OKl27
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OKl27-41 (HCP
270/1932), preserved at Chabowka loco heritage park, photographed in June
2001.
OKl27-26 (HCP
223/1931), displayed at the
Another picture of this engine: September 19, 2010.
This OKl27-10 (HCP
172/1930), owned by PSMK
(railway fans society), is 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 |
Very
few locomotives acquired by PKP
after WWI could be used on suburban lines; this service demanded 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 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). Soon, however, a decision was taken to design an entirely
new and modern machine, retaining only the axle arrangement of the Saxon
engine. The task was entrusted to the Cegielski factory of Poznań (HCP); their design was approved by PKP in 1927 and accepted as class
OKl27. First four examples were supplied during the next year and production
lasted until 1933, when 122 machines had been built, all by HCP. Despite moderate output (from 16
in 1929 to 30 in 1930 and 1932), the order for OKl27s 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 and the problem was finally solved by
replacing in 1930 Adams idle axle with the Krauss-Helmholtz truck. Running,
however, remained somehow uneasy above 50 km/h, but this was not a particular
shortcoming, as the machine was not intended for 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. 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 as class 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. They retained
their original designation (written in Russian script as OKЛ27) and
service numbers. The remaining thirteen fell after Fall Barbarossa into
German hands and became 75 1308 through 1320. During 1944 and 1945, Soviet
forces captured eleven OKl27s, which were later impressed into the NKPS
service and never returned. They probably 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 returned in
1947. A number of engines (fourteen?), taken over by DB, saw little
service, if any, and were written off in 1952. In all, after the war, 95
OKl27s were given new PKP service
numbers. Of these, OKl27-20 was badly damaged and was scrapped in late 40s.
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 used by 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. 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).
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