The R-2s (2505-2509; delivered in 1937) had slightly fewer tubes for a total EHS of 5,429 sq ft, a cleaner-looking Walschaerts valve motion, single crosshead guides, and Elesco feedwater heaters replaced by Worthingtons, but otherwise varied little from the earlier R-1s. Data in specs from the 1947 SAL locomotive diagram supplied in May 2005 by Allen Stanley from his extensive collection.
These engines later (1947) went on to the B&O as KB-1 and KB-1a 7700-7709, where the slip joints in the piping to the front engine unit (which leaked frequently) were replaced by ball joints. They were slippery on grades and not as well liked as the Big Sixes (2-10-2), although a later relocation of the air pumps to the pilot on one engine reduced the slipping.
| Specifications | |
|---|---|
| Class | R-1/R-2 |
| Locobase ID | 302 |
| Railroad | Seaboard Air Line (SAL) |
| Whyte | 2-6-6-4 |
| Road Numbers | 2500-2509 |
| Gauge | Std |
| Builder | Baldwin |
| Year | 1935 |
| Valve Gear | Baker or Walschaert |
| Locomotive Length and Weight | |
| Driver Wheelbase | 12' |
| Engine Wheelbase | 67.42' |
| Ratio of driving wheelbase to overall engine wheebase | 0.18 |
| Overall Wheelbase (engine & tender) | 97.75' |
| Axle Loading (Maximum Weight per Axle) | 55000 lbs |
| Weight on Drivers | 330000 lbs |
| Engine Weight | 480000 lbs |
| Tender Light Weight | 310200 lbs |
| Total Engine and Tender Weight | 790200 lbs |
| Tender Water Capacity | 16000 gals |
| Tender Fuel Capacity (oil/coal) | 24 tons |
| Minimum weight per yard of rail on which locomotive could run | 91.67 lb rail |
| Geometry Relating to Tractive Effort | |
| Driver Diameter | 69" |
| Boiler Pressure | 230 psi |
| Cylinders (dia x stroke) | 22" x 30" (4) |
| Tractive Effort | 82280 lbs |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 4.01 |
| Heating Ability | |
| Firebox Area | 516 sq. ft |
| Grate Area | 96.30 sq. ft |
| Evaporative Heating Surface | 5513 |
| Superheating Surface | 2397 |
| Combined Heating Surface | 7910 |
| Evaporative Heating Surface/Cylinder Volume | 208.84 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 22149 |
| Same as above plus superheater percentage | 28860.90 |
| Same as above but substitute firebox area for grate area | 154644.09 |
| Power L1 | 29724.32 |
| Power MT | 1191.47 |
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