Chesapeake & Ohio class H-7
After various Mallets with the wheel arrangement 2-6-6-2, the C&O had the class H-7 built with the wheel arrangement 2-8-8-2. In 1923 and 1924, 25 H-7 were delivered by ALCO and in 1926 20 H-7a by Baldwin followed, which had a slightly higher adhesive weight. Since, unlike their predecessors, they worked with simple expansion, they were called “Simple Simons”.
By 1935 they received a boiler pressure of now 215 instead of 205 psi and thermic syphons. The 632 square foot firebox heating area now included 145 square feet from the combustion chamber and 165 from the thermic syphons. They could haul a 9,500 short tons freight train 113 miles in five hours.
They were replaced on the flatter lines by the class T-1 2-10-4 and on hilly lines by the 2-6-6-6 “Alleghenies”. 30 of the 45 locomotives were later leased to the Union Pacific. The Richmond, Fredericksburg & Potomac also bought some locomotives.
Technical data
General
- Built
- 1923-1926
- Manufacturers
- ALCO, Baldwin
- Wheel arrangement
- 2-8-8-2 (Mikado Mallet)
- Gauge
- 1,435 mm (Standard gauge)
Dimensions and weights
- Wheelbase
- 17.70 m
- Total wheelbase
- 31.92 m
- Service mass
- 257.4 t
- Adhesion mass
- 223.7 t
- Total mass
- 428.1 t
- Rigid wheelbase
- 4.80 m
- Axle load
- 29.6 t
- Water capacity
- 79,494 l
- Fuel capacity
- 22.7 t (coal)
Boiler
- Grate area
- 10.424 m²
- Firebox surface
- 58.715 m²
- Tube heating surface
- 552.588 m²
- Evaporative heating surface
- 611.303 m²
- Superheater surface
- 171.778 m²
- Total heating surface
- 783.1 m²
Power plant
- Driver diameter
- 1,448 mm
- Boiler pressure
- 14.8 bar
- Expansion type
- simple expansion
- Cylinders
- four, 584 x 813 mm
Power
- Power source
- steam
- Estimated power
- 3,169 kW (4,309 PS)
- Starting effort
- 482.8 kN
Calculated values
- Factor of adhesion
- 1 : 4.54
- Optimal speed
- 40 km/h
- Power-to-weight ratio
- 12.3 kW/t
- Heating Surface Equivalent
- 1,248.4 m²
- Cylinder volume/HSE
- 1 : 698.06
- Adhesive weight/Total
- 1 : 1.15
- Tractive force/Heating surface
- 1 : 12.88
- Grate area/Heating surface
- 1 : 75.12
- Firebox/Tube surface
- 1 : 9.41
- Total/Superheater
- 1 : 3.56