Ok1

Ok1-46, Wrocław Główny depot, September 1961. Photo from my collection.

An Ok1 with a single coach was not an uncommon view on local lines in the 1970s. This beautiful photo of Ok1-334 was taken near Dychów by Geoff Plumb on June 26, 1974 (http://geoff-plumb.fotopic.net – thanks for permission!).

Ok1-325 (ex DRG 38 3267), Henschel 18371/1921 Jaworzyna Śląska loco depot, Poland, August 4, 2004

The same locomotive photographed on October 28, 2005

Ok1-112 (ex DRG 38 1698), Borsig 9076/1915, Kościerzyna loco depot, August 2000. Note incomplete motion gear and enlarged (probably makeshift) smoke lifters.

Ok1-322 (ex DRG 38 3192), Linke-Hofmann, 2269/1921, Wolsztyn loco depot, September 8, 2004

Earlier picture of this machine, taken on April 29, 2002...

...and yet another: May 3, 2008.

Slightly derelict Ok1-266 (ex DRG 38 3587, KPEV Elberfeld 3034), Schichau 2925/1921, Ełk, June 15, 2006.

Another photo of Ok1-266, taken on the same occasion...

... and the other example from Ełk: wreck of the Ok1-258 (ex DRG 38 3272, KPEV Elberfeld 2624), Henschel 18376/1921.

Ok1-198 (ex DRG 38 2402), Schwartzkopff 6947/1919, Żagań depot, April 27, 2007...

... and another photo of this engine, taken on the same occasion.

Class 38^10-40 side drawing from TB vol.1 (© Lokomotiv-Revue).

Ok1-359 (Schartzkopff 6388/1917) appeared at the Steam Locomotive Parade in Wolsztyn on April 28, 2007...

...but I was not particularly lucky in taking pictures: this bald-headed guard and the pole!

Perhaps this rear view is the best one?

More pictures of the Ok1-359, taken at the 2008 Show, can be seen here.

Not excellent in quality, but nice: DRG 38 1259, location and date unknown. Photo from my collection. Probably this is Borsig 7937/1911, ex ‘Essen 2402’, withdrawn from service in 1935; probably, as there was another 38 1259, ex-PKP Ok1-106, captured in 1939.

Prussian state railways KPEV had a particular liking to passenger and even express locomotives with two driven axles: class P4 remained in production until 1911, class S7 – even until 1914. The fact that their tractive effort was not sufficient for heavier drafts was, however, recognized much earlier. This resulted in development of express and passenger locomotives with three driven axles (classes S10 and P6, respectively). Steam superheating was another important novel feature of these machines, offering an alternative to complex and expensive compounds running on saturated steam. Class S10 – the last express locomotive type ordered by KPEV – was built in over 550 examples. On the contrary, class P6 (1-3-0 axle arrangement), introduced in 1901, was not successful. 1600 mm drivers were too small for its design speed and there were problems with weight distribution. Only 275 machines were thus built. Class P7 was an adaptation of Badische Staatsbahn class IVe, designed by Alfred de Glehn and built by Graffenstaden and Maschinenbaugesellschaft Karlsruhe between 1894 and 1901 (73 engines in all). This locomotive featured two-axle lead truck, but its four-cylinder compound engine, running on saturated steam, did not find much favor in KPEV service and only eighteen were delivered in 1901. Class P8, which followed, owed much to earlier P6, but was a new design with two-axle lead truck. Such was the origin of one of the most popular and widely used European locomotives, to be built in almost 4,000 examples.

Beginning of the P8 career certainly did not presage such future. New machine was designed by Robert Garbe in 1905 for passenger and to some extent also light express traffic with maximum service speed of 110 km/h. Prototype was built by Schwartzkopff (s/n 3616/1906) and tests began in August 1906. It soon turned out that boiler design was very successful, despite moderate pressure of only 12 bar (compared to 14 bar in earlier S7), while running qualities left something to be desired; in particular, running was uneasy at high speed. New machine was accepted for production, but some redesign was undertaken: in 1910 diameter of cylinders was reduced from 590 to 575 mm, weight distribution was corrected and maximum service speed was reduced to 100 km/h. Moreover, flat front cab wall replaced the V-shaped previously used, intended to reduce drag. In this ultimate version, P8 finally emerged as a versatile passenger locomotive, reliable and popular among crews.

