German Field Railway Articulated Locomotives in Germany


Class Details by Steve Llanso of Sweat House Media

Class K66/BR 99.20 (Locobase 3256)

This class originally entered service in the German Army to support narrow-gauge supply routes leading up to the front. They were similar to several other Mallet designs of the same era. After World War I, the Bavarian State System took over these engines to operate on the Eichstaett-Kinding line. At that point they were designated GTS 2x3/3. One eventually worked the Zell-und-Todtnau railway as 105 and was preserved on the Blonay-Chambay museum railway in Switzerland.

Reder's (1974) inclusion of a similar locomotive built for the Zell-und-Todtnau in his discussion of narrow-gauge Mallets, when taken with the 0-4-4-0T from the same line but 29 years older, illustrates how the basic layout could grow to meet requirements. In this case, oddly enough, although total cylinder volume grew, it was all in piston diameter as the stroke remained the same at a relatively short 17.7 in. The drivers, too, didn't grow, but the boiler and overall weight did, the weight more than doubling. This engine had the typical closed-in cab and a not-so-typical vase-like stack. The side tanks were relatively deep, but ended short of the forward, LP cylinders.

Principal Dimensions by Steve Llanso of Middle Run Media
ClassK66/BR 99.20
Locobase ID3256
RailroadGerman Field Railway
CountryGermany
Whyte0-6-6-0T
Number in Class20
Road Numbers
GaugeMetre
Number Built20
BuilderHenschel & Sohn
Year1917
Valve GearHeusinger
Locomotive Length and Weight
Driver Wheelbase (ft / m) 8.20 / 2.50
Engine Wheelbase (ft / m)22.97 / 7
Ratio of driving wheelbase to overall engine wheelbase 0.36
Overall Wheelbase (engine & tender) (ft / m)
Axle Loading (Maximum Weight per Axle) (lbs / kg)19,841 / 9000
Weight on Drivers (lbs / kg)119,048 / 53,999
Engine Weight (lbs / kg)119,048 / 53,999
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)
Tender Water Capacity (gals / ML)
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)
Minimum weight of rail (calculated) (lb/yd / kg/m)33 / 16.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)35.40 / 899
Boiler Pressure (psi / kPa)203 / 1400
High Pressure Cylinders (dia x stroke) (in / mm)15.75" x 17.71" / 400x450
Low Pressure Cylinders (dia x stroke) (in / mm)24.41" x 17.71" / 620x450
Tractive Effort (lbs / kg)30,239 / 13716.20
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.94
Heating Ability
Tubes (number - dia) (in / mm)85 - 1.81" / 46
Flues (number - dia) (in / mm)18 - 5.25" / 133
Flue/Tube length (ft / m)13.78 / 4.20
Firebox Area (sq ft / m2)75.75 / 7.04
Grate Area (sq ft / m2)19.91 / 1.85
Evaporative Heating Surface (sq ft / m2)890 / 82.71
Superheating Surface (sq ft / m2)366 / 34.01
Combined Heating Surface (sq ft / m2)1256 / 116.72
Evaporative Heating Surface/Cylinder Volume222.86
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation4042
Same as above plus superheater percentage5214
Same as above but substitute firebox area for grate area19,837
Power L15697
Power MT633.01

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