Firebox had combustion chamber that contributed 155 sq ft to direct heating surface, the boiler had exhaust steam injectors, and steam was distributed through 14" diameter piston valves.
The first four were built by Baldwin (works #58480-58481 in June 1925 and 58528, 58542 in July) and the last ten by Great Northern.
Boiler fitted with exhaust steam injector. The firebox heating surface included 178 sq ft from the combustion chamber and a surprisingly high 78 sq ft in arch tubes.
The Great Northern's essay in simple articulateds produced this immense specimen that reflected the influence of the superpower revolution of the late 1920s. Note the size of the boiler and the superheat surface. Compared to the R-1s by Baldwin, these engines had 10% more EHS, 85.4% more SHS, 8.8% lower BDF, and a 14.5% increase in indicated TE. Notice too that these engines grossed out at 1,003,530 pounds with loaded tender.
| Specifications | ||
|---|---|---|
| Class | R-1s | R-2 |
| Locobase ID | 320 | 321 |
| Railroad | Great Northern (GN) | Great Northern (GN) |
| Whyte | 2-8-8-2 | 2-8-8-2 |
| Road Numbers | 2030-2043 | 2044-2059 |
| Gauge | Std | Std |
| Builder | several | GNR |
| Year | 1925 | 1929 |
| Valve Gear | Walschaert | |
| Locomotive Length and Weight | ||
| Driver Wheelbase | 16.50' | 16.50' |
| Engine Wheelbase | 58.17' | 70.60' |
| Ratio of driving wheelbase to overall engine wheebase | 0.28 | 0.23 |
| Overall Wheelbase (engine & tender) | 96.29' | |
| Axle Loading (Maximum Weight per Axle) | 67500 lbs | 68000 lbs |
| Weight on Drivers | 532800 lbs | 544000 lbs |
| Engine Weight | 594940 lbs | 630750 lbs |
| Tender Light Weight | 321560 lbs | 372780 lbs |
| Total Engine and Tender Weight | 916500 lbs | 1003530 lbs |
| Tender Water Capacity | 16000 gals | 22000 gals |
| Tender Fuel Capacity (oil/coal) | 5800 gals | 5800 gals |
| Minimum weight per yard of rail on which locomotive could run | 111 lb rail | 113 lb rail |
| Geometry Relating to Tractive Effort | ||
| Driver Diameter | 63" | 63" |
| Boiler Pressure | 210 psi | 240 psi |
| Cylinders (dia x stroke) | 28" x 32" (4) | 28" x 32" (4) |
| Tractive Effort | 142165 lbs | 162475 lbs |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 3.75 | 3.35 |
| Heating Ability | ||
| Firebox Area | 431 sq. ft | 559 sq. ft |
| Grate Area | 108 sq. ft | 126 sq. ft |
| Evaporative Heating Surface | 7125 | 7947 |
| Superheating Surface | 1920 | 3515 |
| Combined Heating Surface | 9045 | 11462 |
| Evaporative Heating Surface/Cylinder Volume | 156.21 | 174.23 |
| Computations Relating to Power Output (More Information) | ||
| Robert LeMassena's Power Computation | 22680 | 30240 |
| Same as above plus superheater percentage | 27443 | 39614 |
| Same as above but substitute firebox area for grate area | 109517 | 175750 |
| Power L1 | 12840 | 23413 |
| Power MT | 425.03 | 759.07 |
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