Production for German railways lasted until 1923 and involved thirteen companies (AEG, Borsig, Hagans, Hanomag, Henschel, Hohenzollern, Humboldt, Jung, Linke-Hofmann, Orenstein & Koppel, Schichau, Schwartzkopff and Vulcan), totaling (according to TB) 3438 examples, the vast majority of them – 3370 – for KPEV. Several locomotives of that type, with only minor modifications, were built for Lithuania, Romania and Poland (see below); production was finally halted in 1928. Furthermore, this machine was license-built between 1932 and 1940 by Malaxa and Reşiţa in Romania. There are some discrepancies between various sources, but most reliable ones give the total number of machines built at 3948 examples.

After WWI, German railways had to hand over 628 P8s to various countries as war reparations – the majority went to Belgium, France and Poland. In post-war DRG service they were re-designated class 38^10-40. Second ‘batch’ of these machines went to several European countries after WWII; it is difficult to estimate how many, but according to some sources German railways were left with 2803 examples, of which many were unserviceable. During post-war service, many of them were fitted with long, narrow smoke lifters, remaining that of German Kriegsloks. DR used their machines until 1972 and DB withdrew last example in January 1975. At least eight machines (possibly more) have been preserved. The following brief account of foreign users is based on sources available to me and I hope to update it soon.

- Belgium (class 64) – 168 examples acquired in 1918, slightly modified, in use until 1966;

- France (classes 230C and 230F) – 162 examples acquired in 1918, several (probably 19) later sold to Poland;

- Romania (class 230.0) – 145 examples acquired from Germany (including 18 ex-KPEV and 14 ex-DRG), 139 examples built by Reşiţa between 1932 and 1940, 87 examples built by Malaxa between 1932 and 1939, service numbers 230.001 to 338, 230.400 to 402, 230.501 to 530 – 371 examples (data from www.railwayfan.ro – this source gives 91 examples built by Malaxa, but only 87 service numbers are quoted);

- Czechoslovakia (class 377.0) – 31 examples impressed into ČSD after WWII, numbers 377.0500 to 0530, plus probably several more not repaired, many were ex-Polish Ok1s, most returned to Poland and Western Germany between 1947 and 1952 (377.0519 was fitted with Riggenbach counter-pressure brake and used for testing other locomotives until 1963, then scrapped);

- Soviet Union – first ‘batch’ comprised Polish Ok1s, captured in September 1939, some later converted to 1524 mm track. Then, in June 1940, after annexation of Bukovina, several CFR 230.0s were acquired, but only two were converted to 1524 mm track and just one was evacuated in June 1941. More German and Romanian machines were captured and impressed into MPS service as Red Army advanced westwards. Probably no Soviet designation was ever allocated and their total number remains unknown. These engines remained in service until early 1950s.

Other foreign users included Lithuania (class K8), Greece (class Zd), Italy, Austria (two heritage ex-CFR engines with fictitious designations, owned by ÖGEG) and Yugoslavia (class 09). Some references also add Turkey, but I have found no trace in Turkish sources (according to www.trainsofturkey.com, TCDD engines Nos. 46001 to 46025 were derived from P8, but had four driven axles).

Poland had the largest fleet of these machines. After WWI, 190 examples were handed over by German railways and re-designated Ok1-1 to Ok1-190; two more were used in Gdańsk and designated Ok1-1Dz and Ok1-2Dz (Dz for ‘Danzig’). This number includes second-hand engines from France. Furthermore, 65 brand new machines were supplied by Linke-Hofmann, Hanomag and Schwartzkopff between 1921 and 1923 and given service numbers from Ok1-201 to Ok1-265. This gives a total of 257 machines. They were used throughout the country and earned a good reputation for manufacturing quality, reliability and ease of maintenance. In 1938, five machines were leased to the French-Polish Railway Company for passenger traffic on the Coal Trunk Line between Upper Silesia and Gdynia (service numbers remained unchanged). Even after the appearance of Ok22 (its direct development – 190 examples built between 1923 and 1934) and much stronger Os24, Ok1 remained the principal passenger locomotive in Poland.

