Pd5

DRG 13 1247, preserved at the former Railway School premises in Warsaw, is the only surviving machine of this class; photo taken on March 15, 2004…

… and another view of the same machine. Its current service number Pd5-17 is fictitious.

DRG Class 13^10-12, side drawing © Lokomotiv-Revue (from TB vol.1)

In Warsaw, 13 1247 was not displayed in a photographer-friendly manner… This photo was taken on July 30, 2001.

KPEV S6; LHW catalogue card from my collection.

Prussian express locomotive S2, which appeared in 1890, became the starting point for the entire family of machines with 2-2-0 axle arrangement. It was designed by August von Borries in a response to a need for faster and more powerful locomotives for express trains. S2 remained basically an experimental machine, but its further derivatives – S3, S4 (first locomotive in the world built in series with Schmidt superheater), S5¹ and S5² – were built in quite large numbers, over 1600 examples combined, and dominated KPEV express trains. All but 104 S4s had compound engines, as von Borries – drawing on British and American experiences – viewed this layout superior due to better economy.

Despite increasing demands concerning tractive power and speed, KPEV decided to maintain the 2-2-0 axle arrangement. Robert Garbe, who designed the next express locomotive for this service, had different ideas concerning economy. His approach was more general; he rejected compound engines, arguing that lower coal consumption did not make up for higher manufacture and maintenance costs. On the other hand, he was a great advocate of steam superheating. After initial experience with express singles (class S4), new class S6 was ordered and supplies began in 1906. They were the heaviest machines in Europe with only two driven axles (it is worth reminding here that in 1906 KPEV received first P8 passenger locomotives with three driven axles), but increase of tractive effort was not impressive: 6.9 tonnes, as compared to 6.2 – 6.4 tonnes of S5¹ and S5². Production was terminated in 1913, after 584 examples had been built by Linke-Hofmann, Henschel and Humboldt. First engines had chamber-type superheater in the smoke box, but this proved unreliable and troublesome in service and was quickly replaced by Schmidt-type one, which was becoming standard. Also oblique front wall of the driver’s cab, intended to reduce drag, but distorting forward view, was replaced in 1908 by more typical flat one. Operational experience was far from unequivocal. Some considered these engines adequate for tasks they had been designed for; other complained of uneasy running (not particularly surprising with only two driven axles) and excessive vibration, caused by poor balancing. Some of these shortcomings were rectified by minor modifications. In those times, when external appearance of locomotives was also appreciated and discussed, S6 – with its two large-diameter drivers shifted backwards and large clearances between wheels – was considered not well-balanced and somehow ancient-looking, especially in comparison with modern engines. It was, however, steam superheating that made it modern.

After WWI, at least 442 machines survived in Germany, but only 286 were taken over by new Deutsche Reichsbahn and designated class 13^10-12. Despite their comparatively young age and large number, they were soon considered obsolete and inadequate for increasing tasks. Due to mounting supplies of new, standardized locomotives, they were fairly quickly withdrawn from service, the last surviving only until 1931. 42 machines taken over by Belgian railways served until 1956. Two S6s served with Italian FS as class 553.

PKP took over 81 ex-KPEV machines, designating them Pd5. They were given service numbers from 1 to 79; two of five machines used in Gdańsk were not given consecutive PKP service numbers and were designated Pd5-1Dz and Pd5-2Dz (Dz standing for ‘Danzig’). Most of them were used with light express and passenger trains, first mainly in north-western Poland (Toruń and Poznań), then also in Warsaw and Wilno. Later they also ran with local trains. They remained in service until 1939. According to LP, 49 machines, captured by Germans, were impressed into DRG and saw a brief service there as class 13⁵ (this designation had formerly been assigned to ex-KPEV class S4, withdrawn much earlier). 22 examples were taken by the Soviets; some were converted to the 1524 mm track (the only engines with two driven axles that underwent such conversion!), but retained their Polish service numbers, written in Russian script. No details on their service history are known, apart from the fact that eleven fell into German hands after Fall Barbarossa; some of them were impressed into service with Ostbahn and retained their ‘original’ service numbers. One engine (Pd5-30, Linke-Hofmann 620/1908), evacuated in 1939 to Lithuania, was impressed into the LG class K5.2 with service number 121; it fell into Soviet hands in 1940. The fate of nine Pd5s remains unknown.

After WWII, 37 machines returned to PKP and were re-designated Pd5-1 through 37. According to KMD, Pd5-7, -19, -28 and -29, in bad condition, were written off before 1948. The last example in service, Pd5-9 (pre-war Pd5-25, later DRG 13 516, Linke-Hofmann 616/1908), was written off on April 8, 1958. Several (probably ten) were transferred to various industrial establishments (most of them as stationary heating machines – obviously they would not make good industrial engines!), but none has been preserved. One S6 can, however, still be seen in Poland. This machine (ex-KPEV Altona 656, then DRG 13 1247, Linke-Hofmann 934/1912, the last of this class in active DRG service) was converted into an educational exhibit before WWII in Braunschweig and used for this purpose – with boiler casing partly removed – until the outbreak of the war. Somehow it found its way to Warsaw, when it was plinthed at the former Railway School premises. In April 2010 this engine was handed over to the PSMK railway fan society and transferred to the Skierniewice depot. It had never served with PKP and its current service number Pd5-17 (previously Pd5-5) is purely fictitious. This is the only S6 that has survived until today.

Class S6 quickly disappeared from service in Germany, as its basic layout was obsolescent almost from the very start. It is a little surprising that KPEV insisted on express machines with two driven axles that had neither good running qualities nor enough tractive effort; in fact, another class of such machines that remained in production for slightly longer – S7, built between 1902 and 1914 (237 examples) – had the 2-2-1 axle arrangement and tractive effort equal to that of S5¹. Major progress came only with class S10, which appeared in 1911.

Main technical data

No.	Parameter	Unit	Value
1.	Years of manufacture	-	1906 – 1913
2.	Total built / used in Poland	-	584 / 81 – 37^1)
3.	Tender class	-	22D1 or 22D2
4.	Axle arrangement	-	2-2-0
5.	Design maximum speed	km/h	110
6.	Cylinder bore	mm	2 X 550
7.	Piston stroke	mm	630
8.	Engine rating	kW/hp
9.	Tractive effort	kG	6 900
10.	Boiler pressure	MPa	1.22
11.	Grate dimensions	m X m	2.35 m^2
12.	Firebox heating surface	m^2
13.	Distance between tube plates	mm
14.	Number of flue tubes	-
15.	Heating surface of flue tubes	m^2
16.	Number of smoke tubes	-
17.	Heating surface of smoke tubes	m^2
18.	Evaporating surface, total	m^2	136.98
19.	Superheater heating surface	m^2	40.32
20.	Diameter of drivers	mm	2100
21.	Diameter of idlers front/rear	mm	1000
22.	Total weight, empty	kg	54 600
23.	Total weight, working order	kg	60 600
24.	Weight on drivers, working order	kg	34 700
25.	Weight with tender, empty	kg	75 500^2)
26.	Weight with tender, working order	kg	108 000^2)
27.	Maximum axle load	T	17.4
28.	Axle base (with tender)	mm	15 065^2)
29.	Overall length (with tender)	mm	18 340^2)
30.	Brake type	-	Westinghouse / Knorr

1) After WWII.

2) With 22D2 tender.

References and acknowledgments

- Monographic article by Paweł Terczyński (SK vol. 12/2001);

- AP, TB vol. 1, LP;

- www.holdys.pl/tomi (website by Tomisław Czarnecki);

- KMD vol. 1/2000 (survey of the 13 1247).