The C&O Power authors tell us that the K-2s and K-3s (Locobase 482) were, "for nearly 20 years" the "mainstay of C&O gradient power." Their design stemmed from a realization that the 1911 K-1 Mikes (Locobase 480) were "technologically outdated" in their cylinder volume, boiler pressure, and driver diameter. The K-2s shown here were delivered with trailing truck boosters, shorter strokes; the authors note that these "light" Mikados actually outweighed the K-3 Heavies by several thousand pounds. Both classes used the same superheater layouts and both used 14" (356 mm) piston valves versus the 16" valve installed in the K-1s.
Cylinder horsepower calculated to be 2,824. Elesco or Worthington feedwater heaters and starting boosters.
All remained in service until dieselization in 1952.