B&O No. 633 Switcher

General Motors, a company typically known for its automobiles, is also a big name in locomotive manufacturing. They began mass-producing diesel switchers in 1935. Switchers are designed for traversing rail yards, industrial parks, and other short distances. Often, they are used to assemble and disassemble trains. These lightweight locomotives offer crews better visibility, reversibility, and maneuverability compared to heavier engines designed for long hauls.  

In 1954, General Motors Electro-Motive Division (GM-EMD) unveiled the SW-900, a mid-sized, 900-horsepower diesel-electric switch locomotive known for its reliability and sturdiness. The B&O No. 633 was one of 29 SW-900s delivered to the B&O Railroad in the summer of 1955. Renumbered as B&O No. 9408 in 1957, the switcher spent the first 20 years of its career working in the Yard of Punxsutawney, PA. In 1975, the engine was leased to the Koppers chemical company of Green Spring, WV. The No. 9408 services Koppers’ railroad tie treatment facility until 1991, when the engine was returned to CSX Transportation (the successor of the B&O and Chessie System).  

The No. 9408 was sent to the B&O Railroad Museum in 1992, but not before participating in that year’s Cumberland Rail Festival. In late 1994, the SW-900 was refurbished with new footboards and handrails, and its original paint scheme, livery, and number were restored. The No. 633 is still operational, and it is used to move equipment around the museum from time to time.  

GM-EMD produced 260 SW-900 engines between 1954 and 1965. By the mid-1980s, these mid-sized units were largely replaced by the GP40, a four-axle, 3,000-horsepower “general purpose” road switcher designed for both industrial yard and branch line services. GM-EMD continued to evolve the GP series until it was discontinued in 2001. General Motors eventually sold its Electro-Motive Division in 2005.