The ALCO RSD-15 was a heavy-duty six-axle (C-C) diesel-electric road switcher locomotive built by the American Locomotive Company (ALCO) between 1959 and 1960. A total of 75 units were produced during this short production run. Known for its powerful ALCO 251B V12 prime mover generating 1,500 horsepower (1,119 kW), the RSD-15 was designed for applications requiring high tractive effort, such as heavy drag freight service and helper operations on steep grades.
Development and Design
The RSD-15 represented ALCO's continued development of its highly successful road switcher line, following models like the RS-11 and RSD-12. Unlike its four-axle (B-B) and four-axle A1A-A1A predecessors, the RSD-15 utilized two three-axle trucks in a C-C wheel arrangement. This configuration provided better weight distribution, increased adhesion, and superior tractive effort, making it ideal for the demanding tasks of heavy freight hauling and switching on challenging terrain.A distinctive feature of many RSD-15 units was their elongated, low-profile hood with a high short hood. This characteristic profile led to the locomotive earning the popular nickname "Alligator" among railroad enthusiasts and crews, due to its resemblance to the reptile. While most units were built with the high short hood, some later units (notably for the Erie Lackawanna) were delivered with a lower short hood for improved forward visibility.
Technical Specifications
- Type: Diesel-electric road switcher
- Builder: American Locomotive Company (ALCO)
- Model: RSD-15
- Production: 1959–1960
- Total Built: 75 units
- Configuration: C-C
- Gauge: 4 ft 8+1⁄2 in (1,435 mm) standard gauge
- Engine: ALCO 251B V12 prime mover
- Power Output: 1,500 hp (1,119 kW)
- Traction Motors: General Electric
- Weight: Approximately 370,000 lb (167,829 kg)
- Length: Approximately 60 ft 10 in (18.54 m)
- Fuel Capacity: Typically 1,600 US gallons (6,100 L)
Operational History
The ALCO RSD-15 found service on several prominent North American railroads, where their robust power and high tractive effort were put to good use. Key original purchasers included:- Southern Pacific (SP): A significant buyer, utilizing them for heavy freight on mountain grades.
- Pennsylvania Railroad (PRR): Employed them in various freight and helper services.
- Atchison, Topeka and Santa Fe Railway (ATSF): Used them primarily in heavy switching and road service.
- Duluth, Missabe and Iron Range Railway (DM&IR): Valued them for hauling heavy iron ore trains.
- Erie Lackawanna Railroad (EL): Some units featured a low short hood design for improved visibility.
- Northern Pacific Railway (NP): Also operated a fleet of these locomotives.
While powerful, ALCO locomotives, including the RSD-15, sometimes developed a reputation for being maintenance-intensive compared to their contemporaries from General Motors Electro-Motive Division (EMD). Despite this, many RSD-15s served their original owners for many years, often being rebuilt or re-engined later in their lives.
Nicknames
The ALCO RSD-15 is widely recognized by its distinctive nickname, the "Alligator," primarily due to its long, low body profile and, on most units, the prominent high short hood. This unique appearance made it easily identifiable among other diesel locomotives of its era.Preservation
At least one ALCO RSD-15 unit has been preserved:- DM&IR 32: This locomotive, originally built for the Duluth, Missabe and Iron Range Railway, is preserved at the Lake Superior Railroad Museum in Duluth, Minnesota, where it is a popular exhibit.