified for 5 feet 3 inches broad gauge to suit local infrastructure.[15]Production
Manufacturing Process
The EMD GP18 was manufactured at the Electro-Motive Division's primary assembly plant in LaGrange, Illinois, from December 1959 to November 1963.[1][11] Production was phased across this period, with initial units assembled in late 1959 and continuing through batches in 1960 and subsequent years, allowing for iterative refinements in the build process.[1] The LaGrange facility, operational since 1935, served as the hub for road-switcher locomotive production during this era, leveraging its expansive assembly lines to handle the integration of mechanical and electrical systems.[16] Assembly of the GP18 began with the fabrication of the welded steel carbody, which formed the locomotive's structural core and housed key components.[17] Steel elements, including engine crankcases, were welded together and then cleaned using shot-blasting techniques to ensure surface integrity and remove welding residues.[17] Following carbody construction, the 16-567D1 engine-generator set was installed, comprising the prime mover and main generator aligned for efficient power transmission to the traction motors.[16] Electrical systems, including control circuits and traction motor connections, were then wired and tested on-site within the plant's engineering facilities, often using instrumentation like pressure gauges and fuel scales to verify performance under simulated loads.[17] To enhance efficiency and reduce costs, the GP18 incorporated standardized components carried over from the preceding GP9 model, such as Blomberg B-B trucks and D47 traction motors, which minimized redesign efforts and streamlined supply chains.[11] Specific tooling was developed for the 567D1 engine variant, enabling precise machining and assembly of its 16-cylinder configuration while building on established 567-series production techniques.[17] Quality control measures, including rigorous inspections during welding and post-installation testing, ensured reliability, with innovations like standardized cab structures from the GP9 line contributing to consistent output across the production run.[16]Output and Variants
The EMD GP18 achieved a total production of 405 units between December 1959 and November 1963.[2] Of these, 350 were built for domestic United States railroads, 40 for Mexican operators, and 15 for export markets including 12 to Brazil, 2 to Peru, and 1 to Saudi Arabia.[2] Production was carried out exclusively at the Electro-Motive Division's La Grange, Illinois facility.[18] The standard GP18 variant delivered 1,800 horsepower from its 16-cylinder 567D1 prime mover, serving as a direct evolution from the GP9 with improved power output.[1] For export applications, a GP18M model was built for the Saudi market (1 unit). Some export units, such as those for Mexico, were rated at 1,750 horsepower.[19] Minor phase distinctions appeared during production, such as Phase 1 units from 1959 to 1960 featuring specific hood grille configurations on early builds.[20] Serial numbers for the GP18 ranged from 24924 to 28632 across domestic and export orders.[18] The first unit, Norfolk & Western #915, bore serial number 24924 and was completed in December 1959.[1]Orders and Operators
United States Orders
The EMD GP18 saw significant adoption among United States railroads, with a total of 350 units allocated domestically, representing approximately 86% of the model's overall production.[1] These locomotives were primarily acquired for freight operations, including general merchandise, coal hauling, and yard switching, as railroads sought reliable, non-turbocharged power to complement existing GP9 fleets amid post-World War II expansion. Additional smaller orders from other railroads such as the Grand Trunk Western (10 units), Seaboard Air Line (10 units), and others contributed to the total of 350 units across over 20 U.S. operators. The largest U.S. buyer was the Missouri Pacific Railroad, which ordered 151 units between 1960 and 1963, numbered 400–550 and initially delivered as 4801–4829 for some early batches.[18][21] These GP18s supported the railroad's extensive freight expansion across its Midwestern and Southwestern network, providing versatile power for hotshot freights, locals, and hump yard service; many featured standard high short hoods and dynamic brakes, with later units incorporating AAR Type B trucks and GE traction motors from trade-ins.[1] Norfolk & Western Railway acquired 48 units, road numbers 915–962, delivered from late 1959 to 1961.[18] Optimized for heavy coal service in the Appalachian region, these locomotives emphasized durability in demanding drag freights, with configurations including dynamic brakes and high short hoods to meet the railroad's operational needs in mountainous terrain.[1] Illinois Central Railroad purchased 29 units, numbered 9400–9428, with deliveries spanning 1960 to 1963.[18][22] Intended for mixed freight and passenger applications along its Chicago–New Orleans mainline, the order included both high- and low-short-hood variants, some equipped with steam generators for early mixed-service duties before full dieselization.[1] Smaller orders supplemented these major fleets, such as Chicago & North Western's 6 units (1774–1779) delivered in 1960 for regional freight, featuring high hoods and four 36-inch radiator fans instead of standard larger units.[18] Louisville & Nashville ordered 5 units (460–464) in 1960, configured with low hoods for Southern coal and merchandise traffic.[1] Other modest acquisitions included Rock Island's 23 units for general freight and the Northern Pacific's 9 for logging and bulk hauls, reflecting the GP18's appeal to mid-sized carriers seeking cost-effective road-switchers.[18]| Railroad | Units | Road Numbers | Delivery Years | Primary Rationale |
|---|---|---|---|---|
| Missouri Pacific | 151 | 400–550, 4801–4829 (early) | 1960–1963 | Freight expansion, versatile service |
| Norfolk & Western | 48 | 915–962 | 1959–1961 | Coal hauling in heavy drag freights |
| Illinois Central | 29 | 9400–9428 | 1960–1963 | Mixed freight and passenger duties |
| Chicago & North Western | 6 | 1774–1779 | 1960 | Regional freight operations |
| Louisville & Nashville | 5 | 460–464 | 1960 | Southern coal and merchandise traffic |
