Czechoslovak 375.007 in National Technical Museum, Praha, Czech Republic. July 17, 2003.




Manufacturer’s plate of the 375.007.




Class 310 drawing from EZ vol.2




I hope that these two pictures, taken on June 20, 2009, at the Heizhaus Strasshof, explain why 310 is perhaps the most beautiful steam locomotive ever built.




310.23 (StEG 3791/1911) is operational, but rides only on special occasions. I hope I’ll be there in the right time!




Manufacturer’s plate of the 310.23.



Czechoslovakian 375.006 (former kkStB 310.11, Wiener Neustadt 5058/1911), photographed in Choceň in late 1920s. This engine was withdrawn in March 1949. Photo by Ladislav Lochynský (postcard from my collection).



310.23 with a special Christmas train, photographed at the Wien Traissengasse station on December 24, 1995. Photo by Herbert Ortner, source: Great view!



KkStB 310.23 once again, location and date unknown. Photo from my collection.



Factory photo of the 310.86 (BMMF 551/1915), date unknown. This locomotive remained with BBÖ and was later impressed into DRG as 16 036. Returned after the war, it was withdrawn in August 1952. Source:



Polish actress Helena Grossówna poses by an unidentified Pn12, Kraków, 1934; source: National Digital Archives, used by permission. These 2100 mm drivers are really impressive!



An unidentified kkStB 310, location and date unknown. Source: Die Lokomotive September 1919.



Another unidentified class 310 engine, with Brotan-type boiler. Source: as above.



BBÖ 310.67 (WLF 2208/1914), location and date unknown. In 1938 this engine was taken over by DRG and re-numbered 16 028; after the war it was returned to ÖBB and withdrawn in August 1952. Source: Die Lokomotive April 1925.





In 1908, Austro-Hungarian state railways kkStB (kaiserlich-königliche österreichische Staatsbahnen) received first four-cylinder express locomotives with the 2-3-1 axle arrangement, classed 210. These magnificent and beautiful machines ran on saturated steam; Karl Gölsdorf, who had been responsible for their design, was reluctant to introduce steam superheating due to maintenance problems, mainly the need to use high-grade lubricants resistant to high temperatures. By that time, however, advantages of superheating had already become evident and only eleven 210s were built; nine of them eventually served with PKP as class Pn11, which is described under a separate entry.

Development variant of class 210 with Schmidt-type steam superheater appeared in 1911 and immediately replaced its elder kinsman on production lines. Superheater elements were located in 24 smoke tubes, the number of flues being reduced from 291 to 170. Boiler drum was shortened by 600 mm. Externally, 210 and 310 were very similar – the latter could be distinguished by longer smoke-box. Until 1916, ninety engines were built by BMMF (14), Breitfeld Danĕk (3), StEG (32), Wiener Neustadt (19) and WLF (22). They were followed in 1918 by ten engines from WLF with Brotan-type boilers (in order to save copper, then in short supply), which differed externally in having two larger boiler domes instead of one small – in fact, this spoiled their silhouette to a certain extent. These engines, classed 310.3, were never impressed into service with kkStB, as during wartime there was little need for them; moreover, they turned out to be slightly too heavy for most Austrian tracks. Production ended with the disintegration of Austro-Hungary in 1918. It should be said that, despite beautiful appearance, these locomotives were not entirely satisfactory. Fuel consumption was higher than expected and design speed and tractive effort values were not met. Increased boiler pressure and valve gear modification (from 310.29 onwards) gave some improvement. These shortcomings were in part due to both high-pressure and low-pressure cylinders on each side being served by a single valve gear, which reduced weight and simplified the design, but deteriorated performance, especially at high speed. Suggestions to increase high-pressure cylinders bore to 410 mm were contemplated, but finally rejected. Despite these shortcomings, 310s were the pride and glory of kkStB and hauled the most prestigious express trains in the Austro-Hungarian empire, connecting Vienna with Prague, Salzburg, Eger, Kraków and Lwów (then Lemberg).

All 310s survived until 1918 and, after prolonged negotiations, were divided between Austria, Czechoslovakia and Poland. Austrian state railways ÖBB kept 43 engines; only three were withdrawn before the Anschluss. Czechoslovak railways took over 35 examples, designating them class 375; one was lost in an accident in 1928. Their modernizations included fitting Friedmann-type injectors and modified, flat smoke-box doors. Seven locomotives with Brotan-type boilers were sold directly to Prussian railways KPEV, to become class S11 (‘Berlin 1301’ through ‘1307’, after two years transferred to Kattowitz). In one source I found information that several 310s were taken over by Hungary and Yugoslavia, to become classes 328.5 and 08, respectively; this is not true, as these were different 2-3-0 machines built after WWI.

