military railroads Articulated Locomotives in Germany

Class Details by Steve Llanso of Sweat House Media

Class K44.9 / BR 99.5906 et al (Locobase 4861)

Data from J D Pare, "G 2+2/2 105 Snddeutsche Eisenbahn Gesellschaft" on the Blonay-Chamby website at [] (originally []) last accessed 8 November 2020; [], and [] (visited 4 October 2003). See also [] . See also the Harz Narrow-Gauge Railways (HSB) site) at

To support German operations against the fortress of Verdun, the military requisitioned locomotives from all over Western Germany. But the authorities were concerned that such impressments would interfere with industrial operations, says the Blonay-Chamby website, and seven small Mallets were ordered from Karlsruhe. The design had long side tanks, an enclosed cab, and LP cylinders forward, HP behind.

The design was based on the Nordhausen-Wernigeroder Eisenbahn (NWE) engines of 1897, but with larger boiler, but lower boiler pressure

In the meantime, however, came the Armistice and these engines didn't have a job. They went into private use on schmalspur lines in eastern Germany, including those of the NWE.

According to after the division of Germany in 1945-48, these engines went to the Selketal Railway where their ability to handle very sharp curves meant that several stayed in service into the 1980s.

HSB took over the services of Deutsche Reichsbahn, the East German State Railways (DR) on 2 February 1993 and operates three of the former NWE engines, including two of this later class.

The one that would later be owned by Blonay-Chamby at first lay idle for three years and then entered service in 1921 with the Haspe-Voerde-Breckerfeld railway as #28. When the HVB electrified in 1928, she went to the Zell-und-Todtnau in the Black Forest. There, as 105, she operated for nearly 4 decades. After the Z-und-T closed in 1968, she came to the Blonay-Chamby as the museum railway's first steam locomotive. A five-year overhaul in which 90% of the boiler was renewed allowed her return to service.

See data from for data.

[] comments that "The 5906 is somewhat longer and lower that its 'stablemates', the 99 5901 to 99 5903. It also has some other peculiar design features. Whilst both of these locomotives feature an extermal frame for the high pressure drive, the 99 5906 is rekitted to a compressed-air brake system both for the pivoted bogie and for the high-pressure driving mechanism. Previous models were still being braked directly with steam! And that was a risky procedure. If the braking cylinder was cold, it took a moment for the brake to work because the fresh steam had to condense first of all.

Another special feature is the flat slide valve regulator. It comes with a greasing point on the regulator dome. The locomotive has previously been greased using a sluice. Nowadays there is an oil stop there which is supplied from the engine's central greasing reservoir.

Other interesting features includes the firebox door and the oval fire hole in the boiler. Passengers cannot travel in the driver's cabin on the Mallets as it is even very cramped for two people. However, you can have a good view of the driver's cabin if you stand on the platform of the carriage behind the locomotive and if the train driver leaves the window on the rear wall of his cabin open during the summer months. You can also see and admire the firebox door from there; it looks rather like a bathstove. That is why some of the train drivers talk about the "bathstove" on the 99 5906. No other type of door design would work here because of the shape of the fire hole."

Principal Dimensions by Steve Llanso of Middle Run Media

ClassK44.9 / BR 99.5906 et al
Locobase ID4861
Railroadmilitary railroads
Number in Class7
Road Numbers
Number Built7
Valve GearHeusinger
Locomotive Length and Weight
Driver Wheelbase (ft / m) 4.59 / 1.40
Engine Wheelbase (ft / m)15.32 / 4.67
Ratio of driving wheelbase to overall engine wheelbase 0.30
Overall Wheelbase (engine & tender) (ft / m)
Axle Loading (Maximum Weight per Axle) (lbs / kg)19,842 / 9000
Weight on Drivers (lbs / kg)79,366 / 36,000
Engine Weight (lbs / kg)79,366 / 36,000
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)79,366 / 36,000
Tender Water Capacity (gals / ML)1003 / 3.80
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 4.40 / 4
Minimum weight of rail (calculated) (lb/yd / kg/m)33 / 16.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)39.40 / 1000
Boiler Pressure (psi / kPa)174 / 12
High Pressure Cylinders (dia x stroke) (in / mm)11.02" x 19.69" / 280x500
Low Pressure Cylinders (dia x stroke) (in / mm)16.73" x 19.69" / 425x500
Tractive Effort (lbs / kg)12,520 / 5678.98
Factor of Adhesion (Weight on Drivers/Tractive Effort) 6.34
Heating Ability
Tubes (number - dia) (in / mm)133 - 1.85" / 47
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)11.81 / 3.60
Firebox Area (sq ft / m2)59.96 / 5.57
Grate Area (sq ft / m2)14.64 / 1.36
Evaporative Heating Surface (sq ft / m2)731 / 67.87
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)731 / 67.87
Evaporative Heating Surface/Cylinder Volume336.30
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation2547
Same as above plus superheater percentage2547
Same as above but substitute firebox area for grate area10,433
Power L12351
Power MT261.22

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