As with other types, in September 1939 Polish Ok1s were divided between Germany and Soviet Union. German examples (about 140) were impressed into class 38^10-40 and some of them were given service numbers of machines withdrawn in 1930s. Some of Soviet machines were converted to 1524 mm track, but exact numbers are not known. After WWII, Polish railways took over 429 machines, so again Ok1 became one of the most numerous and important classes – in fact it was the most important passenger locomotive at least until mid-1950s. Ok1s were held in high esteem due to reliability and high manufacturing quality; despite their age, failure rate was in fact lower than with indigenous Ol49, designed for the same duties. On the other hand, Prussian engine, due to narrow firebox, demanded high-quality coal. In early 1970s there were still about 250 examples in service, but then their number dwindled rapidly and last were withdrawn in 1980. Four of them (Ok1-112, 258, 289 and 303) were for some time used as stationary boilers at various industrial plants. As many as eight machines avoided scrapping, but Ok1-296 (Schichau 2739/1919) was sold to Germany and is now exhibited at Museum für Verkehr und Technik, Berlin, so now seven Ok1s can be seen in Poland. Ok1-359 (Schwartzkopff 6388/1917, ex KPEV Osten 2545, ex DRG 38 2155), based in Wolsztyn, is currently the oldest operational steam locomotive in Poland (Chabówka-based Ol12-7, which is five years older, has seen no service for a couple of years). This engine, withdrawn from service in 2001 due to boiler certificate expiry, underwent major repair and re-appeared in service in November 2006. List of preserved P8s can be found here; this list is probably neither complete nor error-free, so any amendment or correction is most welcome. According to Internet sources (mainly www.enzia.com), as many as 21 locomotives of this type have been preserved in Romania.

Main technical data

No.	Parameter	Unit	Value
1.	Years of manufacture	-	1906 – 1940
2.	Total built / used in Poland	-	3948 / 257 (429^1))
3.	Tender class	-	22D2
4.	Axle arrangement	-	2-3-0
5.	Design maximum speed	km/h	100
6.	Cylinder bore	mm	2 X 575
7.	Piston stroke	mm	630
8.	Engine rating	kW/hp	662 / 900
9.	Tractive effort	kG	10 500
10.	Boiler pressure	MPa	1.22
11.	Grate dimensions	m X m	2.62 X 1.01
12.	Firebox heating surface	m^2	14.58
13.	Distance between tube plates	mm	4 700
14.	Number of flue tubes	-	119
15.	Heating surface of flue tubes	m^2	80.67
16.	Number of smoke tubes	-	26
17.	Heating surface of smoke tubes	m^2	48.0
18.	Evaporating surface, total	m^2	143.25
19.	Superheater heating surface	m^2	52.0
20.	Diameter of drivers	mm	1750
21.	Diameter of idlers front/rear	mm	1000 / -
22.	Total weight, empty	kg	71 700
23.	Total weight, working order	kg	78 200
24.	Weight on drivers, working order	kg	51 600
25.	Weight with tender, empty	kg	94 700
26.	Weight with tender, working order	kg	129 700
27.	Maximum axle load	T	17.7
28.	Axle base (with tender)	mm	15 500
29.	Overall length (with tender)	mm	18 590
30.	Brake type	-	Knorr, Westinghouse

1) After WWII – some sources give 430 examples..

References and acknowledgments

Comprehensive account of this class history and design by Michał ‘Doctor’ Pawełczyk can be found at www.parowozy.best.net. For concise description, see AP. Information on individual examples has been taken mainly from the impressive Ingo Hütter’s locomotive database (available at www.lokomotive.de).