Diesel Locomotives, Extinguishing The Fire Of Steam

Diesel locomotives, technically known as diesel-electrics, came into widespread use here in the United States with the development of the Electro-Motive Corporation’s (EMC, later to become the General Motors' Electro-Motive Division, or EMD) EA/EB design, first tested on the Baltimore & Ohio Railroad (B&O) in the late 1930s. The diesel-electric locomotive would also become a major milestone in technological development for North American railroads as it symbolized the end of the only motive power type (aside from electrics) to be used in the industry up until that time, the steam locomotive. 

Two Milwaukee Road SD40-2s, #134 and #154, lead a westbound freight through Oakdale, Wisconsin on September 18, 1982.

The mechanics of diesels are rather straightforward, although it is commonly mistaken that the diesel engine itself propels the locomotive, which is not the case. While the diesel engine is the prime mover the energy it creates drives an electrical generator, which in turn drives the traction motors found within the locomotive’s trucks that actually turns the wheels (or the mounts which sit over the axles) and propels unit forward. The diesel engine itself has no connection to the actual motion of the wheels and in essence the locomotive is an electric locomotive which carries its own power source on board. 

Common Designs

The Switcher, Performing Yard Work And Other Light Duties 

The Cab Unit, The Era Of Streamlining

The Standard Road-Switchers, Tasked With Handling Heavy Freights 

The Unique Transfer Switcher Variant 

Below you can find each manufacturer and a number of their most popular first and second-generation diesel locomotive models. Simply click on their link to learn more about them. 

American Locomotive Company (Alco)

A History Of The American Locomotive Company, Alco 

Alco's Canadian Arm, The Montreal Locomotive Works 

Alco's First Cab Design, The Experimental Black Maria 

Competing With EMD's F Model, The FA Series 

The Beautiful PA Series

The Century Series, Alco's Final Road-Switcher Catalog

The Early DL Design, The Company's Initial Cab Series

The RS-1, The Road-Switcher Is Born

The RSD-1, For The Army

The Joint EMD/Alco MRS-1 Road-Switcher For Military Service 

The RS-2, Following Its Predecessor

The RSC-2 Variant

The RS-3, Alco's Best-Selling Road-Switcher

The RSD-4, Continuing The Six-Axle Design

The RSD-5, High Sales Than Its Predecessor

The RSD-7, Alco Struggles In The Road-Switcher Market

The RS-11, Unable To Keep Pace With EMD

The RSD-12, Another Poor Seller

The RSD-15 "Alligator"

The RS-27, Striving For Success

The RS-32, Another Failure

The RS-36, Last In The Road-Switcher Series

The C-415, A Most Unique Design

The C-420, Introducing The "Century" Series 

The C-424,  A More Powerful But Unsuccessful Model 

The C-425, Still Lagging Behind 

The C-430, The Final Four-Axle Century 

The C-628, The First Six-Axle Century 

The Big C-630 Line

The C-636, Powerful Yet Unpopular 

The C-643DH Diesel-Hydraulic, An Experimental For SP 

The C-855, A Beast Built For Union Pacific

The S-1, Alco Finds Success With The Switcher

The S-2, Continuing Strong Sales

The S-3, Another Moderate Success

The S-4, Yet Another Home Run

The S-6, The Final Standard-Model Switcher

The Intriguing T-6, "Transfer" Design

The Joint General Electric/Alco Gas Turbine Design

Erie Lackawanna RS-3 #1026 rests between assignments at the engine terminal in Akron, Ohio on June 24, 1975.

Diesel-electric locomotives have been around in one shape or form since 1918 when the American Locomotive Company (Alco) joined with General Electric and Ingersoll-Rand to produce a motor car design for the Jay Street Connecting Railroad, #4. Designated as model GM-50 it was essentially a diesel powered motor car, somewhat similar to an interurban car, and built in conjunction with Alco and Ingersoll-Rand. Later, in 1924 the three companies built a 300 hp, 60-ton boxcab design that would be purchased by the Central Railroad of New Jersey, followed by the Baltimore & Ohio Railroad. 

Baldwin-Lima Locomotive Works (BLW)

A History Of The Baldwin Locomotive Works 

The Lima Locomotive Works, A Future Baldwin Partner 

The Whitcomb Locomotive Works, A Division Of Baldwin 

The VO-660, Entering The Switcher Market 

The VO-1000, Baldwin's Top Sales Performer

The DS-4-4-660, Replacing The "VO" Series 

The DS-4-4-750, Offering 750 Horsepower

The DS-4-4-1000, The Final "DS" Series Model0

The S-8, A New Model Of Switcher

The S-12, Baldwin's Final "Standard" Line Switcher 

The DT-6-6-2000, A Unique Design For Transfer Service

The RT624, The Final Transfer Variant 

The DRS-4-4-1500, The First Road-Switcher 

The DRS-6-4-1500, Struggling To Find Sales

The DRS-6-6-1500, The Most Successful In The "DRS" Series

The AS16, Unveiling The "Standard" Line

The AS416, Fighting To Maintain Market Presence

The Six-Axle AS616, The Most Successful "Standard" Line Model

The RS12, The Light Road-Switcher

The "Baby Face" DR-4-4-1500, Baldwin's First Cab Model 

The DR-6-4-1500, A Failed Design 

The DR-6-4-2000, Another Flop 

The RF16 "Shark," Offering Improved Sales 

The DR-12-8-3000 "Centipede," A Singularly Baldwin Design 

A History Of Baldwin's "Sharknose" Carbody 

The Company's First Carbody Design, The Unpopular "Baby Face" 

