OKl27
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OKl27-41 (HCP
270/1932), preserved at Chabówka loco heritage
park, photographed in June 2001.
OKl27-26 (HCP
223/1931), displayed at the
Another picture of this engine: September 19, 2010.
OKl27-25 (HCP
172/1930), location and date unknown – possibly a factory photo. Captured by
Germans, this engine was impressed into DRG
as 75 1225. Returned after the war, it became OKL27-10 and was withdrawn in
December 1979. Source: National Digital
Archives (used by permission).
OKl27-10 (ex OKl27-25) is currently owned by PSMK railway fans society and plinthed
at the Skierniewice loco depot. Photo taken on
Another photo of the OKl27-10, taken on the same
occasion; shorter right water box can be easily seen.
OKl27 side drawing from PNP.
This OKl27-27 (HCP
227/1931) is plinthed at the Gdynia Grabówek loco depot; photo taken on
Another picture of the OKl27-27, taken on
OKl27-31, photographed somewhere in
OKl27-115 (HCP
294/1933) crashed a timber store in Mysłowice on
January 15, 1937. This engine became DRG
75 1300 after September 1939; finally returned in 1947, remained in use as
OKl27-58 until June 1976. Source: National Digital
Archives (used by permission).
OKl27-26 again: Stacja Muzeum
(previously Railway Museum), Warsaw, July 6, 2023. |
Few
locomotives acquired by PKP after
WWI were suitable for suburban traffic; this service required fast startups
and frequent stops, as well as possibility to run at full speed in both
directions. Passenger tank locomotives, most suitable for such duties, were
few: most of them were Prussian classes T11 and T12 (in PKP service OKi1 and OKi2, respectively) plus several
Austro-Hungarian engines, but their combined number was only about 150 and
many of them were weak and obsolete. Due to lack of suitable engines, it was
a typical practice to use heavier passenger or even freight machines instead,
but this was certainly an interim measure. There was thus a need for a light,
fast passenger tank locomotive that could also be used with local trains.
Initially it was intended to build an improved version of successful Saxon
class XIV HT, which was designed specifically for suburban traffic (eleven
served with PKP as class OKl101),
but it was ultimately considered too weak and obsolescent. A decision was
thus taken to design an entirely new and modern locomotive, retaining only
the axle arrangement of the Saxon engine. The task was entrusted to the Cegielski company of Poznań
(HCP); their design was approved by
PKP in 1927 and accepted as class
OKl27. First five examples were supplied during the next year and production
lasted until 1933, when 122 locomotives had been built, all by HCP. This total included fifteen
engines delivered in 1929, thirty in 1930, twenty in 1931, 41 in 1932 and
eleven in 1933. Despite moderate, the orders for OKl27s were very important
for the company, as they helped to keep the factory busy during the Great
Crisis. Several
modifications were progressively introduced, as new engine was initially not
entirely satisfactory. After initial experience with Tr21 and Ty23, which
were prone to derailing, small idlers – only 860 mm in diameter – were used,
but no substantial improvement resulted. Adams idle axle was certainly not a
modern design feature at that time. Modification of truck springs gave some
improvement, but running remained somehow uneasy above 50 km/h; this,
however, was not a particular shortcoming, as the machine was not intended
for very high speeds. Another interesting feature was the introduction of
variable-length suspension levers which facilitated easy adjustment of
maximum axle load from 16 to 17.5 tonnes. In
examples from OKl27-21 onwards, due to fractures of side sills, frame was
redesigned and strengthened, which resulted in slight increase of overall
length and weight. First machines (up to OKl27-70 inclusive) had water boxes
of unequal lengths: the right one was slightly shorter, to provide space for
the compressor. This was later eliminated, in order to balance mass
distribution. Boiler accessories were also progressively modified and
electric lighting supplanted petroleum headlights in 1930. As in some other
pre-war Polish locomotives, some new design features were also tested, but
not all of them eventually found widespread use. OKl27-112 (HCP
291/1933) was fitted with the Wysłouch-type valve
gear, which proved in general successful, but somewhat complex (like similar
Lentz valve gear in Germany, it was not widely adopted and further
development was abandoned). Several examples were fitted with makeshift smoke
lifters, but these were never standardized. First
machines entered service in 1929 in Upper Silesia. Most were, however,
directed to the Warsaw railway hub, with heavy suburban traffic. Eight examples
were used by the French-Polish Railway
Society for passenger traffic on the ‘Coal Trunk Line’. They soon earned
a reputation of good, reliable locomotives, well suited to fulfill demands
they had been designed for. Suburban traffic remained their prime domain for
a long time. In
1939 one engine of this type (possibly from the French-Polish Railway
Society fleet – service number is not known to me) was used with the
makeshift armored train ‘Smok Kaszubski’
in the defense of Gdynia. Seriously damaged by direct bomb hits on September
11, it was deliberately derailed two days later. After the cessation of
hostilities most OKl27s were taken over by the Germans. 107 of them were
impressed into DRG service.
