Data from [] and DeGolyer, Volume 80, pp. 373. (Thanks to Chris Hohl for his 6 April 2025 email correcting the engine-and-tender length.) Works number was 60837 in May 1929 and 61753 in 1933. Price in 1929 was $63,637.
Note: Locobase convention for Mallet and other articulated and semi-articulated locomotives calculates the adhesion wheelbase as the sum of the two driver-set wheelbases. Baldwin's figure for the engines' driving wheelbase gives the total distance between the first driving axle of the front engine to the rearmost driving axle of the rear engine as 31 ft 9 in (9.68 m).
Although relatively small for the wheel arrangement, this pair of Mikado Mallets were comparative behemoths on a logging road that used 60 lb/yard (30 kg/metre) rail, scaled 4% grades, and negotiate curves of up to 25 degrees. The HP cylinders were cast separately and attached to an intermediate saddle of cast steel while the LP cylinders were cast integrally with half saddles and bolted together at the center.
Locobase suspects that Weyerhaeuser thought the HP cylinders were subject to too much stress to use the more common cylinder-half saddle casting method. All four cylinders got their steam through 12" (305 mm) piston valves.
Both operated in Washington State until scrapped in 1953.
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | 200 |
| Locobase ID | 4046 |
| Railroad | Weyerhaeuser Timber |
| Country | USA |
| Whyte | 2-8-8-2 |
| Number in Class | 2 |
| Road Numbers | 200-201 |
| Gauge | Std |
| Number Built | 2 |
| Builder | Baldwin |
| Year | 1929 |
| Valve Gear | Walschaert |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 27 / 8.23 |
| Engine Wheelbase (ft / m) | 50 / 10.90 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.54 |
| Overall Wheelbase (engine & tender) (ft / m) | 77.50 / 15.24 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | 40,000 / 18,144 |
| Weight on Drivers (lbs / kg) | 320,000 / 145,150 |
| Engine Weight (lbs / kg) | 355,000 / 161,025 |
| Tender Loaded Weight (lbs / kg) | 143,000 / 64,864 |
| Total Engine and Tender Weight (lbs / kg) | 498,000 / 225,889 |
| Tender Water Capacity (gals / ML) | 7000 / 26.52 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 2500 / 9463 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 67 / 33.50 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 51 / 1295 |
| Boiler Pressure (psi / kPa) | 215 / 1480 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 23" x 28" / 584x711 |
| Low Pressure Cylinders (dia x stroke) (in / mm) | 35" x 28" / 889x711 |
| Tractive Effort (lbs / kg) | 74,137 / 33628.02 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 4.32 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | 174 - 2.25" / 57 |
| Flues (number - dia) (in / mm) | 40 - 5.53" / 140 |
| Flue/Tube length (ft / m) | 21 / 6.40 |
| Firebox Area (sq ft / m2) | 290 / 26.94 |
| Grate Area (sq ft / m2) | 64.50 / 5.99 |
| Evaporative Heating Surface (sq ft / m2) | 3639 / 338.20 |
| Superheating Surface (sq ft / m2) | 985 / 91.54 |
| Combined Heating Surface (sq ft / m2) | 4624 / 429.74 |
| Evaporative Heating Surface/Cylinder Volume | 270.35 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 13,868 |
| Same as above plus superheater percentage | 16,780 |
| Same as above but substitute firebox area for grate area | 75,444 |
| Power L1 | 8179 |
| Power MT | 450.79 |