Polson Logging 2-8-2 "Mikado" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class 101 (Locobase 12764)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University, Volume 43, p. 231 and Volume 71, pp. 351+. Works numbers were 38966 in December 1912 and 55355 in April 1922.

Given the other saturated Mikados from Baldwin that entered logging service in the 1910s, the 101 appears to have been a standard design. Indeed, an identical engine was sold to Saginaw Timber at the same time (see Locobase 12765) and Polson bought another with the same specifications a full decade later as its 70.

It was rated to negotiate 30-deg curves. One glitch detected on earlier engines was the equalizing beams between the back truck and the drivers, which apparently tended to break. The specs specifically call for stronger beams and note that "Mr A W Hunger will send information where these beams break." The oil burner used the Von Boden-Ingles oil burner placed in front of the fire pan.

101 served Polson and 1948 successor Rayonier Corporation for more than 40 years before it was scrapped in 1959.

70 had a much more varied fate and its story is still being written. See the Mount Rainier Scenic Railways history of 70 at [] . The 70's retirement from Rayonier in 1963 led to its purchase by Maynard Lang for use by the Puget Sound & Snoqualmie Falls RR Museum at Snoqualmie, WA. A long stint as tourist and work-train locomotive began in 1966 ended with Lang's death in 1992.

When MRSR bought the 70, they knew it would take awhile to get it back into service. See the MRSR's updates leading up to the successful steaming-up on 16 February 2011. "All in all," the account reported, "the #70 ran very well. It is remarkably easy to fire, steams easily, and is a smooth ride."

Class 90 (Locobase 15480)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University, Vol 80, pp. 140+. Works number was 59071 in March 1926.

Polson had bought two Baldwin logging Mikados in 1912 and 1922 (Locobase 12764). These were of a standard Eddystone design and had saturated boilers. When the lumber company returned to Philadelphia for a new engine not quite four years later, it bought a stock design that now had a superheater and more cylinder volume. To feed the larger cylinders the hotter steam, the design used 12" (305 mm) piston valves actuated by outside radial valve gear.

Because it was a stock logging engine, the 90 was designed on the 60 lb/yard (30 kg/metre) rail Polson used. The 3% maximum grades described in the specs were not unusual. At first the 16 degree curves seemed relatively gentle, but a note warned :"Locomotive to be constructed to traverse curves of 30 degrees in event of having these sharper curves on future extensions of company's road."

Polson and successor Rayonier Corporation ran the 90 until 1962, when they sold it to the Oregon Memorial Railroad Society. The ORMS placed the engine on display at Garibaldi, OR.

Principal Dimensions by Steve Llanso of Middle Run Media

Locobase ID12764 15480
RailroadPolson LoggingPolson Logging
Number in Class11
Road Numbers101, 7090
Number Built11
Valve GearStephensonWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)12.08 / 3.6813.08 / 3.99
Engine Wheelbase (ft / m)27.25 / 8.3127.08 / 8.25
Ratio of driving wheelbase to overall engine wheelbase 0.44 0.48
Overall Wheelbase (engine & tender) (ft / m)50.44 / 15.3757.19 / 17.43
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)113,550 / 51,505143,000 / 64,864
Engine Weight (lbs / kg)141,150 / 64,025181,000 / 82,100
Tender Loaded Weight (lbs / kg)80,000 / 36,287110,000 / 49,895
Total Engine and Tender Weight (lbs / kg)221,150 / 100,312291,000 / 131,995
Tender Water Capacity (gals / ML)4000 / 15.155000 / 18.94
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)2000 / 75702000 / 7570
Minimum weight of rail (calculated) (lb/yd / kg/m)47 / 23.5060 / 30
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)44 / 111848 / 1219
Boiler Pressure (psi / kPa)180 / 12.40180 / 12.40
High Pressure Cylinders (dia x stroke) (in / mm)18" x 24" / 457x61020" x 28" / 508x711
Tractive Effort (lbs / kg)27,039 / 12264.7035,700 / 16193.27
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.20 4.01
Heating Ability
Tubes (number - dia) (in / mm)291 - 2" / 51199 - 2" / 51
Flues (number - dia) (in / mm)28 - 5.375" / 137
Flue/Tube length (ft / m)13 / 3.9616.25 / 4.95
Firebox Area (sq ft / m2)140 / 13.01154 / 14.31
Grate Area (sq ft / m2)25.50 / 2.3741.30 / 3.84
Evaporative Heating Surface (sq ft / m2)2108 / 195.912476 / 230.11
Superheating Surface (sq ft / m2)553 / 51.39
Combined Heating Surface (sq ft / m2)2108 / 195.913029 / 281.50
Evaporative Heating Surface/Cylinder Volume298.16243.22
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation45907434
Same as above plus superheater percentage45908772
Same as above but substitute firebox area for grate area25,20032,710
Power L1524311,632
Power MT407.18717.32

  • 90 (Washington University Library)
  • 70 (Photo courtesy Adam Phillips)
  • 90 (Garibaldi, OR photo courtesy John Garbutt)
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