This small Michigan railroad bought its motive power in small batches that had differences even within the class. The first two had the EHS (3,905 sq ft) and the number of small tubes (239) as shown. The 182 had 8 more small tubes (247), which increased its total heating surface to 3,991 sq ft. Seven years later, the AA bought 5 more built to a slightly different design; see Locobase 7341.
The Wabash later took over the Ann Arbor and renumbered this class as shown.
These were the post-World War One Mikes for the Ann Arbor. They were middle-of-the-pack 2-8-2s apparently based on the pre-war H class (Locobase 7341). For an increase of two tons of adhesion weight, they gained some addtional heating surface. Moreover, their boilers steamed harder and raised calculated tractive effort by 5,000 lb.
When the Wabash took over the Ann Arbor, they renumbered this class 2490-2494.
| Specifications | ||
|---|---|---|
| Class | H / K6 | H1 / K7 |
| Locobase ID | 7340 | 7341 |
| Railroad | Ann Arbor (AA) | Ann Arbor (AA) |
| Whyte | 2-8-2 | 2-8-2 |
| Road Numbers | 180-182 / 2480-2482 | 183-187 / 2490-2494 |
| Gauge | Std | Std |
| Builder | Alco-Brooks | Alco-Brooks |
| Year | 1917 | 1923 |
| Valve Gear | Baker | Walschaert |
| Locomotive Length and Weight | ||
| Driver Wheelbase | 16.50' | 16.50' |
| Engine Wheelbase | 35.17' | 35.17' |
| Ratio of driving wheelbase to overall engine wheebase | 0.47 | 0.47 |
| Overall Wheelbase (engine & tender) | 67.29' | 67.87' |
| Axle Loading (Maximum Weight per Axle) | ||
| Weight on Drivers | 224500 lbs | 228500 lbs |
| Engine Weight | 294500 lbs | 298000 lbs |
| Tender Light Weight | 176000 lbs | 179500 lbs |
| Total Engine and Tender Weight | 470500 lbs | 477500 lbs |
| Tender Water Capacity | 9000 gals | 9000 gals |
| Tender Fuel Capacity (oil/coal) | 15 tons | 15 tons |
| Minimum weight per yard of rail on which locomotive could run | 93.54 lb rail | 95.21 lb rail |
| Geometry Relating to Tractive Effort | ||
| Driver Diameter | 63" | 63" |
| Boiler Pressure | 185 psi | 200 psi |
| Cylinders (dia x stroke) | 27" x 30" | 27" x 30" |
| Tractive Effort | 54588 lbs | 59014 lbs |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 4.11 | 3.87 |
| Heating Ability | ||
| Firebox Area | 262 sq. ft | 257 sq. ft |
| Grate Area | 70.40 sq. ft | 70.40 sq. ft |
| Evaporative Heating Surface | 3905 | 4063 |
| Superheating Surface | 910 | 1062 |
| Combined Heating Surface | 4815 | 5125 |
| Evaporative Heating Surface/Cylinder Volume | 196.42 | 204.37 |
| Computations Relating to Power Output (More Information) | ||
| Robert LeMassena's Power Computation | 13024 | 14080 |
| Same as above plus superheater percentage | 15485.44 | 16997.65 |
| Same as above but substitute firebox area for grate area | 57630.48 | 62051.08 |
| Power L1 | 13097.94 | 15745.46 |
| Power MT | 514.49 | 607.66 |
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