Bavarian D XI (PtL 3/4)
German Reichsbahn class 984-5
The D XI, also known by its later designation PtL 3/4, was the most numerous of the Bavarian local railway locomotives. It was designed and built simultaneously by Krauss and Maffei and procured over a period of 19 years. Externally, they were very similar to the D VIII, which had been in production for a number of years, but they were intended more for flat lines and were therefore somewhat lighter and weaker. On the other hand, the coal bunker was larger, since the greater weight on the trailing axle, which was placed far to the rear, had less of a negative effect on the driving characteristics on flat land than on inclines.
Due to the long distance of the trailing axle, this was linked to the rear drivers by a Krauss-Helmholtz bogie, as had already been used on the D VIII. The brakes on the locomotive were also state-of-the-art, and despite the changed tasks, a Riggenbach counter-pressure brake was used in addition to the counterweight brake and the modern Westinghouse air brake.
In addition to the state railway, the LAG also bought eight locomotives from Krauss, which were later bought up by the state railway. There were also three which came to the state railways from the Murnau–Kohlgrub–Oberammergau light railway via the LAG. Thus the total number of D XI or PtL 3/4 numbered 147 by 1914. A model derived from them was the Palatinate T 4II, which was only built three times and had slightly different dimensions. After the war, all locomotives came to the Reichsbahn and became the class 984-5. About half were retired in the early 1930s. After a few losses in World War II, the Bundesbahn took over 56, the last of which was in use until 1960.
Technical data
General
- Built
- 1895-1914
- Manufacturers
- Krauss, Maffei
- Wheel arrangement
- 0-6-2T (Webb)
- Gauge
- 1,435 mm (Standard gauge)
Dimensions and weights
- Length
- 9.26 m
- Service mass
- 39.1 t
- Adhesion mass
- 31.1 t
- Axle load
- 10.9 t
- Water capacity
- 4,300 l
- Fuel capacity
- 1.5 t (coal)
Boiler
- Grate area
- 1.34 m²
- Firebox surface
- 5.26 m²
- Tube heating surface
- 62.44 m²
- Evaporative heating surface
- 67.7 m²
- Total heating surface
- 67.7 m²
Power plant
- Driver diameter
- 1,006 mm
- Boiler pressure
- 12 bar
- Expansion type
- simple expansion
- Cylinders
- two, 375 x 508 mm
Power
- Power source
- steam
- Indicated power
- 235 kW (320 PS)
- Top speed
- 45 km/h
- Starting effort
- 72.4 kN
Calculated values
- Factor of adhesion
- 1 : 4.21
- Optimal speed
- 19 km/h
- Power-to-weight ratio
- 6.0 kW/t
- Heating Surface Equivalent
- 94.0 m²
- Cylinder volume/HSE
- 1 : 1,193.76
- Adhesive weight/Total
- 1 : 1.26
- Tractive force/Heating surface
- 1 : 22.34
- Grate area/Heating surface
- 1 : 50.52
- Firebox/Tube surface
- 1 : 11.87