Firebox had 4 thermic syphons that totalled 155 sq ft . Note that these 10 locomotives, built 15 years after the earlier R-67-B group, have much less superheating area, outdated tube and flue arrangement. Wartime restrictions on high-temperature alloys probably had something to do with that retrograde. In fact, they strongly resemble the Delaware & Hudson K-62s built at the same time by the same builder. Among more modern features these engines showed were roller bearings on all axles and Boxpok drivers. These engines were oil-fired.
Firebox had 150 sq ft of thermic syphons. According to Drury (1993), this design's size and weight limited their operation to the Chicago-Des Moines corridor, the Chicago-Dalhart, Texas line, and the segment between Herington, Kan and El Reno, Okla. Later bridge-strengthening allowed these heavyweights to pull freights and passenger trains to Denver, Fort Worth, Tucumcari, and Minneapolis. Ten of this large stud of Northerns (the largest on a North American road) received a larger tender, roller bearings, and thicker driver tires.
| Specifications | ||
|---|---|---|
| Class | R-67 | R-67-B |
| Locobase ID | 251 | 250 |
| Railroad | Rock Island (CRI & P) | Rock Island (CRI & P) |
| Whyte | 4-8-4 | 4-8-4 |
| Road Numbers | 5100-5119 | 5000-5064 |
| Gauge | Std | Std |
| Builder | Alco-Schenectady | Alco-Schenectady |
| Year | 1944 | 1929 |
| Valve Gear | Walschaert | Baker |
| Locomotive Length and Weight | ||
| Driver Wheelbase | 19.75' | 19.25' |
| Engine Wheelbase | 47.08' | 45.58' |
| Ratio of driving wheelbase to overall engine wheebase | 0.42 | 0.42 |
| Overall Wheelbase (engine & tender) | 95.92' | 88' |
| Axle Loading (Maximum Weight per Axle) | ||
| Weight on Drivers | 280000 lbs | 265500 lbs |
| Engine Weight | 467000 lbs | 434000 lbs |
| Tender Light Weight | 370500 lbs | 304300 lbs |
| Total Engine and Tender Weight | 837500 lbs | 738300 lbs |
| Tender Water Capacity | 21500 gals | 15000 gals |
| Tender Fuel Capacity (oil/coal) | 5500 gals | 20 tons |
| Minimum weight per yard of rail on which locomotive could run | 116.67 lb rail | 110.62 lb rail |
| Geometry Relating to Tractive Effort | ||
| Driver Diameter | 74" | 69" |
| Boiler Pressure | 275.60 psi | 250 psi |
| Cylinders (dia x stroke) | 26" x 32" | 26" x 32" |
| Tractive Effort | 68480 lbs | 66620 lbs |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 4.09 | 3.99 |
| Heating Ability | ||
| Firebox Area | 578 sq. ft | 515 sq. ft |
| Grate Area | 96.30 sq. ft | 88.30 sq. ft |
| Evaporative Heating Surface | 4573 | 5443 |
| Superheating Surface | 1438 | 2243 |
| Combined Heating Surface | 6011 | 7686 |
| Evaporative Heating Surface/Cylinder Volume | 232.56 | 276.80 |
| Computations Relating to Power Output (More Information) | ||
| Robert LeMassena's Power Computation | 26540.28 | 22075 |
| Same as above plus superheater percentage | 32889.46 | 28517.13 |
| Same as above but substitute firebox area for grate area | 197405.07 | 166323.02 |
| Power L1 | 35271.46 | 41237.39 |
| Power MT | 1110.86 | 1369.68 |
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