The

Pennsylvania Railroad The Pennsylvania Railroad (reporting mark PRR), legal name The Pennsylvania Railroad Company also known as the "Pennsy", was an American Class I railroad that was established in 1846 and headquartered in Philadelphia, Pennsylvania. It was named ...

's class DD2

electric locomotive An electric locomotive is a locomotive powered by electricity from overhead lines, a third rail or on-board energy storage such as a battery or a supercapacitor. Locomotives with on-board fuelled prime movers, such as diesel engines or gas ...

was a single prototype locomotive never placed into series production. It was intended as an improved and simplified

GG1 The Pennsylvania Railroad GG1 is a class of streamlined electric locomotives built for the Pennsylvania Railroad (PRR), in the northeastern United States. The class was known for its striking art deco shell, its ability to pull trains at up to 10 ...

for use on the planned, but never built, extension of the PRR's electrification west of

Harrisburg, Pennsylvania Harrisburg is the capital city of the Commonwealth of Pennsylvania, United States, and the county seat of Dauphin County. With a population of 50,135 as of the 2021 census, Harrisburg is the 9th largest city and 15th largest municipality in Pe ...

. The one locomotive produced was numbered #5800 and used in regular Baltimore tunnel helper service until it was scrapped in September 1962.

Design, construction and testing

On May 21, 1937, a meeting was held in Philadelphia to outline the design of a new electric freight locomotive. The meeting was attended by the PRR and Baldwin, as well as electrical suppliers

General Electric General Electric Company (GE) is an American multinational conglomerate founded in 1892, and incorporated in New York state and headquartered in Boston. The company operated in sectors including healthcare, aviation, power, renewable energ ...

and Westinghouse, and the transportation engineering firm Gibbs & Hill, who were consultants on the proposal to extend electrification to

Pittsburgh Pittsburgh ( ) is a city in the Commonwealth (U.S. state), Commonwealth of Pennsylvania, United States, and the county seat of Allegheny County, Pennsylvania, Allegheny County. It is the most populous city in both Allegheny County and Wester ...

. The locomotive being designed was what became the DD2.

Technical details

Although the design specified either passenger gearing or freight gearing, the prototype was only ever used with freight gearing. Its

wheel arrangement In rail transport, a wheel arrangement or wheel configuration is a system of classifying the way in which wheels are distributed under a locomotive. Several notations exist to describe the wheel assemblies of a locomotive by type, position, and c ...

was 4-4-0+0-4-4 in the

Whyte notation Whyte notation is a classification method for steam locomotives, and some internal combustion locomotives and electric locomotives, by wheel arrangement. It was devised by Frederick Methvan Whyte, and came into use in the early twentieth ce ...

, or 2-B+B-2 in the AAR's system. It had two frames, hinged together in the middle, with the driving wheels and motors mounted directly to each frame, two pairs per side. A swinging four-wheeled, unpowered

truck A truck or lorry is a motor vehicle designed to transport cargo, carry specialized payloads, or perform other utilitarian work. Trucks vary greatly in size, power, and configuration, but the vast majority feature body-on-frame construction ...

was mounted at the outer end of each frame. The bodywork, mounted above, swivelled on mounts on each of the two main frames. This was an identical layout to the better-known

electric locomotives, but with four driven axles instead of six. Each driven wheel had two

electric motor An electric motor is an Electric machine, electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a Electromagneti ...

s, each rated at , giving a total rating of for the locomotive. Although it had fewer driven wheels than the GG1, the total power output was slightly greater, thanks to newer and more powerful motors. Weight on the driven wheels was approximately ., (simple drawing and specifications, for general reference by railroad staff). compared to the GG1's , meaning that in similar conditions of adhesion the GG1 was slightly at an advantage in terms of applying power to the rail, but the difference was not great. Styling was also similar to the GG1's.

References

{{PRR locomotives 11 kV AC locomotives DD2 2-Bo-Bo-2 locomotives Experimental locomotives Individual locomotives of the United States Electric locomotives of the United States Scrapped locomotives Unique locomotives Standard gauge locomotives of the United States Railway locomotives introduced in 1938 Freight locomotives Streamlined electric locomotives