Several Pittsburgh & Lake Erie U28Bs including #2811, #2804, #2813, and #2808 are far from home as they as they roll light through the Delaware & Hudson's SK Yard in Buffalo, New York (thanks to recently acquired trackage rights into the city) on November 19, 1983.

The B&O also has the distinction of being the first railroad in the country to purchase a diesel-electric passenger locomotive in 1935 from EMC (B&O #50). While these early designs were somewhat successful and new diesel switch engines were becoming quite popular from makers such as Alco, it would not be until the development of EMD’s legendary E and F models (which followed the EA/EB design they were nicknamed "covered-wagons") to pull heavy passenger and freight consists did the diesel-electric locomotive really come of age and overtake the steam locomotive as the dominant means of moving freight across America’s rails. 

Fairbanks-Morse (FM)

A History Of Fairbanks-Morse's Locomotive Division 

The Canadian Locomotive Company, FM's Canadian Arm

The H10-44, A Strong Sales Performer

The H12-44 Switcher, FM's Bestseller 

The H15-44, The Light Road-Switcher

The H16-44, FM's Most Successful Road-Switcher 

The H20-44, A Compact, High Horsepower Model

The Six-Axle H16-66, "Baby Train Master" 

The Powerful H24-66, "Train Master," Too Far Ahead Of Its Time 

The "Erie Builts," FM's Passenger Model

The Consolidated Line, "C-Liners" 

CSX Train #134 rolls along the Mountain Subdivision at Pinto, Maryland led by AC4400CW #5111 on October 5, 2009.

It would take the diesel-electric locomotive nearly fifty years to equal the horsepower output of the steam locomotive during its technological height. However, diesels offered an advantage that far surpassed steamers and it was the deciding factor in them becoming the prime choice of motive power, efficiency. Diesels required far less maintenance in terms of overhauls (scheduled time in the shops for routine maintenance) and refueling (no longer were there frequent stops requiring water and coal/oil), which allowed them to be spending much more time moving freight and paying the bills. 

General Electric (GE)

A History Of General Electric's Many Locomotive Models 

A Look At GE's First Road-Switcher Series, The Classic "U-Boat" 

The U18B "Baby Boat," The Light Road-Switcher 

The U25B, GE's Enters the Locomotive Market 

The U28B, Following Its Predecessor 

The Modestly Successful U30B 

The U33B, The Fourth U-Boat 

The U36B, Purchased Only By The SCL And Auto-Train 

The U23C, A Light-Powered Late-Era Design 

The U25C, The First Six-Axle 

The U28C, Adding Power 

The U30C, Providing EMD Competition 

The U33C, Driving Alco Out Of The Market 

The U36C, The Final Cataloged U-Boat 

The U50, An Experimental, 5,000 Horsepower Monster 

Another Experimental, Union Pacific's Enormous U50C 

The Joint General Electric/Alco Gas Turbine Design

The B23-7, Replacing The U-Boat 

The B30-7, Picking Up Sales 

The B36-7, Four Axles And 3,600 Horsepower 

The Popular Six-Axle C30-7, Looking To Supplant EMD 

The Powerful C36-7 

The "Super 7" Series Rebuild Program 

The B32-8 Series, Offering 3,200 Horsepower 

The B39-8 Variant, A Rare, Unsuccessful Design 

The B40-8/W, The Last Four Axle 

The Six-Axle, 3,900 Horsepower C39-8

The C40-8/W Series, Surpassing EMD 

The C40-9/W Variant

The C44-9W, Cementing Its Dominance 

The Popular AC4400CW, Designed For Drag Service 

The AC6000CW, Providing 6,000 Horsepower 

Continuing Its Reign, The Evolution Series 

Westbound CSX Train #N626-27 departs Clifton Forge, Virginia with an empty string of coal hoppers led by SD70ACe #4844 on March 25, 2007.

