The reference for locomotives and railcars
Saxon IV K
German Reichsbahn class 9951-60
Germany | 1892 | 96 produced
No. 107, the fifth machine built, on a Hartmann factory photo
No. 107, the fifth machine built, on a Hartmann factory photo

With 96 examples, the IV K was the most numerous narrow-gauge steam locomotive in Germany. Its special feature is the design based on the Meyer design with two bogies, which was due to the requirements for increased tractive effort. Since the six-coupled locomotives of classes I K and III K that had been used up to that point were no longer sufficient for all operations, the answer was a new locomotive with four coupled axles. In order to achieve good negotiation of curves, the special arrangement of the chassis was used.

In contrast to the Mallet, both parts of the chassis of this type of locomotive were designed as swiveling bogies. Furthermore, the cylinders were on the inside of the bogies, but this was also a compound engine. Due to the arrangement of the cylinders, shorter tubes were sufficient. Otherwise, the IV K shared some assemblies with the III K, which is partly recognizable. The model was immediately convincing, which is why production ran from 1892 to 1921. It was used on all narrow-gauge lines in the Saxon network.

After two locomotives were lost during World War I and three more had to be handed over to Poland, the Reichsbahn took over the rest as class 9951-60. There they also came to the Rügen Light Railway and the Prignitz Light Railway.

After a few units had already been taken out of service in the meantime, another 57 units came to the Reichsbahn of the GDR. There the plan was to replace them in the 1960s with the newly developed diesel locomotives V 3648. However, since the axle loads on these were far above the permitted level and they were therefore not produced in series, the steam locomotives had to remain in use. Only the oldest locomotives were retired during this time. In the period that followed, all remaining locomotives received a thorough modernization, which included, among other things, a new, welded boiler and a welded frame. So it turned out that after the German reunification there were still 13 units in active service. After two of them had been sold, Deutsche Bahn AG took over eleven more in 1994. However, these were no longer used as planned.

Variantlight variantheavy variant
Axle config0-4-0+0-4-0T (Günther-Meyer) 
Gauge2 ft 5 1/2 in
Dimensions and Weights
Length29 ft 6 5/16 in
Wheelbase20 ft 4 1/8 in
Fixed wheelbase4 ft 7 1/8 in
Empty weight47,840 lbs49,383 lbs
Service weight59,084 lbs62,832 lbs
Adhesive weight59,084 lbs62,832 lbs
Axle load14,771 lbs15,873 lbs
Water capacity634 us gal
Fuel capacity1,874 lbs (coal)2,249 lbs (coal)
Power sourcesteam
Indicated power207 hp (154 kW)
Optimal speed14 mph11 mph
Top speed19 mph
Starting effort9,295 lbf12,143 lbf
with start valve11,154 lbf14,572 lbf
Power Plant
Driver diameter29.9 in
Boiler pressure174 psi218 psi
Expansion typecompound
Cylindersfour, HP: 9 7/16 x 14 15/16 in
and LP: 14 9/16 x 14 15/16 in
four, HP: 9 7/16 x 14 15/16 in
and LP: 15 3/4 x 14 15/16 in
Grate area10.4 sq ft
Firebox area43.8 sq ft
Tube heating area492.3 sq ft
Evaporative heating area536.2 sq ft
Total heating area536.2 sq ft
Calculated Values
steam locomotive
tank locomotive
narrow gauge
last changed: 04/2022

We use cookies to save the following settings:

  • selected navigation structure
  • selected language
  • preferred units
  • spelling of railway company names

If you refuse the use of cookies, the settings will only be retained for the current session and will be reset to the default values the next time you visit the site.

Display of units

Here you can set the desired unit system for the technical data.

  • Metric: Lengths in meters, weights in tonnes, and volumes in cubic meters
  • Imperial (UK): Lengths in feet/inches, weights in long tons and volumes in imperial gallons
  • Imperial (US): Lengths in feet/inches, weights in pounds, and volumes in US gallons
  • Individual: Depends on the country of origin of each locomotive
Operator names

Here you can set the display of railway company names.

  • Short: Abbreviation or short form of the name
  • Standard: commonly used name, partially translated to English
  • Complete: full name in local language