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The reference for locomotives and railcars

Bavarian D IX

German Reichsbahn class 7071

Germany 1888 55 produced
Model of no. 1847

The D IX was built between 1888 and 1899 by Maffei for the Bavarian State Railways, mainly to be used in front of light passenger trains on the Reichenhall-Freilassing-Salzburg line.

The chassis of the engines consisted of two coupled axles with wheels with a diameter of 1,340 mm and a fixed leading axle. Due to the relatively large wheelbase of the driving axles, which were also fixed, there was less than satisfactory running characteristics in curves and increased wear. The two cylinders were located in front of the leading axle, which turned out to be not the most advantageous layout in terms of vibrations.

The maximum speed was 65 km/h, which was sufficient on secondary lines at the time. On the level, the locomotives could reach their top speed with trains up to a maximum of 170 tonnes, but at 2 percent only 20 km/h with a train load of 95 tonnes were possible. In view of the increasingly heavier trains, this performance was soon no longer sufficient, and so the D IX were replaced by six-coupled engines of the D VIII type.

They found their new field of service in the suburban lines of Munich, Nuremberg and Augsburg, where almost all of the 55 locomotives made remained in use until after the First World War. They were assigned to class 7071 from 1925, when their ranks had already thinned out. All the rest were decommissioned by 1932.

Technical data

General

Built
1888-1899
Manufacturers
Maffei
Wheel arrangement
2-4-0T (Porter)
Gauge
1,435 mm (Standard gauge)

Dimensions and weights

Length
8.44 m
Service mass
35.8 t
Adhesion mass
24.8 t
Axle load
12.4 t

Boiler

Grate area
1.2 m²
Evaporative heating surface
60.2 m²
Total heating surface
60.2 m²

Power plant

Driver diameter
1,340 mm
Boiler pressure
12 bar
Expansion type
simple expansion
Cylinders
two, 330 x 500 mm

Power

Power source
steam
Estimated power
150 kW (204 PS)
Top speed
65 km/h
Starting effort
41.4 kN

Calculated values

Factor of adhesion
1 : 5.87
Optimal speed
23 km/h
Power-to-weight ratio
4.2 kW/t
Adhesive weight/Total
1 : 1.44
Tractive force/Heating surface
1 : 14.38
Grate area/Heating surface
1 : 50.17
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