Deutsche Bundesbahn 4-6-4 Locomotives in Germany


Class Details by Steve Llanso of Sweat House Media

Class BR 78 umbau (Locobase 7907)

Data from Christian Lindecke's German locomotive website -- [link], accessed 24 October 2006.

Two of the famed P8 class of Prussian Ten-wheelers were converted to short-tender locomotives in 1950 by Krupp. A Professor Moelbert of Hanover's technical university apparently combined the facts of hundreds of redundant P8s and the need for commuter-service power in suggesting the modification. The conversion involved adding a four-wheel truck (bogie) under the firebox.

The overhaul proved too expensive to pursue on any scale and the two locomotives remained alone in their class until they were retired ten years later

Principal Dimensions by Steve Llanso of Middle Run Media
ClassBR 78 umbau
Locobase ID7907
RailroadDeutsche Bundesbahn
CountryGermany
Whyte4-6-4T
Number in Class2
Road NumbersDB 78 1001-DB 78 1002
GaugeStd
Number Built2
Builder
Year1951
Valve GearHeusinger
Locomotive Length and Weight
Driver Wheelbase (ft / m)11.81 / 3.60
Engine Wheelbase (ft / m)57.61 / 17.56
Ratio of driving wheelbase to overall engine wheelbase 0.20
Overall Wheelbase (engine & tender) (ft / m)57.61 / 17.56
Axle Loading (Maximum Weight per Axle) (lbs / kg)38,140 / 17,300
Weight on Drivers (lbs / kg)112,656 / 51,100
Engine Weight (lbs / kg)241,847 / 109,700
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)
Tender Water Capacity (gals / ML)3168 / 12
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)5 / 5
Minimum weight of rail (calculated) (lb/yd / kg/m)63 / 31.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)68.90 / 1750
Boiler Pressure (psi / kPa)174 / 1200
High Pressure Cylinders (dia x stroke) (in / mm)22.64" x 24.8" / 575x630
Tractive Effort (lbs / kg)27,287 / 12377.19
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.13
Heating Ability
Tubes (number - dia) (in / mm)
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)15.42 / 4.70
Firebox Area (sq ft / m2)
Grate Area (sq ft / m2)27.76 / 2.58
Evaporative Heating Surface (sq ft / m2)1542 / 143.28
Superheating Surface (sq ft / m2)634 / 58.90
Combined Heating Surface (sq ft / m2)2176 / 202.18
Evaporative Heating Surface/Cylinder Volume133.45
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation4830
Same as above plus superheater percentage6231
Same as above but substitute firebox area for grate area
Power L1
Power MT

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