Lone batch among Espee Mountains built for the El Paso & Southwestern (but delivered to the SP) with different running gear. Alco works # were 65788-65793.
They were later rebuilt with 28" cylinders and Walschaert valve gear (as in the other batches). Firebox heating surface eventually included 22 sq ft of arch tubes and 94 sq ft in thremic arches. Steam admission came through 14" piston valves.
| Specifications | ||
|---|---|---|
| Class | Mt-1/Mt-3/Mt-4/Mt-5 | Mt-2 |
| Locobase ID | 228 | 1403 |
| Railroad | Southern Pacific (SP) | El Paso & Southwestern (SP) |
| Whyte | 4-8-2 | 4-8-2 |
| Road Numbers | 4300-4327+ | 4385-4390 |
| Gauge | Std | Std |
| Builder | Several | Alco-Brooks |
| Year | 1923 | 1924 |
| Valve Gear | Walschaert | Baker |
| Locomotive Length and Weight | ||
| Driver Wheelbase | 20' | 19.50' |
| Engine Wheelbase | 42.25' | 43.58' |
| Ratio of driving wheelbase to overall engine wheebase | 0.47 | 0.45 |
| Overall Wheelbase (engine & tender) | 83.50' | 83.37' |
| Axle Loading (Maximum Weight per Axle) | 61800 lbs | |
| Weight on Drivers | 246000 lbs | 262000 lbs |
| Engine Weight | 368000 lbs | 391000 lbs |
| Tender Light Weight | 257500 lbs | |
| Total Engine and Tender Weight | 0 | 648500 lbs |
| Tender Water Capacity | 12000 gals | 12300 gals |
| Tender Fuel Capacity (oil/coal) | 4000 gals | 20 tons |
| Minimum weight per yard of rail on which locomotive could run | 102.50 lb rail | 109.17 lb rail |
| Geometry Relating to Tractive Effort | ||
| Driver Diameter | 73.50" | 73.50" |
| Boiler Pressure | 210 psi | 210 psi |
| Cylinders (dia x stroke) | 28" x 30" | 29" x 30" |
| Tractive Effort | 57120 lbs | 61273 lbs |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 4.31 | 4.28 |
| Heating Ability | ||
| Firebox Area | 355 sq. ft | 461 sq. ft |
| Grate Area | 75.70 sq. ft | 84.20 sq. ft |
| Evaporative Heating Surface | 4561 | 5060 |
| Superheating Surface | 1162 | 1380 |
| Combined Heating Surface | 5723 | 6440 |
| Evaporative Heating Surface/Cylinder Volume | 213.33 | 220.63 |
| Computations Relating to Power Output (More Information) | ||
| Robert LeMassena's Power Computation | 15897 | 17682 |
| Same as above plus superheater percentage | 19124.73 | 21471 |
| Same as above but substitute firebox area for grate area | 89686.66 | 117555 |
| Power L1 | 20206.73 | 22192.08 |
| Power MT | 724.36 | 746.95 |
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