Poland took over twelve 310s, which were classed Pn12. Furthermore, three machines with Brotan-type boilers were purchased directly from the manufacturer in 1919. In 1922, all Prussian S11s were also handed over to Poland (in accordance with international agreements on Upper Silesia); some older sources give that they were purchased in Germany. Total number of ex-class 310s in Poland was thus 22. In general, ex-Austrian locomotives impressed into the PKP service after 1922, when final agreements had been signed, were usually in bad condition and many classes were represented by single examples. Among such motley collection, Pn12s were considered modern and valuable. They were used mainly in southern and later eastern Poland, at first with express trains, mainly on the Katowice-Kraków-Lwów line. With mounting supplies of Os24s (also with Austrian background) and later Pt31s they were shifted to less prominent routes, but hauled light express trains until 1939 – except for Pn12-3 (BMMF 392/1911), crashed and written off in February 1931. In late 1930s most engines of this class were based in Kowel. Despite supplies of more modern engines they were still valuable, due to low axle load.

In 1939, Germans took over four Pn12s; the rest fell into Soviet hands, but they were not rebuilt for the 1524 mm track and were captured by Germans in 1941. Together with ex-Austrian class 310s, they received DRG designation class 16. Quite logically, they were used mainly in Austria; it is reported they performed quite well, but were difficult to maintain (due to four-cylinder compound steam engines) and rather uneconomical. After 1945, Czechoslovak railways kept their class 375s in use until 1954. In Austria, only five machines were restored into service for a short time, the last one being withdrawn in 1952. Nine ex-PKP examples were returned by ÖBB in 1948 and two by ČSD in 1949. Six were initially erroneously classed Pn11 – in three cases it was never corrected! Their condition was bad and, despite being allocated new serial numbers, assigned to Szczecin regional management and sent to a rolling stock repair works, none of them was restored in service. All were subsequently written off until 1952. For some inexplicable reason, ČSD 375.0503 (ex kkStB 310.51, DRG 16 018, StEG 3876/1913) was transferred to Poland in August 1952. This engine was never given PKP service number and scrapped. Unfortunately, this was the ultimate fate of all Polish Pn12s. In late 1980s the 27D11-5 tender was still at the Warszawa Praga depot, used as a water tank, but was scrapped after this depot had been closed down. Thus, there are now only two surviving examples of Gölsdorf’s most famous design: 375.007 (kkStB 310.15, BMMF 390/1911) on static display at the National Technical Museum in Prague and 310.23 (StEG 3791/1911) in Heizhaus Strasshof – the latter in working order and sometimes hauls special trains.

Locomotives with two rear idle axes never enjoyed much favor in Europe and – apart from these unique Austrian machines – this layout was used mainly in experimental designs, like Bavarian record-breaking S2/6 of 1906 (2-2-2). On the contrary, it found quite widespread use in North America, both in heavy freight machines (1-4-2 or Berkshire – 611 examples and 1-5-2 or Texas – 429 examples) and in lighter ones of more universal type (2-2-2 or Jubilee­ – 30 examples, 2-3-2 or Hudson – 487 examples and 2-4-2 or Northern – 1115 examples; these figures have been taken from Guide to North American Steam Locomotives by George H. Drury). The reason was the same as with the Adriatics – sufficient steam generation with not necessarily high-grade coal.


Main technical data







Years of manufacture


1911 – 1918


Total built / used in Poland


100 / 22 – 121)


Tender class


21D11 (27D112))


Axle arrangement




Design maximum speed




Cylinder bore


2 ´ 390 / 2 ´ 6604)


Piston stroke




Engine rating


1324 / 1800


Tractive force


9 400


Boiler pressure


1.53 (1.63)3)


Grate dimensions

m x m

4.62 m2


Firebox heating surface


15.1 (16.39)2)


Distance between tube plates


5 150


Number of flue tubes




Heating surface of flue tubes




Number of smoke tubes




Heating surface of smoke tubes



Evaporating surface, total


212.9 (200.9)5)


Superheater heating surface




Diameter of drivers




Diameter of idlers front/rear


995 / 995


Total weight, empty


79 200 (77 300)2)


Total weight, working order


86 000 (84 820)2)


Weight on drivers, working order


44 100 (44 560)2)


Weight with tender, empty


102 100

(100 200)2)


Weight with tender, working order


138 600

(129 900)2)


Maximum axle load


14.7 (14.9)2)


Axle base (with tender)


18 236


Overall length (with tender)


21 386


Brake type


Hardy / Westinghouse


1)     Three erroneously designated as Pn11s.

2)     Data in brackets for machines with Brotan-type boilers. Weight data quoted after KT vol. 1; data given in various references differ at least by a few percent.

3)     From 310.29 onwards (from Pn12-6 before WWII).

4)     Some sources give 650 mm, which is probably an error.

5)     Less reliable sources give 195.1 m2

6)     Some sources give 2140 mm, due to different standards used by kkStB.


List of vehicles can be found here.


References and acknowledgments


-       Monographic article by Paweł Terczyński (SK vol. 1/2003);

-       Monographic article by Ryszard Stankiewicz (SS vol. 162);

-       KT vol. 1, LP, EZ vol. 2;

-       Dieter Zoubek (, also private communication – thanks a lot!);

- (website by Josef Pospichal).