OKl2

OKl2-6, loco depot in Jaworzyna Śląska, August 4, 2004…

…another view of the same machine, photo taken on October 11, 2000…

…and yet another picture, taken on the same occasion.

Things are improving: OKl2-6 is no longer posing like it did before, but its condition has greatly improved. Photo taken on July 8, 2009.

Side drawing of the DR class 64 by K.-E. Hertam (TB vol.2)

Ex-DB 64 305, owned by Nene Valley Railway and awaiting overhaul. Wansford, UK, July 23, 2005.

Two photos from my collection, albeit of rather poor quality: 64 035 (Krupp 964/1928)…

…and 64 109 (Jung 4064/1928). Details are lacking, but both look like factory photos.

64 295, DB (Esslingen 4249/1934), photographed at the Waidhaus station on July 19, 1975. Photo by E. Böhnlein (from my collection).

64 295 (Esslingen 4249/1934) in post-war DB livery; Deutsche Dampflokmuseum, Neuenmarkt, May 1, 2014.

64 035 (Krupp 964/1928), location and date unknown. This locomotive survived in the DR service until 1972. Photo from my collection.

64 235 (Orenstein & Koppel 12381/1932), later DB 064 235-5, withdrawn in 1971. Location and date unknown. Photo from my collection.

Last OKl2 in the PKP service, OKl2-20 (Krupp 1288/1933), photographed at the Malbork depot in 1973, probably shortly before withdrawal. Photo by Tadeusz Suchorolski (from my collection).

DRG 64 020 (Henschel 20732/1928), location and date unknown. After the war this locomotive remained with DB and was written off in March 1965. Source: Die Lokomotive April 1928.

DRG 64 018 (Hanomag 10511/1928) also remained with DB; it was re-numbered 064 018-5 and withdrawn in June 1971. Location and date unknown. Source: Die Lokomotive May 1931.

OKl2-1 was in fact a MÁV class 342 engine. This picture shown 342,006, preserved at the Hungarian Railway Museum in Budapest. Photo taken on May 11, 2008, by Balogh Zsolt (source: www.de.wikimedia.org).

ČSD 365.405, ex-DRG 64 347 (Esslingen 4253/1935). This locomotive was withdrawn in October 1962. If my information is correct, this picture was taken in Oščadnica, Czechoslovakia, on May 19, 1971; obviously the engine is in poor condition. Photo from my collection.

After WWI, German railways (newly-formed Deutsche Reichsbahn-Gesellschaft, or DRG) faced a difficult problem of locomotives and rolling stock unification. The Locomotive Commission, formed in 1921, was entrusted the complex task of replacing diverse mixture of types inherited from individual lands’ railways with new family of modern machines, to serve throughout the entire state.

Among other classes, it was soon decided that a light tank locomotive for local traffic, with axle load about 15 tons, was necessary. The 1-3-1 axle arrangement was chosen, although this layout had been almost unknown in Germany, apart from a handful of very unsuccessful Prussian T6s. First preliminary drawings were submitted in 1922 and, after some dispute concerning basic features (including the very layout – some argued that 1-3-2 would be more suitable), Henschel company was asked in September 1924 to prepare the detailed design. This was completed in 1925 and after some further modifications the engine was accepted as class 64. It should be noted that the intention of normalization was realized to a considerable degree: over 79% parts were interchangeable with other classes.

First eight machines were built by Henschel in 1927 and production continued until the end of 1940 to reach 520 examples. By German standards this was not a particularly great number; it is thus somehow surprising that these locomotives were built by as many as fifteen factories. This was intended to keep the German locomotive industry busy, but in the end did not prevent some of these companies from going bankrupt, especially between 1929 and 1931. Thus, class 64 was built by AEG (6), Borsig (13), Esslingen (45), Hagans (14), Hanomag (21), Henschel (31), Humboldt (21), Jung (99), Krauss-Maffei (66), Krupp (65), Linke-Hofmann (13), Orenstein & Koppel (51), Union-Giesserei (40), Schichau (12) and Vulcan (23). Orders for further forty machines from Jung and fifty from Orenstein & Koppel were cancelled. There were minor differences, depending on the manufacturer, some new design features were also tried. Last ten machines (64 510 to 64 520) had Krauss-Helmholtz trucks instead of Bissel idle axes. Twenty-seven had their piston feedwater heater pumps replaced by Friedmann-type injectors; and one was fitted with Lentz-type valve gear (which, despite better economy, proved unreliable, so its development was not proceeded with).