Initially they retained their Polish service numbers. In 1941 they were
classed 7512-13 (service numbers 75 1201 through 1307). Fifteen
were captured by the Soviets, but probably only two (OKl27-55 and OKl27-90)
were converted to the 1524 mm track. All Soviet engines retained their
original designations (written in Russian script as OKЛ27) and service
numbers. Except from the above-mentioned two, all fell after Fall
Barbarossa into German hands and were impressed into DRG and 75 1308 through 1320. During 1944 and 1945, Soviet forces
captured seven OKl27s, which were later impressed into the NKPS
service and never returned. Some, possibly all, retained their DRG designations.
In 1945, four OKl27s were found in Hradec Králové
in Czechoslovakia. Three of them (OKl27-117, then DRG 75 1302, OKl27-32, then DRG
75 1228 and OKl27-53, then DRG 75
1249) were impressed into ČSD
service as class 358.0 and designated 358.0500, 358.0501 and 358.0502,
respectively; the fourth (OKl27-4, then DRG
75 1204) was not re-designated. Their service with ČSD was brief and in 1947 all were returned to Poland. Seven
OKl27s were found in Austria; all were taken over by Soviet authorities in
1947, but returned to PKP in a few
days. Fourteen engines taken over by DB saw little service, if any.
Together with hundreds of various untypical locomotives they were formally
written off on December 13, 1951. In all, after the war, 95 OKl27s were given
new PKP service numbers. Of these,
OKl27-20 (pre-war OKl27-49, DRG 75
1245) was badly damaged and saw no service, to be written off in 1954 and scrapped.
The above total number includes 27 engines that returned from Eastern Germany
between 1949 and 1955 together with a number of other ones, on the basis of a
mutual agreement. Most of these engines were in a very poor condition and
were not even given new PKP service
numbers. OKl27s were, however, an exception, as all were re-numbered and
restored in service. Ultimate fate of five engines remains unknown. At first,
these comparatively new, modern and valuable locomotives served mainly near
Warsaw and in the Upper Silesia. Later, with mounting supplies of TKt48s
(despite designation, they were designed for the same role!) and
electrification, which progressed rapidly in suburban areas, they were
scattered throughout the country. Rapid
withdrawal of this class began in early 70s. In 1972 PKP had ninety
OKl27s, but until 1975 their number fell to 74 and in 1979 there was only one (plus three more, OKl27-41, -63 and
-76, which served at the railway stock repair works in Łapy
until 1985). The last machine in the PKP
inventory, OKl27-10 (pre-war OKl27-25, DRG
75 1225, s/n 172/1930) was used for switching in Skierniewice
locomotive depot until December 1979 and is now plinthed
there. Three more locomotives of this class have survived, namely: -
OKl27-27 (pre-war OKl27-65, DRG 75 1254, s/n 227/1931) at Gdynia Grabówek
loco depot, -
OKl27-41 (pre-war OKl27-91, DRG 75 1278, s/n 270/1932) at Chabówka
rolling stock heritage park, -
OKl27-26 (pre-war OKl27-61, DRG 75 1253, s/n 223/1931), initially preserved at the Praga locomotive depot in Warsaw, finally found its way
to the Railway Museum. All
of them are in good condition, but none is operational. Unfortunately, at
least three withdrawn OKl27s were scrapped in the 1990s. It
should be noted that OKl27 was in fact the very first machine of entirely
Polish origin; all earlier classes built in Poland had either German (Ok22,
Ty23) or Austrian (Tr21, Os24) background. This certainly gives it a place in
history. Main technical data
1)
Adjusted from 16.0 to 17.5 tonnes
(from OKl27-21 onwards, 18.2 tonnes) by changing
suspension levers mounting. 2)
Up to OKl27-20 inclusive: overall length 12 613 mm,
weight empty 61 500 kg, in working order 80 800 kg, weight on drivers 51 800
kg. List of vehicles can be found here. References
and acknowledgments
-
Monographic article by Paweł
Terczyński (SK vol. 1/1998); -
www.parowozy.best.net
(website by Michał
‘Doctor’ Pawełczyk) -
AP, PPN, LP; -
www.psmk.org.pl. (entry
on OKl27 by Tomisław Czarnecki); -
monographic article by Tomisław
Czarnecki (SS
vol. 140 and 141); -
www.beitraege.lokomotive.de.
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