Austrian State 2-12-2 Locomotives in Austria

Class Details by Steve Llanso of Sweat House Media

Class 97.4/297.4 (Locobase 4670)

Data from [] (visited December 2002), a Czech site with an English version that discusses most of the Austrian rack locomotives; "Baureihe 97.4" in Albert Gieseler's Dampfmaschinen und Lokomotiven website at [], last accessed 18 February 2024; and "DR-Baureihe 97.4 (1942)" in at []), last accessed 18 February 2024. (Thanks to Alexander Blessing for his 4 February 2024 email noting the correct adhesion wheelbase Works numbers were 9100-9101 in December 1941.

To handle the greater train loads on the Ezbergbahn in the late 1930s, the BBO designed this much more powerful twelve-coupled tank locomotive pair as Series 369. Before production could begin, Austrian independence fell to the Nazi Anschluss. From then on, locomotive builders in occupied Austria supplied hundreds of Mikados and Decapods to the Third Reich's Deutches Reichsbahn, but somehow the Floridsdorf managed to turn out these two 1'F1';b-nh4t rack locomotives.

(NB: Records show the tube heating surface area was calculated as 195.1 sq m (2,100 sq ft) using the inside (fire side) diameter. Together with the firebox heating surface area, the total evaporative heating surface area came to 210.8 sq m (2,358 sq ft). Locobase used the outside (water side) diameter provided in the same specifications to allow comparison with most locomotives of North American or British manufacture.)

Each of the trucks moved 95 mm to each side on their Adams radial axles. As with most long-wheelbase designs, the 97.4s used side play and shallower flanges to reduce the rigid wheelbase. The first coupled axle enjoyed 25 mm (1") of side play, the sixth coupled axles moved slightly less at 23 mm (0.91"), and the two middle axle drivers used tires with smaller flanges.

Other features inicluded a Giesl ejector stack system and Heinl mixing preheater. The Heinl system sought to raise water temperature using exhaust steam, supplementing those calories with preheated water coming from tanks.

In addition to the two simple-expansion cylilnders outside, the 97.4s used a 400 mm x 500 mm (15.75" x 19.69") rack engine. Unfortunately, noted Wikipedia, the 97.4s "were not satisfactory." They spent much of the time under repair. Rack operation needed to be limited to the south grade between Vordernberg and the Erzberg because the rack in between the rails hadn't been reinforced to handle the increased weight.

After World War II, the 401 served as part source for the 401, which remained in service until 19644.

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID4670
RailroadAustrian State
Number in Class2
Road Numbers97.401-402/297.401-402
Number Built2
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)22.80 / 6.95
Engine Wheelbase (ft / m)37.57 / 11.45
Ratio of driving wheelbase to overall engine wheelbase 0.61
Overall Wheelbase (engine & tender) (ft / m)37.57 / 11.45
Axle Loading (Maximum Weight per Axle) (lbs / kg)36,376 / 16,500
Weight on Drivers (lbs / kg)217,155 / 98,500
Engine Weight (lbs / kg)275,578 / 125,000
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)275,578 / 125,000
Tender Water Capacity (gals / ML)2429 / 9.20
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 3.90 / 3.50
Minimum weight of rail (calculated) (lb/yd / kg/m)
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)41.30 / 1049
Boiler Pressure (psi / kPa)232.10 / 16
High Pressure Cylinders (dia x stroke) (in / mm)24.02" x 20.47" / 610x520
Tractive Effort (lbs / kg)56,417 / 25590.35
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.85
Heating Ability
Tubes (number - dia) (in / mm)150 - 2.244" / 57
Flues (number - dia) (in / mm)34 - 5.63" / 143
Flue/Tube length (ft / m)17.06 / 5.20
Firebox Area (sq ft / m2)168.99 / 15.70
Grate Area (sq ft / m2)41.98 / 3.90
Evaporative Heating Surface (sq ft / m2)2533 / 235.30
Superheating Surface (sq ft / m2)780 / 72.50
Combined Heating Surface (sq ft / m2)3313 / 307.80
Evaporative Heating Surface/Cylinder Volume235.94
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation9744
Same as above plus superheater percentage12,082
Same as above but substitute firebox area for grate area48,636
Power L115,473
Power MT

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