Prussian S 6

Prussian S 6

Company type	Steam locomotive
Industry	Railway transport
Founded	1906
Founder	Robert Garbe (design proposal)
Headquarters	Breslau (design by Linke-Hofmann-Busch) , Kingdom of Prussia, Germany
Products	Steam locomotives
Number of employees	584 units built (1906–1913)

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The Prussian S 6—which was later classified as the DRG Class 13.10–12—represented a series of German steam locomotives featuring a 4-4-0 wheel configuration, utilized by the Prussian state railways for high-speed express train operations.

Development

Following the underwhelming performance of the earlier Prussian steam locomotive models Prussian S 4 and Prussian S 5, there emerged a demand within Kingdom of Prussia for express locomotives that could deliver enhanced speed and power. In response, in 1904, Robert Garbe, who led the Locomotive Design and Procurement Department, submitted to the Locomotive Committee a proposal for a superheated express engine with a 4-4-0 wheel setup, designed by Linke-Hofmann-Busch of Breslau. This design was an advancement based on the Prussian Class S 4, which also employed the same wheel arrangement.

Garbe was particularly intent on demonstrating that his design outperformed four-cylinder, saturated steam compound engines—especially its predecessor, the Prussian Class Prussian S 7.

The construction of the S 6 was authorized by Garbe in 1905/1906. Over the period from 1906 until 1913, a total of 584 units were produced by manufacturers including Linke-Hofmann-Busch, Henschel-Werke, and the Maschinenbauanstalt Humboldt located in Cologne. These locomotives marked the final series of four-coupled express engines manufactured in Germany and remained among the most fuel-efficient locomotives operated by the Prussian state railways for many years.

Design characteristics

The initial design process presented significant challenges due to the necessity of adhering to the railway network's maximum allowed axle load of 16 t (15.7 long tons; 17.6 short tons).

This restriction prompted extensive weight reduction efforts across various components. Initially, the plate frame was constructed from 22 mm (0.87 in) thick material, but this was later increased to the standard 25 mm (0.98 in) thickness. Early versions of the locomotive featured a smokebox superheater; however, within the first year, this was replaced by a Schmidt smoke tube superheater. Positioning the elongated boiler far forward helped distribute weight towards the front carrying wheels, ensuring compliance with axle load limits and giving the locomotive its distinctive "Garbe" profile.

The S6’s driving wheels had an uncommon diameter of 2,100 mm (82.68 in), selected to reduce revolutions per minute and promote smoother operation of the driving mechanism. Originally, a diameter of 2,200 mm (86.61 in) was planned but was ultimately decreased by 100 mm (3.94 in). The driving gear’s heavy balancing weights were significantly affected by efforts to reduce mass, resulting in pronounced jerking motions during travel. This issue was mitigated by positioning the tender closer to the locomotive, which increased compression on the buffer springs.

It was only after track upgrades in 1910 allowed for a higher axle load of 17-tonne (16.7-long-ton; 18.7-short-ton) that necessary reinforcements could be implemented. Following these modifications, the S 6 became the heaviest 4-4-0 locomotive across continental Europe, surpassing even the later-built four-cylinder saturated steam Class S 7 engines.

Initially, the driver's cab featured a tapered front and conical smokebox doors designed to minimize air resistance. However, this streamlined cab design caused glare issues at night due to reflections from the angled front windows. As a result, from 1908/1909 onwards, cabs were constructed with flat fronts to alleviate this problem.

These locomotives were paired with Prussian Class pr 2’2’ T 21.5 tenders.

Operational capabilities

The S 6 reached a peak indicated power output of 1,160 PS (870 kW or 1,170 hp) when operating at 100 km/h (62 mph). On level terrain, it could continuously pull a train weighing 500 tonnes (490 long tons; 550 short tons), equivalent to 13 eight-wheeled D-Zug coaches, at speeds of around 90 km/h (56 mph). Locomotives equipped with feedwater preheaters demonstrated approximately 10% improved performance.

Allocation

Initial distribution of S 6 locomotives

Division	Number of S6	Division	Number of S6	Division	Number of S6
Altona	70	Elberfeld	23	Kattowitz	21
Breslau	44	Erfurt	17	Magdeburg	41
Bromberg	31	Essen	31	Mainz	9
Cassel	10	Frankfurt	5	Münster	45
Coeln	27	Halle	68	Posen	35
Danzig	21	Hannover	42	Stettin	44

641 Halle at Camp Williams, Is-sur-Tille, France, June 1919. This unit later became Belgian State Railways locomotive number 6641 and remained in service until 1949.

Apart from the railway divisions of Berlin and Königsberg (with some sources also mentioning Saarbrücken), all Prussian railway divisions acquired S 6 locomotives. Transfers between divisions were minimal.

Following the First World War, these locomotives served on express routes such as Leipzig–Dresden and Berlin–Dresden as well as on regular passenger services. A significant number were reassigned to Dresden for operational use.

Preserved locomotives

Beginning in 1912, the S 6 locomotives were replaced by the S 10 for hauling heavy express trains.

Under the 1923 DRG renumbering plan for steam locomotives, a total of 442 S 6 units were scheduled to be renumbered within the range 13 1001 to 13 1442. However, the third and final renumbering scheme reduced this count to 286 machines, assigned numbers from 13 1001 to 13 1286. The final withdrawals of these locomotives in Germany occurred between 1926 and 1931.

Following World War I, as part of reparations, 81 locomotives were transferred to Poland (classified as Pd5), 42 to Belgium (designated type 66), two to Italy (known as class 553), and one to Lithuania.

These locomotives remained operational for considerably longer periods abroad; for instance, Belgium did not retire theirs until 1949.

During Second World War, the Reichsbahn fleet regained possession of 56 S 6 locomotives from Poland, which were renumbered as 13 501 through 13 556.

One example of the S 6 class has been preserved in Warsaw (Poland).

See also

• Prussian state railways
• List of Prussian locomotives and railcars
• List of preserved steam locomotives in Germany

References

• Template:Hütter-01bis45
• Template:Weisbrod-EFA1.1
• Template:Vandenberghen-SNCB12.2

External links

• Photograph of the locomotive in its original form
• Technical drawing with measurements