OKo1
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OKo1s were often used with local trains. This engine (OKo1-11, ex KPEV Essen 8918, then DRG 78 379, Vulcan 3892/1922) was photographed by Geoff Plumb (http://geoff-plumb.fotopic.net –
thanks for permission!) near Czempin on
The sole survivor in
Another photo of the OKo1-3,
taken on
…yet another one, taken on the
same occasion...
...and cab interior.
Side drawing of the DR class 781-5
from TB vol.2.
According to my data, this picture of the
OKo1-18 was taken at the Jaworzno depot in May 1960. Photo from my
collection.
TCDD
3705 (Henschel
20554/1925) at the Çamlik Buharli
Lokomotif Muzesi,
78 009, DR, Vulcan
2761/1912, somewhere in Eastern Germany, August 1971. Photo by Werner Nagel
(from my collection). |
KPEV class T18 was the penultimate one
in the long line of Prussian tank locomotives. It was intended as a
replacement of older passenger tank engines (classes T10, T11 and T12),
mainly with commuter and suburban trains, so ability to run at full speed
(100 km/h) in both directions was mandatory. In order to assure good running
qualities during reverse running, a rather exotic axle arrangement 2-3-2 was
chosen, for the first time. Such arrangement, in Europe sometimes referred to
as Baltic, was used in several
locomotive types in Austria, France, Hungary, Spain and The Netherlands, but
none of these was particularly widespread; with a notable exception of
Hungarian class 303, all were tank engines. In North America it was known as Hudson and appeared by a simple
extension of the Pacific with large firebox that had to be supported by a
trailing truck rather than a single axle. Compared to other North American
types, however, Hudsons were not
numerous, totaling less than 500 examples in all. In
T18, axle arrangement resulted in a long locomotive (exactly 3 m longer than
T10) of somehow peculiar appearance. Apart from this, new engine made use of
modern, but already proven design concepts. Boiler was very similar to that
of class P8 with the same moderate pressure of 12 bar. Grate was slightly
shorter and overall heating surface was reduced by a few percent. Cylinder
bore was reduced from 575 to 560 mm, but piston stroke remained unchanged,
although drivers were reduced in diameter by 100 mm. First ten examples were
built by Vulcan-Werke of Stettin
(today Szczecin) and delivered in late 1912 (serial numbers 2753 through
2762). During service tests, T18 proved itself a good and tough machine,
capable of hauling even light express trains: with a 350-tonnes draft, 90
km/h could be easily maintained and running qualities were found very good. KPEV were entirely satisfied with
their new acquisition and immediately ordered it in quantity. Production
engines differed from first ten examples in being fitted with feedwater
heater; maximum speed was increased from 90 to 100 km/h. Until
the end of the war, about 140 examples were accepted by KPEV, all built by Vulcan.
Production against KPEV orders
continued until 1923; in all, 332 engines were given Prussian service numbers
(last of them was ‘Essen 8960’, Vulcan
3916/1923). Apart from these, Vulcan
in 1915 built 28 T18s for the state railways of then-German Alsace-Lorraine;
after WWI they were taken over by SNCF
as class 232TC. From the above-mentioned fleet of KPEV machines, nineteen (assigned to KED Saarbrücken) were in 1920 transferred to the Saarbahnen. The rest were incorporated
into newly-formed Deutsche
Reichsbahngesellschaft (DRG) as
class 781-5; in 1925, they were allocated serial numbers 78 001
through 145, 78 166 through 282 and 78 351 through 401. Between 1923 and
1925, 122 more were built against DRG orders
by Vulcan (69) and Henschel (53), later designated 78 402
through 523; five more were built by Vulcan
at own risk in 1924 and purchased by DRG
in 1927 to become 78 524 through 528. Moreover, 27 examples were built for Saarbahnen by Vulcan, Henschel, Hanomag and Société Franco-Belge de Matériel de Chemins de Fer of La
Croyère, Belgium; when the Saar region was incorporated into the
German Reich in 1935, all T18s owned by Saarbahnen
were taken over by DRG as 78 283
through 328. In
1919, Württembergische Staatsbahn
ordered twenty T18s from Vulcan
(serials 3513 through 3532, service numbers 1121 through 1140); after all
German railways were merged into DRG,
they became 78 146 through 165. Last machines of this type were, quite
surprisingly, built in late 1930s, when private Eutin-Lübecker Eisenbahn (ELE)
ordered a single example from Henschel (23241/1936).
