Pk1

DRG 17 008 (BMAG 4760/1911) on display at the Deutsches Technikmuseum, Berlin. Photo taken on May 16, 2009.

Another picture taken on this occasion, showing boiler internal details.

DRG Class 17^0-1, side drawing © Lokomotiv-Revue (from TB vol.1)

In late 19^th and early 20^th century Prussian state railways KPEV (Königlich Preußische Eisenbahnverwaltung) received a considerable number of express locomotives with two driven axles (axle arrangements 2-2-0 and 2-2-1); in fact, their deliveries continued until 1914. Increasing weight of express trains, however, resulted in a need for an engine with more tractive effort, especially for more demanding lines in mountain regions. Third driven axle was necessary, which meant that new locomotive had to be longer and heavier. Steam superheating, which had already proven its advantages, was almost mandatory.

Good starting point for designing such engine was at hand, in the form of very successful passenger locomotive P8. First two prototypes of its development variant with 1980 mm drivers, designated S8, were built by BMAG (Schwartzkopff) in 1910. Boiler and frame were adopted with minimum necessary modifications. Factory tests were, however, somehow disappointing: in particular, boiler capacity was found insufficient. A modified version appeared in 1911. Principal difference were boiler pressure increased from 12 to 14 bar, improved frame, larger grate and enlarged superheater. This variant was ordered by KPEV as S10, but, compared to earlier types, output was rather modest: until 1914, when production was terminated, 202 examples were delivered to KPEV by BMAG, Vulcan and Hanomag (including two prototypes, brought up to this standard). Five more were built by Henschel for Lübeck-Büchener Eisenbahn (LBE); the latter differed in some details and had smaller, three-axle tenders.

Externally – apart from larger drivers – S10 resembled P8, but differed from its passenger counterpart in many important features. Apart from frame and boiler modifications, the four-cylinder single-expansion steam engine was used, with all cylinders driving the first coupled axle. Such engine layout was somehow exotic, at least in Prussia; while assuring smooth running, it was troublesome in maintenance and repairs, as access to inner cylinders was restricted. First and third driven axles were fixed and the second had side-play of 15 mm to both sides. First ten S10s were delivered with four-axle 2’2’T30 tenders, later 2’2’T31.5 with larger water capacity was standardized. Compared to earlier Prussian express engines, with the tractive effort of 6.2 to 6.9 tonnes, S10 delivered 11.4 tonnes with maximum axle load only marginally higher than in 2-2-0 S6 and proved capable of hauling a 390-tonne draft at 100 km/h.

Before WWI these machines, despite their modest number, found widespread use and hauled the most important KPEV express trains. Although successful and powerful for that time, they were considered complex and demanding in maintenance; coal consumption was also comparatively high. S10 was soon developed into S10¹ (four-cylinder compound engine) and S10² (three-cylinder single-expansion unit); both were slightly heavier and more powerful. These engines also served with PKP and shall be described under separate entries.

After WWI, 66 examples, including both rebuilt prototypes, went to several foreign railway managements. In France, eleven were taken over by Nord and one by PLM, but soon all twelve were transferred to Chemins de Fer d’Alsace et de Lorraine and numbered 1150 through 1161. After nationalization they became SNCF class 1-230.H, in 1947 were re-classed 5-230.D. Belgium had sixteen engines, with service numbers from the range 6002 – 6043, in 1946 re-numbered 60.001 through 60.016. (Many thanks to Piotr Staszewski for details on French and Belgian examples.) Smaller numbers went to Lithuania (six), and Italy (FS 676.001, later transferred to France and renumbered 1162). Newly-formed DRG received 135 engines, classed 17^0-1, one was written-off after an accident in 1924. Most were withdrawn between 1927 and 1937; in April 1933 DRG had 48 examples and only six remained in rosters until 1939 (including three fitted with Riggenbach counter-pressure brake and used at the DRG testing establishment in Grünewald). When LBE was absorbed by DRG in 1938, three more followed, numbered 17 141 through 143. Their post-war service was very short: last were withdrawn by DR in 1951. This means that S10s enjoyed comparatively short service life – in many cases less than twenty years. On the other hand, appearance of express Einheitslokomotiven with twice their power rendered them completely obsolete.

Newly-formed Polish state railways received 31 ex-KPEV engines, classed Pk1 (although for Pk1-16, ex Kattowitz 1006, DRG number 17 042 had been initially reserved). Some sources give that this number included two rebuilt prototypes, which is not true. All were still in use in 1939. Together with classes Pk2 (KPEV S10¹) and Pn12 (KkStB 310), they were the most powerful and modern express locomotives in the PKP service, at least until indigenous Pt31 made its appearance. These engines hauled the heaviest and fastest express trains and were routinely employed with transit traffic to/from East Prussia via the so-called Polish corridor. This was a demanding service and 650-tonne drafts were beyond their capabilities; double-heading was not uncommon, and sometimes even Ty23 freighters were used for this purpose, which inevitably resulted in delays. After the September campaign, 26 Pk1s were taken over by Germans and impressed into service with DRG as 17 151 through 175 (no service number is known for Pk1-30 and there is no information on the further fate of this engine). Five fell into Soviet hands, later to be captured by Germans; three were re-numbered 17 176 through 178 and the remaining two were not given DRG numbers. Most of pre-war Pk1s (21) were returned after the war and impressed into service. Besides, PKP obtained also two ex-LBE engines, which became Pk1-4 (formerly LBE 81 ‘Oder’, DRG 17 142) and Pk1-5 (LBE 82 ‘Elbe’, DRG 17 143). Finally, in 1956, DR returned five ex-PKP engines, withdrawn in early 1950s; all were scrapped. Post-war service of this class was comparatively short. Last two examples, Pk1-9 (ex KPEV Trier 1005, then Pk1-14 and 17 162, BMAG 4966/1913) and Pk1-21 (Erfurt 1009, Pk1-19, 17 166, Vulcan 2127/1912) were withdrawn in 1958. In fact they were the last S10s in service. Unfortunately, no Pk1 has been preserved and the only surviving S10 is 17 008 (formerly KPEV Breslau 1008, BMAG 4760/1911), withdrawn in 1935. This engine has its boiler partly cut-out and is on display at the Deutsches Technikmuseum, Berlin. 

Main technical data

No.	Parameter	Unit	Value
1.	Years of manufacture	-	1911 –1914
2.	Total built / used in Poland	-	207^1) / 31
3.	Tender class	-	22D1
4.	Axle arrangement	-	2-3-0
5.	Design maximum speed	km/h	110
6.	Cylinder bore	mm	4 ´ 430
7.	Piston stroke	mm	630
8.	Engine rating	kW/hp	860 / 1170
9.	Tractive effort	kG	11 400
10.	Boiler pressure	MPa	1.43
11.	Grate dimensions	m X m	2.86 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	153.9
19.	Superheater heating surface	m^2	61.5
20.	Diameter of drivers	mm	1980
21.	Diameter of idlers front/rear	mm	1000 / -
22.	Total weight, empty	kg
23.	Total weight, working order	kg	77 500
24.	Weight on drivers, working order	kg	51 700
25.	Weight with tender, empty	kg
26.	Weight with tender, working order	kg	127 300
27.	Maximum axle load	T	17.5
28.	Axle base (with tender)	mm	17 420
29.	Overall length (with tender)	mm	20 750
30.	Brake type	-	Knorr / Westinghouse

1) Including five for LBE, differing in details.

References and acknowledgments

- www.lokomotive.de/lokomotivgeschichte/datenbank (Ingo Hütter’s database);

- LP;

- Piotr Staszewski (private communication).