Portland, Astoria & Pacific 2-8-2 "Mikado" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class 100 (Locobase 14275)

Data from http://www.trainboard.com/grapevine/group.php?discussionid=884&do=discuss. See also Edward J. Kamholz, Jim Blain, Gregory Kamholz, The Oregon-American Lumber Company: Ain't No More, (Stanford University Press, 2003), p. 53. Works numbers were 61857, 61859 in 1920.

The first of three oil-burning logging Mikados was delivered with the PA&P herald on the tender, but the other two were sent directly to the Oregon-American Lumber Company. The design was of a typical size for a logger and had nice lines on a relatively long wheelbase. According to the Kamholz-Blain-Kamholz book, the PA&P intended these as mainline engines to handle a 40-mile run to Rafton.

When that railroad was taken over by the Eccleses, however, they concluded that the three should be used for logging traffic. But they were big and that long wheelbase was but one reason, says the trio, that these engines were "miscast for their new role as woods engines." In fact, 101 never actually operated on the O-A, being sold instead to California's Minarets & Western; see Locobase 14276. 100 was barely used at all before being shelved and 102 was too heavy for the unballasted rail.

Principal Dimensions by Steve Llanso of Sweat House Media
Locobase ID14,275
RailroadPortland, Astoria & Pacific
Number in Class3
Road Numbers100, 102
Number Built3
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)14.25 / 4.34
Engine Wheelbase (ft / m)
Ratio of driving wheelbase to overall engine wheebase
Overall Wheelbase (engine & tender) (ft / m)
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)136,000 / 61,689
Engine Weight (lbs / kg)176,000 / 79,832
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)
Tender Water Capacity (gals / ML)5000 / 18.94
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)1800 / 6.80
Minimum weight of rail (calculated) (lb/yd / kg/m)57 / 28.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)48 / 1219
Boiler Pressure (psi / kPa)180 / 12.40
High Pressure Cylinders (dia x stroke) (in / mm)20" x 28" / 508x711
Tractive Effort (lbs / kg)35,700 / 16193.27
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.81
Heating Ability
Firebox Area (sq ft / m2)
Grate Area (sq ft / m2)43.30 / 4.02
Evaporative Heating Surface (sq ft / m2)
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)
Evaporative Heating Surface/Cylinder Volume
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation7794
Same as above plus superheater percentage7794
Same as above but substitute firebox area for grate area
Power L1
Power MT

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