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The reference for locomotives and railcars

Bavarian D XI (PtL 3/4)

German Reichsbahn class 984-5

Germany 1895 147 produced
98 507 on static display Wolfgang Rieger CC BY 3.0

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
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