Class H-7 (Locobase 312)
Data from C&O 9 - 1936 and C&O 12 - 1946 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection. For the Baldwins, see DeGolyer, Vol 75, pp. 93+. (Thanks to Chris Hohl for his 28 November 2012 email that pointed out the gap in numbering by the C&O.) First 25 H-7 built by Alco as works numbers 64952-64976 in December 1923. The first, 1100 arrived in December 1923, 1101-1103 in January, 1104-1110 in February, and 1111-1124 in March. When the C&O renumbered the class in 1926, for some reason the railroad replaced 1124 with 1540 and 1100 with 1541; the rest of the class received 1542-1564 in order.
The latter 20 (numbered 1570-1589 from the start) came from Baldwin in 1926 (works numbers 58922, 58950, 58964-58966 in January, 59052-59058 in March, 59110-59113 in April, 59174-59177 in May).
Known as "Simple Simons" or "Simons" (according to C&O Power) because they operated as simple-expansion articulateds, unlike the earlier compound Mallets. Firebox had combustion chamber that added 145 sq ft (13.45 sq m) to direct heating surface area and the boiler had an Elesco K-54 feed water heater. When delivered, boilers were pressed at 205 psi. All four cylinders were supplied through 12" (305 mm) piston valves.
The Baldwin H-7as were credited with slightly higher weight on drivers, larger heating surface (6,580 sq ft). Cylinder horsepower for all was 4,092 hp.
By 1935, all of the H-7s were fitted with several thermic syphons that contributed a total of 165 sq ft (15.3 sq m) to the direct heating surface area. The result is shown in the specifications.
Alexander (American Locomotives, 1950) notes that H7 pulled 9,500-ton trains over 113-mile run from Russell, Kentucky to Columbus, Ohio in 5 hours. Averaged 4,400 miles per month until displaced by the 2-10-4s in Ohio and the 2-6-6-6 Alleghenies in the rest of the territory. 30 of the fifty were later leased to the Union Pacific. By then the fireboxes had been fitted with 167 sq ft of thermic syphon as shown in the specs.