Due to its satisfactory performance, in particular high tractive effort
combined with moderate axle load, second engine was ordered three years later
(24563/1939); it differed from its predecessor in having two sand domes
instead of one, Knorr-Tolkien feedwater pump and in some minor details. On
January 1, 1941, these two engines were taken over by DRG as 78 329 and 78 330. This gives a grand total of 536
examples built for various German railways, of which 508 were included in the
DRG rosters – as far as I know, no
French 232TC was impressed into German service during WWII. Further eight,
with slightly modified boilers, were ordered by Turkish CFOA (Société de Chemins de
Fer Ottoman d’Anatolie) railways. They were built by Henschel in 1925 (serials 20550 through 20557), but delivered to
newly-formed TCDD railways and
given service numbers 3701 through 3708. Four
DRG engines of this type were
written off before the end of the WWII and, of remaining 504 examples, the
majority – 416 – went to DB.
Several were withdrawn immediately afterwards, but 409 remained in use.
Compared to other steam locomotives, their service was quite long: last of
them, 78 246 (Vulcan 3772/1922) was
written off in December 1974. DR
were left with 53 machines; most were written off in early 1960s and the
last, 78 427 (Vulcan 3922/1923)
survived in service until August 1971. Four examples were taken over by the
Soviets and re-numbered 77.xxx (where xxx stood for DRG number); they probably saw very little service, if any.
Czechoslovakian railways ÈSD
acquired (according to www.lokomotive.de)
two machines, which were not restored in service (78 280 and 78 376) and had
no class designation assigned; EZ
confirms only the first of them, scrapped in 1952, but according to this
source there were three more, later transferred to PKP, which in turn is not confirmed by either German or Polish
sources. No
machine of this type served with PKP
before WWII, but after 1945 twenty-nine were acquired and impressed as class
OKo1. Most of them had been built by Vulcan,
except OKo1-22, which was built by Franco-Belge
for Saarbahnen (s/n 2385/1925,
service number 8444, later DRG 78
326). All were assigned to the Poznañ District Management and remained there
throughout their service. They were used mainly with local and suburban
trains and enjoyed a good opinion. Their performance was similar to that of
Ok1 (ex-Prussian P8), tractive effort was almost the same and ability to run
at full speed in both directions made them particularly suitable for secondary
lines, where many terminal stations had no turntables. Later they were
supplemented by indigenous TKt48s, but soldiered on until early 1970s. On
January 1, 1971, twenty-two were still in service and last four, OKo1-15,
-16, -19 and -23, survived until 1975. According to SK, four trucks from scrapped OKo1s are still used for works
transport at the ZNTK (Railway
Stock Repair Works) in Ostrów Wielkopolski. One engine has been preserved:
OKo1-3 (Vulcan 3610/1920, KPEV Essen 8428, then 78 189),
withdrawn in September 1972, it can be seen on static display at the Railway
Museum in Warsaw. Further five T18s have been preserved in Germany and TCDD 3705 (Henschel 20554/1925) can be seen at the Çamlik Buharli Lokomotif Muzesi (Çamlik steam locomotive museum)
in Turkey. Main technical data
1) Plus
eight slightly different engines for 2) Some
sources erroneously give 31. 3) Some
sources give 138.3 m2. 4) 90
km/h in first ten examples. References and acknowledgments
-
http://www-personals.umich.edu/~khmiska
(website by Kurt H.Miska, unfortunately no longer active); -
TB vol.2; -
Lokomotiv-Archiv Württemberg by H.Lohr and G.Thielmann, Transpress,
Berlin, 1988; -
SK, various issues; -
www.lokomotive.de
(locomotive database by Ingo Hütter). |
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