Class 64 proved very successful and found widespread use. It was suitable not only for local traffic, but also for light trains on main lines. After WWII most of them remained in Germany (280 with DB and 115 with DR). They were also used in Austria (only one), Czechoslovakia (about 65, as class 365.4) and Soviet Union (7, as class TY).

After WWII Poland took over thirty-seven examples. They were designated OKl2 and all were given PKP serial numbers. This class, however, included one more locomotive of different type. This was an ex-Hungarian (MÁV) 315,816 (Budapest 4219/1916), originally delivered as 342,919 and later re-numbered 342,885. It was impressed into DRG in November 1944 and later erroneously taken for a class 64 engine (which it in fact resembled). Designated OKl2-1, it was written off in August 1954. Just like in pre-war Germany, class OKl2 locomotives turned out to be quite versatile, serving mainly with suburban and local passenger trains. Five machines were written off until 1956, but rapid withdrawal of this type began in mid-60s. Two remained in the PKP inventory until 1973. The OKl2-6 (Union 2820/1928, ex-DRG 64 061) was written off in Nysa on November 3 and transferred to the Railway Museum in Warsaw. Currently it is on static display at the former locomotive depot in Jaworzyna Śląska (now Industry and Railway Museum). The last one – OKl2-20 (ex 64 272, Krupp 1298/1933) – survived in service only few days longer: after being written off on November 20 in Malbork, it was kept there for further four years and, unfortunately, finally scrapped. OKl2-19 (Schichau 3165/1928, ex 64 118), written off in June 1971, was transferred to Chybie sugar plant; withdrawal date is unknown. As many as fifteen engines of this popular class have been preserved in Germany, many of them in working order. Single examples were sold to:

- Great Britain (Krupp 1308/1934, former DB 64 305, purchased in 1973 by Severn Valley Railway, in 1985 sold to Nene Valley Railway, now awaiting overhaul),

- the Netherlands (Jung 7006/1937, former DB 64 415, now operational with Veluwsche Stoomtrein Maatschappij of Beekbergen),

- Switzerland (Jung 9268/1940, former 64 518, withdrawn in 1972 and sold to Verein Historische Eisenbahn Emmental, now awaiting overhaul)

- Belgium (Henschel 22178/1933, withdrawn in 1970 and later sold to Chemin de Fer à Vapeur des 3 Vallées, Mariembourg-Treignes).

Main technical data

No.	Parameter	Unit	Value
1.	Years of manufacture	-	1927 – 1940
2.	Total built / used in Poland	-	520 / 37^3)
3.	Tender class	-	-
4.	Axle arrangement	-	1-3-1
5.	Design maximum speed	km/h	90
6.	Cylinder bore	mm	2 x 500
7.	Piston stroke	mm	660
8.	Engine rating	kW/hp	580 / 790^1)
9.	Tractive effort	kG	9 700
10.	Boiler pressure	MPa	1.43
11.	Grate dimensions	m x m	1.9 x 1.07
12.	Firebox heating surface	m^2	8.7
13.	Distance between tube plates	mm	3800
14.	Number of flue tubes	-	114
15.	Heating surface of flue tubes	m^2	53.7
16.	Number of smoke tubes	-	32
17.	Heating surface of smoke tubes	m^2	43.0
18.	Evaporating surface, total	m^2	105.4
19.	Superheater heating surface	m^2	37.4
20.	Diameter of drivers	mm	1500
21.	Diameter of idlers front/rear	mm	850 / 850
22.	Total weight, empty	kg	57 900
23.	Total weight, working order	kg	74 700
24.	Weight on drivers, working order	kg	45 500
25.	Weight with tender, empty	kg	-
26.	Weight with tender, working order	kg	-
27.	Maximum axle load	T	15.3
28.	Axle base (with tender)	mm	9 000
29.	Overall length (with tender)	mm	12 400^2)
30.	Brake type	-	Knorr

1) From 1928 tests.

2) 12 400 to 12 500 mm depending on manufacturer and example.

3) Plus one ex-MÁV class 342.

List of vehicles can be found here.

References and acknowledgments

- Monographic article by Roman Witkowski (SK vol. 6/2000);

- Ingo Hütter’s locomotive database (available at www.beitraege.lokomotive.de);

- Attila Kirchner and John Peakman (private communication).