C&O Steam Locomotives:
In the beginning C&O used the 4-4-0 and 4-6-0 types that were mid-19th Century Standards, and in the 1880s began using the 2-8-0 type for much of its heavier freight. These types became larger and more powerful over time, and in 1910 the road purchased its first Compound Articulated locomotive (Mallet), a type for which it would later become well known.
The 4-4-2 and 4-6-2 Pacific Type had come into the passenger stable in 1902. In 1911 the huge 4-8-2 Mountain type topped the passenger roster, while the Pacific type continued to be modernized and developed until the fabulous F-19 class Pacifics of 1926 brought that wheel arrangement to its apogee on the C&O. The Mountain was eventually supplemented by the 4-8-4 Greenbrier type in 1935 onward. The heaviest 4-6-4 Hudsons of all time were placed in service during and after WWII.
For freight the 2-6-6-2s held sway on the main line and as each new class of these locomotives became heavier the older ones were relegated to use on mine runs and branch lines in West Virginia and Kentucky coal fields. Eventually all compound Articulateds were put into the later service as heavier straight coupled locomotives and simple Articulateds became the norm for mainline trains.
The massive H-7 2-8-8-2 simple articulated of 1923 and 1926 raised the capacity of single locomotives markedly. In 1930 the monstrous Superpower dream 2-10-4s arrived and lasted to the end of steam. During WWII C&O began aquiring 2-8-4 types of the most modern design.
The ultimate locomotive on the C&O and one for which it will always be remembered is the 2-6-6-6 simple articulated H-8 class Allegheny type. It is the only steam locomotive to handle a 6-wheel trailing truck (because of its cavernous fire box), and generated the highest instantaneous and sustained drawbar horsepower at speed of any steam locomotive. It was also the heaviest locomotive ever built. Some say that if the C&O had used this wonderful machine to its fullest potential it could have routinely outperformed even the diesels. Sixty of these giants were built between 1941 and 1948. Two remain, Number 1601 at the Henry Ford Museum in Dearborn, MI and Number 1604 at the B&O Railroad Museum in Baltimore, MD.
C&O also had 0-6-0, 0-8-0, and even 0-10-0 switching locomotives, the later two types to handle large cuts of heavily loaded coal cars at various terminals.
At one time in the late 1940s C&O had 13 different wheel arrangements of steam locomotives in operation. Only the Sante Fe Railway had more wheel arrangements in service at any one time.
The standard reference for C&O Steam Locomotives is C&O Power by Gene Huddleston, Phil Shuster, and Alvin Staufer. At this writing it has been out of print for several years and usually commands a large price. The C&OHS runs steam locomotive articles periodically in its monthly magazine.
C&O Diesel Locomotives:
C&O was reluctant to dieselize because its management felt that since the principal commodity it hauled was coal, it should retain coal-fired motive power. For that reason, there was no early experimentation with diesel-electric motive power as on many other railroads. Howerver, seeing the obvious economics of diesels, management tried to find a middle ground solution. The result was the huge M-1 class Steam-Turbine-Electrics of 1947-48. They incorporated the efficiency of electric drive, but instead of a diesel prime mover, standard steam locomotive power and steam turbine supplied the power for the electric generator. The M-1 class steam turbines were used briefly, but the maintenance required for its standard steam generating plant could not match the lower mainttenance costs of the new diesels. More money and time was spent on research of a coal-gas turbine, without success.
Finally, in 1949 the inevitable happened and C&O bought its first diesels (Pere Marquette when it was an independent subsidary had acquired a diesel switcher in 1939, and E7 passenger diesels in 1946.) The news releases said that these would be used only as a bridge until an efficient coal-consuming turbine could be developed.
But by 1952 C&O had dieselized all its lines east of Clifton Forge and west of Cincinnati, and by 1954 steam was down to about 12% of C&O's total active motive power. It would have been gone shortly except for a large increase in traffic in 1955-56 resulting in previously retired steamers being pulled out for one last hurrah until more diesels could arrive. By October 1956 C&O was totally dieselized.
C&O used a wide variety of diesels at the outset, but settled on Electro-Motive Division of General Motors (EMD) as its principal builder, acquiring hundreds of GP7 and GP9 diesels to handle most of its work. The Second Generation of diesels began to arrive in 1963 with the GP30s from EMD, and in 1964 the U25Bs from General Electric. Over the next decade GE locomotives gained a larger foothold on the C&O, and by Chessie System days, equaled the EMD units.
Most of the locomotives bought under C&O/Chessie System have now been supplanted by the huge modern 4,000 and 6,000 horsepower units from GE and EMD used by CSX.