Prescott & Northwestern 2-8-2 "Mikado" Locomotives in the USA


Class Details by Steve Llanso of Sweat House Media

Class 15 (Locobase 13927)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University, Volume 52, p. 393. Works numbers were 37914 in June 1912 and 43057 in March 1916.

The second Mikado was named the D F Andrews and its specification anticipated an adhesion weight of 137, 500 lb and total engine weight of 176,000 lb. The specs made a special point of saying: "Loco. is intended for the very hardest kind of service and the greatest care should be exercised in looking after the details of design and manufacture."

After more than 35 years in service on the P & N, the 17 went to the Arkansas Railroad sometime after November 1951. According to Gene Connelly's master list of Baldwin locomotives, however, it was never relettered for the AR.


Class R F Smith (Locobase 13929)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University, Volume 52, p. 391. Works number was 41381 in May 1914.

Bought by Ozan-Graysonia Lumber for the P & N, the 16 was smaller, lighter, and less powerful than the 15 that had gone into service a couple of years before. The specs described the line as having a maximum 5% grade, curves as sharp as 30 degrees in radius on 56-lb/yard (28-kg/metre) rail.

The 16 served both for about 20 years before being sold to the Union Saw Mill in November 1936. Sometime later the engine wound up on the Louisiana & Pine Bluff.

Specifications by Steve Llanso of Sweat House Media
Class15R F Smith
Locobase ID13,927 13,929
RailroadPrescott & NorthwesternPrescott & Northwestern
CountryUSAUSA
Whyte2-8-22-8-2
Number in Class21
Road Numbers15, 1716
GaugeStdStd
Number Built21
BuilderBaldwinBaldwin
Year19121914
Valve GearWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)13.08 / 3.9912.08 / 3.68
Engine Wheelbase (ft / m)27 / 8.2327.30 / 8.32
Ratio of driving wheelbase to overall engine wheebase 0.48 0.44
Overall Wheelbase (engine & tender) (ft / m)57.12 / 17.4151.46 / 15.69
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)134,000 / 60,781111,000 / 50,349
Engine Weight (lbs / kg)173,000 / 78,472136,000 / 61,689
Tender Loaded Weight (lbs / kg)110,000 / 49,89580,000 / 36,287
Total Engine and Tender Weight (lbs / kg)283,000 / 128,367216,000 / 97,976
Tender Water Capacity (gals / ML)5500 / 20.834000 / 15.15
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)6 / 5.507 / 6.40
Minimum weight of rail (calculated) (lb/yd)5646
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)48 / 121944 / 1118
Boiler Pressure (psi / kPa)160 / 11180 / 12.40
High Pressure Cylinders (dia x stroke) (in / mm)20.5" x 28" / 521x71118" x 24" / 457x610
Tractive Effort (lbs / kg)33,340 / 15122.7927,039 / 12264.70
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.02 4.11
Heating Ability
Firebox Area (sq ft / m2)158 / 14.68140 / 13.01
Grate Area (sq ft / m2)41.30 / 3.8425.50 / 2.37
Evaporative Heating Surface (sq ft / m2)3166 / 294.131918 / 178.19
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)3166 / 294.131918 / 178.19
Evaporative Heating Surface/Cylinder Volume295.98271.34
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation66084590
Same as above plus superheater percentage66084590
Same as above but substitute firebox area for grate area25,28025,200
Power L147344889
Power MT311.54388.41