4 sub-classes:
S (700-714) built in 1934
S-1 (715-739) built in 1942
S-2 (740-769) built in 1944. Roller bearings on the driving axles.
S-3 (770-779) built in 1949
All very successful. S-3 weight on drivers 266,000 lb, engine weight 444,300, Factor of adhesion slightly higher.
See Railfan & Railroad, March 1994, for a long article by Rich Melvin in which he recounts excursion runs with 765 that demonstrate just how powerful this class was. Melvin underscores the slogan coined by Lima's Will Woodard to explain the SuperPower concept: "Horsepower at Speed." The article contains an excellent analysis of the strengths of a steam horsepower curve (there's more the faster you go) and diesel horsepower (there's plenty at the low end, but the system reaches its upper limit at a speed well below an equivalent steam engine).
| Specifications | |
|---|---|
| Class | S |
| Locobase ID | 52 |
| Railroad | Nickel Plate |
| Whyte | 2-8-4 |
| Road Numbers | 700-779 |
| Gauge | Std |
| Builder | Lima |
| Year | 1934 |
| Valve Gear | |
| Locomotive Length and Weight | |
| Driver Wheelbase | 18.20' |
| Engine Wheelbase | 42' |
| Ratio of driving wheelbase to overall engine wheebase | 0.43 |
| Overall Wheelbase (engine & tender) | 87.70' |
| Axle Loading (Maximum Weight per Axle) | |
| Weight on Drivers | 254000 lbs |
| Engine Weight | 421000 lbs |
| Tender Light Weight | 283400 lbs |
| Total Engine and Tender Weight | 704400 lbs |
| Tender Water Capacity | 22000 gals |
| Tender Fuel Capacity (oil/coal) | 22 tons |
| Minimum weight per yard of rail on which locomotive could run | 105.83 lb rail |
| Geometry Relating to Tractive Effort | |
| Driver Diameter | 69" |
| Boiler Pressure | 245 psi |
| Cylinders (dia x stroke) | 25" x 34" |
| Tractive Effort | 64135 lbs |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 3.96 |
| Heating Ability | |
| Firebox Area | 461 sq. ft |
| Grate Area | 90.30 sq. ft |
| Evaporative Heating Surface | 4818 |
| Superheating Surface | 1992 |
| Combined Heating Surface | 6810 |
| Evaporative Heating Surface/Cylinder Volume | 249.42 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 22123.50 |
| Same as above plus superheater percentage | 28594.87 |
| Same as above but substitute firebox area for grate area | 145982.66 |
| Power L1 | 36538.77 |
| Power MT | 1268.57 |
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