Milwaukee Road 2-6-2 "Prairie" Locomotives in the USA


Class Details by Steve Llanso of Sweat House Media

Class K1 (Locobase 815)

Brooks built 125 of these very useful Prairie freight locomotives from 1907-1909, and the Milwaukee Road's (then the Chicago, Milwaukee, & St. Paul) own West Milwaukee shops completed another 70. They burned lignite coal (low-calorie, therefore requiring a large firebox).

Those that weren't superheated were retired in the late 1930s, others lasted until diesels took over in 1the 1950s.


Class K1-as (Locobase 6795)

Data from Milwrd 1930a Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

As big a holding as the Milwaukee had in Prairies (Locobase 815), it only made sense to superheat them. This was the result. The firebox heating surface included 27 sq ft of arch tubes.

Principal Dimensions by Steve Llanso of Sweat House Media
ClassK1K1-as
Locobase ID815 6795
RailroadMilwaukee Road (CMStP&P)Milwaukee Road (CMStP&P)
CountryUSAUSA
Whyte2-6-22-6-2
Number in Class19570
Road Numbers5500-+5500-+
GaugeStdStd
Number Built195
BuilderSeveralSeveral
Year19071920
Valve GearWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)11 / 3.3511 / 3.35
Engine Wheelbase (ft / m)29.25 / 8.9229.25 / 8.92
Ratio of driving wheelbase to overall engine wheebase 0.38 0.38
Overall Wheelbase (engine & tender) (ft / m)60 / 18.2959.81 / 18.23
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)154,500 / 70,080153,950 / 69,831
Engine Weight (lbs / kg)209,000 / 94,801205,550 / 93,236
Tender Loaded Weight (lbs / kg)155,300 / 70,443155,300 / 70,443
Total Engine and Tender Weight (lbs / kg)364,300 / 165,244360,850 / 163,679
Tender Water Capacity (gals / ML)8000 / 30.308000 / 30.30
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)14 / 12.70
Minimum weight of rail (calculated) (lb/yd / kg/m)86 / 4386 / 43
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)63 / 160063 / 1600
Boiler Pressure (psi / kPa)200 / 13.80200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)21" x 28" / 533x71121.5" x 28" / 546x711
Tractive Effort (lbs / kg)33,320 / 15113.7234,926 / 15842.19
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.64 4.41
Heating Ability
Firebox Area (sq ft / m2)238 / 22.12238 / 22.12
Grate Area (sq ft / m2)44 / 4.0944 / 4.09
Evaporative Heating Surface (sq ft / m2)2348 / 218.221980 / 184.01
Superheating Surface (sq ft / m2)412 / 38.29
Combined Heating Surface (sq ft / m2)2348 / 218.222392 / 222.30
Evaporative Heating Surface/Cylinder Volume209.18168.29
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation88008800
Same as above plus superheater percentage880010,296
Same as above but substitute firebox area for grate area47,60055,692
Power L1661912,276
Power MT283.35527.39

Reference