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The reference for locomotives and railcars

Chesapeake & Ohio class H-7

United States 1923 45 produced
Former C&O No. 1123 as Richmond, Fredericksburg & Potomac No. 2 collection Taylor Rush

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
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