These relatively small Mikados came to the AB & C in 3 batches (builder's numbers 38-933-38937, 40302-40306, 41739-41743) and were taken into the Atlantic Coast Line as their AK-2. Serving the ACL until 1947-1952, many were then sold to short lines and industrial railroads.
Locobase finds it very hard to believe that the grate area of this large Mikado design was truly as small as 43.3 sq ft, yet the diagrams from 1930 and 1943 insist upon it. The earler diagram had an impossibly high heating surface figure that was revised down by more than 1,000 sq ft. But the ratios were still very high and the factor of adhesion quite low.
| Specifications | ||
|---|---|---|
| Class | K-2 | K-3 |
| Locobase ID | 7859 | 7860 |
| Railroad | Atlanta, Birmingham & Atlantic (AB&C) | Atlanta, Birmingham & Atlantic (AB&C) |
| Whyte | 2-8-2 | 2-8-2 |
| Road Numbers | 92-106 / 201-215 | 301-302 |
| Gauge | Std | Std |
| Builder | Baldwin | Baldwin |
| Year | 1912 | 1910 |
| Valve Gear | Walschaert | Baker |
| Locomotive Length and Weight | ||
| Driver Wheelbase | 15' | 16' |
| Engine Wheelbase | 32.33' | 33' |
| Ratio of driving wheelbase to overall engine wheebase | 0.46 | 0.48 |
| Overall Wheelbase (engine & tender) | 65.07' | 64.27' |
| Axle Loading (Maximum Weight per Axle) | 46750 lbs | 50200 lbs |
| Weight on Drivers | 187000 lbs | 200000 lbs |
| Engine Weight | 249900 lbs | 266100 lbs |
| Tender Light Weight | 142000 lbs | 142000 lbs |
| Total Engine and Tender Weight | 391900 lbs | 408100 lbs |
| Tender Water Capacity | 7500 gals | 7500 gals |
| Tender Fuel Capacity (oil/coal) | 12 tons | 12 tons |
| Minimum weight per yard of rail on which locomotive could run | 77.92 lb rail | 83.33 lb rail |
| Geometry Relating to Tractive Effort | ||
| Driver Diameter | 57" | 57" |
| Boiler Pressure | 185 psi | 200 psi |
| Cylinders (dia x stroke) | 24" x 30" | 25" x 32" |
| Tractive Effort | 47672 lbs | 59649 lbs |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 3.92 | 3.35 |
| Heating Ability | ||
| Firebox Area | 210 sq. ft | 210.30 sq. ft |
| Grate Area | 51.90 sq. ft | 43.30 sq. ft |
| Evaporative Heating Surface | 3156 | 3686 |
| Superheating Surface | 663 | 854 |
| Combined Heating Surface | 3819 | 4540 |
| Evaporative Heating Surface/Cylinder Volume | 200.92 | 202.74 |
| Computations Relating to Power Output (More Information) | ||
| Robert LeMassena's Power Computation | 9601.50 | 8660 |
| Same as above plus superheater percentage | 11268.37 | 10289.00 |
| Same as above but substitute firebox area for grate area | 45594.58 | 49971.73 |
| Power L1 | 11382.16 | 12983.49 |
| Power MT | 536.76 | 572.47 |
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