| Chesapeake and Ohio class M-1 | |
| Powertype: | Steam turbine electric |
| Builder: | Baldwin Locomotive Works |
| Serialnumber: | 73079–73081 |
| Buildmodel: | M-1 |
| Builddate: | 1947–1948 |
| Totalproduction: | 3 |
| Whytetype: | 4-6-2+4-6-2+0-4-0TE |
| Aarwheels: | 2-C1+2-C1-B |
| Uicclass: | (2'Co1)'(2'Co1Bo')' |
| Driverdiameter: | 400NaN0 |
| Length: | 154feet |
| Locoweight: | 8570001NaN1 |
| Locotenderweight: | 617t |
| Fueltype: | Coal |
| Fuelcap: | 29.25ST |
| Boilerpressure: | 3102NaN2 |
| Maxspeed: | 100mph |
| Poweroutput: | 6000-1NaN-1 (turbine) 4960-1NaN-1 (generators) |
| Operator: | Chesapeake and Ohio Railway |
| Fleetnumbers: | 500–502 |
| Nicknames: | Sacred Cow |
| Firstrundate: | 1947 |
| Lastrundate: | 1949 |
| Scrapdate: | 1950 |
| Disposition: | All scrapped |
The Chesapeake and Ohio class M-1 was a fleet of three steam turbine locomotives built by the Baldwin Locomotive Works for the Chesapeake and Ohio Railway in 1947–1948 for service on the Chessie streamliner. As diesel locomotives became more prevalent following World War II, the C&O was one of several railroads that were reluctant to abandon coal as a fuel source, and saw steam turbine technology as a possible alternative to diesel. At the time of its construction it was the longest single-unit locomotive in the world.
The design of the M-1 was a collaboration between the C&O, the Baldwin Locomotive Works and Westinghouse. The C&O possessed substantial coal-hauling revenue and was loath to abandon it as a fuel source. Further, C&O's engineering staff expressed concern that oil reserves would be exhausted within 25-30 years. The locomotive contained a single Westinghouse turbine which in turn drove four direct current (DC) generators, mounted in pairs. Each generator produced, and the four generators collectively turned eight traction motors.
Defying the usual convention, the M-1 was arranged with its boiler in the rear and the coal bunker in the front. The turbine-generator system meant that the M-1 contained no cylinders. The reduced number of moving parts meant that, in theory, the M1 required far less maintenance than a conventional steam locomotive. Its designers predicted that it could make a round trip between Washington and Cincinnati without servicing.
The locomotive's throttle included eleven settings, ranging from one (idling) to eleven (full speed). The locomotive's cruising speed was 70mph, at which point the throttle was on "seven." During a trial run with a reporter from Popular Mechanics aboard, a C&O engineer expressed his dissatisfaction with a local speed limit of 75mph, noting that he would "sure like to be able to pull it back to eleven!" Not including research and development, the three locomotives cost .
The C&O cancelled the Chessie in 1948, before it ran in revenue service, depriving the M-1s of their reason for existence. The M-1s themselves proved expensive to operate and mechanically unreliable. They spent their short careers operating between Clifton Forge and Charlottesville, Virginia. The locomotives were scrapped in 1950.