In addition to a high-pressure boiler, an A had a cast-steel frame and roller bearings on virtually all surfaces. The firebox had 57 sq ft of arch tubes, but no circulators or syphons. The last five of the type had roller bearings in the side and main rods, the only articulateds to take such friction-reducing measures.
Robert Le Massena (Trains, November 1991) says that this group had several traction-boosting differences that weren't publicized, such an increase in boiler pressure to 315 psi, drivers shrunk by half an inch to 69 1/2", and cylinders bored out to 24 1/2". The smokebox was insulated, valve gear pivoted on needle bearings, circulating tubes improved heating in the firebox. Total weight on the drivers increased 42,000 lb to 475,000 lb. Cutoff remained at 75%.
Max consumption rates per hour were 7 tons of coal burned and 116,055 lb of water evaporated.
Engine designs like these offer the best support for the contention that steam could equal diesel in cost-effective rail transport, but no other railroads could offer the combination of home-grown talent, facilities, and relatively cheap coal possessed by the N&W. Ultimately, even the N&W had to relent. All the As were retired in 1958-1959.
| Specifications | |
|---|---|
| Class | A |
| Locobase ID | 300 |
| Railroad | Norfolk & Western |
| Whyte | 2-6-6-4 |
| Road Numbers | 1200-1242 |
| Gauge | Std |
| Builder | N & W |
| Year | 1936 |
| Valve Gear | Baker |
| Locomotive Length and Weight | |
| Driver Wheelbase | 12.33' |
| Engine Wheelbase | 60.39' |
| Ratio of driving wheelbase to overall engine wheebase | 0.20 |
| Overall Wheelbase (engine & tender) | 108.27' |
| Axle Loading (Maximum Weight per Axle) | 72000 lbs |
| Weight on Drivers | 433350 lbs |
| Engine Weight | 573000 lbs |
| Tender Light Weight | 378600 lbs |
| Total Engine and Tender Weight | 951600 lbs |
| Tender Water Capacity | 22000 gals |
| Tender Fuel Capacity (oil/coal) | 26 tons |
| Minimum weight per yard of rail on which locomotive could run | 120.38 lb rail |
| Geometry Relating to Tractive Effort | |
| Driver Diameter | 70" |
| Boiler Pressure | 300 psi |
| Cylinders (dia x stroke) | 24" x 30" (4) |
| Tractive Effort | 125897 lbs |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 3.44 |
| Heating Ability | |
| Firebox Area | 587 sq. ft |
| Grate Area | 122 sq. ft |
| Evaporative Heating Surface | 6639 |
| Superheating Surface | 2703 |
| Combined Heating Surface | 9342 |
| Evaporative Heating Surface/Cylinder Volume | 211.33 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 36600 |
| Same as above plus superheater percentage | 47189.79 |
| Same as above but substitute firebox area for grate area | 227052.50 |
| Power L1 | 37768.58 |
| Power MT | 1152.86 |
| This page last modified: . | [Contact] | All material © 1999-2008 SteamLocomotive.com |
