Built in several batches: 1600-1609 in 1941 (works numbers 7820-7823 in December 1941, 7824-7829 in January 1942), 1610-1619 in 1942 (works numbers 7883-7892 in September), and 1620-1644 in 1944 (works number 8613-8622 in July, 8799-8813 in October-November).
Firebox had three syphons and arch tubes combining for 162 sq ft of heating surface as well as a huge combustion chamber. Each cylinder was served by a 12" (306 mm) piston valve. All engine and tender axles turned inside Timken roller bearings. A Worthington Type 6 1/2 SA feed water heater raised the temperature of incoming boiler water.
H-8s could operate 11,500-ton coal trains at speeds up to 45 mph (72.5 km/h). Probably the heaviest twelve-axle locomotives ever built, with certainly the highest axle load ever put on rails. Average axle load was 84,650 lb (38,397 kg) and the first driving axle bore 86,700 lb (39,327 kg).
C&O Power gives higher weight on drivers (507,900 lb for the first batch, 504,010 lb for the 1948 engines), and heavier engine weights (771,300 lb and 751,830 lb, respectively.) The answer is that Cyclopedia weights were as designed, which specified 471,000 lb on the drivers, 724,500 for the engine. C&O Power weights came from C&O drawings.
Bob Quehl (EMail:email@example.com) from Pittsburgh, PA offered considerable detail on the difference as well as other information (http://www.worldrailfans.org/Forum/1998/Jan/2281650.shtmlon Feb 4 2000, 4:06) " In the December 1998 issue of Trains Magazine there is a very interesting article that suggests the first 10 H-8s delivered in December 1941 to January 1942 weighed actually weighed in the area of 775,330 lbs in "working order". This was just the engine weight including water in the boiler, 12,000 lbs of sand in the domes an a two man engine crew. This is interesting because the specifications for the order between the C&O and Lima called for a weight of 726,000 lbs."
Quehl implies that it was the Virginian's order of eight in 1945 that finally exposed the disparity. "One engineer at Lima gave the H-8's weight as high as 778,200 lbs. For the engine and tender combined weight I have seen several references in other sources around 1,200,000 lbs."
There are many (including Eugene Huddleston and Thomas Dixon, Jr in their book Allegheny: Lima's Finest) who contend that C & O's oversight of the design by its Advisory Mechanical Committee contributed mightily to the problem. One example cited is four different changes to the design of the connecting rods, each of which made them heavier. According to Huddleston and Dixon, Lima later paid the C & O a $3 million penalty for missing the weight targets by so wide a margin.
But did the C & O get what it paid for, whatever the cost in weight? It appears so, although the coal traffic they served didn't require the Challenger-like 67" drivers and massive tenders that this class deployed. To cope with an adverse grade of about 0.6%, the C & O would marshal 100 loaded coal cars, place one H-8 at the front and one at the rear and put the whole thing in motion. Once the train crested the summit, the pusher would drop off and the front H-8 would manage the train by itself.
23 were equipped for passenger operation, but if they were so used, it was to pull troop trains.
See Locobase 304 for comments on the serious weight miscalculation in the original H-8 design. When adding to the stud, the C & O adopted the smaller design sold to the Virginian in 1945 (Locobase 421). The big change from the 1941 Alleghenies was a 21% cut in the number of flues for the Type E superheater, which was only partially offset by an increase in the 2 1/4" tubes of 10.
Firebox had three syphons and arch tubes combining for 162 sq ft of heating surface as well as a huge combustion chamber. Could operate 11,500-ton coal trains at speeds up to 45 mph.
|Specifications by Steve Llanso of Sweat House Media|
|Class||H-8 - 1600||H-8 - 1644|
|Railroad||Chesapeake & Ohio (C & O)||Chesapeake & Ohio (C & O)|
|Locomotive Length and Weight|
|Ratio of driving wheelbase to overall engine wheebase||0.19||0.19|
|Overall Wheelbase (engine & tender)||112.92'||112.92'|
|Axle Loading (Maximum Weight per Axle)||86700 lbs||85480 lbs|
|Weight on Drivers||507900 lbs||504010 lbs|
|Engine Weight||771300 lbs||751830 lbs|
|Tender Light Weight||428100 lbs||431710 lbs|
|Total Engine and Tender Weight||1199400 lbs||1183540 lbs|
|Tender Water Capacity||25000 gals||25000 gals|
|Tender Fuel Capacity (oil/coal)||25 tons||25 tons|
|Minimum weight of rail (calculated)||141 lb/yard||140 lb/yard|
|Geometry Relating to Tractive Effort|
|Boiler Pressure||260 psi||260 psi|
|Cylinders (dia x stroke)||22.5" x 33"||22.5" x 33"|
|Tractive Effort||110211 lbs||110211 lbs|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||4.61||4.57|
|Firebox Area||762 sq. ft||762 sq. ft|
|Grate Area||135.20 sq. ft||135 sq. ft|
|Evaporative Heating Surface||7240 sq. ft||6795 sq. ft|
|Superheating Surface||3186 sq. ft||2922 sq. ft|
|Combined Heating Surface||10426 sq. ft||9717 sq. ft|
|Evaporative Heating Surface/Cylinder Volume||238.37||223.72|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||35152||35100|
|Same as above plus superheater percentage||46049||45630|
|Same as above but substitute firebox area for grate area||259537||257556|
The Virginian 2-6-6-6s came it at about 754,000 lbs, still overweight, but less so than the C&O engines. The final 15 C&O engines came in at 757,830 lbs. Lima ended up paying the C&O a penalty, perhaps as much as $3,000,000 because of this overweight problem.
No matter the actual locomotive weight, this weight makes the Allegheny the
heaviest of any reciprocating steam locomotive built in North America, even
heavier than the Big Boy.