The ALCO RSC-2 was a

diesel-electric locomotive A diesel locomotive is a type of railway locomotive in which the power source is a diesel engine. Several types of diesel locomotives have been developed, differing mainly in the means by which mechanical power is conveyed to the driving whee ...

that rode on three-axle

trucks A truck or lorry is a motor vehicle designed to transport freight, 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 ...

, having an

A1A-A1A The AAR wheel arrangement system is a method of classifying locomotive A locomotive is a rail transport, rail vehicle that provides the motive power for a train. Traditionally, locomotives pulled trains from the front. However, Push–pu ...

wheel arrangement. 91 locomotives were produced — Used in much the same manner as its four-axle counterpart, the

ALCO RS-2 The ALCO RS-2 is a AAR wheel arrangement#B-B, B-B diesel-electric locomotive built by the American Locomotive Company (ALCO) from 1946 to 1950. ALCO introduced the model after World War II as an improvement on the ALCO RS-1. Between 1946 and 19 ...

, though the wheel arrangement lowered the

axle load The axle load of a wheeled vehicle is the total weight bearing on the roadway for all wheels connected to a given axle. Axle load is an important design consideration in the engineering of roadways and railways, as both are designed to tolerate a m ...

for operation on light rail such as are found on

branch line A branch line is a secondary railway line which branches off a more important through route, usually a main line. A very short branch line may be called a spur line. Branch lines may serve one or more industries, or a city or town not located ...

s. The

Milwaukee Road The Chicago, Milwaukee, St. Paul and Pacific Railroad (CMStP&P), better known as the Milwaukee Road , was a Class I railroad that operated in the Midwestern United States, Midwest and Pacific Northwest, Northwest of the United States from 1847 ...

was the first railroad to take delivery of the RSC-2, initially assigning them to their Valley Division (headquartered near

Wausau, Wisconsin Wausau ( ) is a city in Marathon County, Wisconsin, United States, and its county seat. It is located along the Wisconsin River and had a population of 39,994 as of the 2020 United States census, 2020 census. It is the core city of the Wausau ...

) in November 1946. This was done in order to study the effects of an all-diesel roster (i.e. no steam locomotives available as a backup). The experiment was deemed a success and soon all steam locomotives were gone from the Valley Division. RSC-2s would faithfully serve the Milwaukee Road for many years, until being replaced in turn by the

EMD SDL39 The EMD SDL39 is a model of 6-axle diesel-electric locomotive built by General Motors Electro-Motive Division between March 1969 and November 1972. Power was provided by the EMD 645E3 12-cylinder engine as used in the EMD GP39 which generated 2, ...

. ALCO also exported these units to the state railway of

Portugal Portugal, officially the Portuguese Republic, is a country on the Iberian Peninsula in Southwestern Europe. Featuring Cabo da Roca, the westernmost point in continental Europe, Portugal borders Spain to its north and east, with which it share ...

, where Portuguese Railways (CP) designated them Série 1500. These locomotives were built for the Iberian track gauge of (). The last units in Portugal served in regular passenger service into the first decade of the 21st century. Of these, five are still running today, 70 years after their arrival (one is a museum locomotive, while the other four are owned by track maintenance companies). Five units were exported to the Algerian National Railways where they were used in passenger train service.

Original buyers

References

* {{ALCO diesels A1A-A1A locomotives RSC-2 Diesel–electric locomotives of the United States Railway locomotives introduced in 1946 Standard-gauge locomotives of the United States Iberian-gauge locomotives Standard-gauge locomotives of Algeria Diesel–electric locomotives of Portugal Diesel–electric locomotives of Algeria Milwaukee Road locomotives Soo Line locomotives Union Pacific Railroad locomotives