Potlatch Lumber Company 2-6-6-2 "Mallet Mogul" Locomotives in the USA
Class Details by Steve Llanso of Sweat House Media
Class 24 (Locobase 4060)
Data from [
], supplemented by DeGolyer, Volume 80, pp. 248+. See also Jim Wrinn, "Black Hills Central 2-6-6-2T No. 108 is nearing completion" on the Trains magazine newswire for 2 April 2019 at [], last accessed 26 August 2019. Works number was 59087 in March 1926.
One of several Prairie Mallet tanks built by Baldwin for Northwest logging roads. This full saddle-tanker was delivered to its Idaho operator as a coal burner (using bituminous eggnut Montana round-up coal, according to the specs), but was later converted to oil-burning. Its crown sheet was to be sloped to account for an 8% adverse grade. Rail weight remained at 60 lb/yard (30 kg/metre). HP cylinders were supplied through 8" (203 mm) piston valves, while 12" (305 mm) piston valves fed the LP cylinders.
24 had a cabbage stack for a time while with Potlatch, but it had been removed by the time the engine was sold to Weyerhaeuser in 1934 as #108, where she served first at Elk River, Ida., later at Longview, Wash.
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | 24 |
| Locobase ID | 4060 |
| Railroad | Potlatch Lumber Company |
| Country | USA |
| Whyte | 2-6-6-2T |
| Number in Class | 1 |
| Road Numbers | 24 / 108 |
| Gauge | Std |
| Number Built | 1 |
| Builder | Baldwin |
| Year | 1926 |
| Valve Gear | Walschaert |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 16 / 4.88 |
| Engine Wheelbase (ft / m) | 37.75 / 11.51 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.42 |
| Overall Wheelbase (engine & tender) (ft / m) | 37.75 / 11.51 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | |
| Weight on Drivers (lbs / kg) | 193,000 / 87,543 |
| Engine Weight (lbs / kg) | 226,000 / 102,512 |
| Tender Loaded Weight (lbs / kg) | |
| Total Engine and Tender Weight (lbs / kg) | 226,000 |
| Tender Water Capacity (gals / ML) | 2500 / 9.47 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 4 / 4 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 54 / 27 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 44 / 1118 |
| Boiler Pressure (psi / kPa) | 200 / 1380 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 17" x 24" / 432x610 |
| Low Pressure Cylinders (dia x stroke) (in / mm) | 26" x 24" / 660x610 |
| Tractive Effort (lbs / kg) | 37,545 / 17030.15 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 5.14 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | 124 - 2" / 51 |
| Flues (number - dia) (in / mm) | 18 - 5.375" / 137 |
| Flue/Tube length (ft / m) | 17 / 5.18 |
| Firebox Area (sq ft / m2) | 127.40 / 11.84 |
| Grate Area (sq ft / m2) | 26.20 / 2.43 |
| Evaporative Heating Surface (sq ft / m2) | 1653 / 153.62 |
| Superheating Surface (sq ft / m2) | 358 / 33.27 |
| Combined Heating Surface (sq ft / m2) | 2011 / 186.89 |
| Evaporative Heating Surface/Cylinder Volume | 262.30 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 5240 |
| Same as above plus superheater percentage | 6183 |
| Same as above but substitute firebox area for grate area | 30,066 |
| Power L1 | 5482 |
| Power MT | 375.72 |