General Motors’ Electro-Motive Division (EMD)/Electro-Motive Diesel

A History of General Motors' Electro-Motive Division (EMD), Today's Electro-Motive Diesel

EMD's Canadian Division, General Motors Diesel 

Early EMC Switchers: SW, SC, NW, NC 

The Interesting "Cow-Calf" Switcher Designs

The NW2, Offering Early Success

The SW1, Featuring The New 567 Prime Mover 

The SW7, Another Favorite

The SW8, Providing Slightly More Power

The SW9, Maintaining Strong Sales

The 900 Horsepower SW900

The SW1000, Showcasing EMD's Second-Generation, 645 Prime Mover

The SW1001 Variant, Fixing A Problem

The SW1200, Continuing EMD's Dominance

The SW1500, Another Bestseller

The MP15DC/AC/T Series, EMD's Last Switchers

A General History Of The Passenger E Series 

The Early EA/E1/E2 Models

The E3, Replacing The Winton With The 567

The Seaboard Air Line's E4

The Burlington's Sleek, Stainless-Steel E5

The E6, The First Production Passenger Model

Rock Island's Unique AB6, Designed For The "Rocky Mountain Rocket"

The Successful E7, Debuting EMD's Iconic "Bulldog Nose" Carbody

The E8, EMD's Continues Its Reign

The E9, Last In The Series

A Look At EMD's Popular Freight Line, The F Series 

The FT, Replacing The Steam Locomotive

The Rare F2

The F3, Cementing Diesel's Dominance

The F7, The Blockbuster Covered Wagon

The Passenger Model FP7

The F9, Closing Out The "Bulldog" Design

New Haven's Unique, Dual-Service FL9

The F40PH Series

The "Cowl" F45 Series

The Notorious SDP40F Passenger Variant

The BL2, The GP Series Predecessor

Great Northern's GP5

The GP7, Debuting An Icon

The GP9, Another Phenomenal Road-Switcher

The Versatile GP15 Series

The Modestly Successful GP18

The Rare RS1325

The GP20, Entering The Turbocharged Age

The GP30, Offering A Timeless Look

The GP35, Finding Continued, Second-Generation Success

The GP38 Series, EMD Hits The Mark Again

The Successful GP40 Series

The Unsuccessful GP50

The GP60, Last Of The Geeps

The Joint EMD/Alco MRS-1 Road-Switcher For Military Service 

The SD7, EMD's First Six-Axle Road-Switcher

The More Successful SD9, "Cadillac"

The SD18, A Late-Era First-Generation Model

The SD24, EMD's First Turbocharged Road-Switcher

The SD35, Growing Six-Axle Popularity

The SD38 Series, Featuring The New 645

The Blockbuster SD40/SD40-2 Series, The Gold Standard

The Powerful, 20-Cylinder SD45 Series

The SD50, Electro-Motive's Downfall

The SD60 Series, Attempting To Rebound

The Successful SD70 Series

The SD75M/I Variant

Conrail's SD80MAC

The 6,000 Horsepower, But Problematic SD90MAC

Electro-Motive's Latest Model, The SD70ACe

Odd/Unique Designs

B Units 

C&NW's Crandall Cabs 


DDA40X, "Centennial" 

Draper Taper 

Krauss-Maffei ML-4000 


Rock Island's AB6 


Tunnel Motors 

SP H24-66 Train Master #3028 heads up local commuter train #128 as it pulls away from the 3rd & Townsend station in San Francisco during August of 1973. Today, the depot and tracks are no more.

Notable Prime Movers

Alco's Model 244 

Alco's Model 251 

EMD's Model 567 

EMD's Model 645 

EMD's Model 710 

Truck Types

AAR Type A/B 

Blomberg Type A/M 



Related Companies/Designs

Davenport Locomotive Works 

Truck Types


Gensets/Green Goats 

Rail Diesel Car, RDCs 


Notable Events/Programs

Norfolk Southern's Heritage Program 

Streamliners At Spencer 

Union Pacific's Commemorative Series 

Two Sierra Railroad Baldwin S12s, led by #40, heads eastbound with a freight through Jamestown, California during a cold and overcast December day in 1964.

Diesels have come a long way from the early designs by EMC and Alco-GE-IR, with comfort cabs and electronic equipment the norm on new units now being built by Electro-Motive Diesel (now an independent company having been spun-off by EMD in 2005) and GE. However, when the diesel was first coming of age there were still several builders, many of whom were legendary steam locomotive manufacturers (such as Baldwin, Lima, and Alco) that began switching to diesel-electric development when the writing on the wall became apparent that steam's days were numbered. 

B&O GP9 #6533 is awaiting its next assignment as it sits at LeRoy, New York on March 15, 1981.

While a few of the steam locomotive manufacturers were marginally successful, most notably Alco, all of these once mighty companies would be gone before 1970 (mostly the result of management never able to truly see that steam was in its twilight and diesels were the future). While many of these companies no longer manufacture locomotives, their legacies will forever live on and many of both their steam and diesel locomotive models still survive, some even continuing to haul freight. Also, while diesels may have replaced the mighty steam locomotives, nothing can quite compare to seeing steam power at work! 

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