OKf100

 

Tk 11 (Škoda 751/1932), factory photo…

 

 

 …and second photo of the same engine. Both photos from Škoda archives via Toms Altbergs (many thanks!).

 

 

Side drawing of OKf100 by M.Ćwikła from SK vol.3/2002.

In late 1920s and early 1930s steam locomotive had to face the competition of motor cars and diesel railcars, especially in suburban traffic. This resulted in appearance of comparatively light and fast passenger tank engines, well suited for specific requirements of frequent stops and fast startups. One of them was class Tk of Lithuanian state railways Lietuvos Gelezinkeliai (LG), of which four examples were built by Czechoslovakian Škoda in 1932 (serial numbers 751 through 754). For these locomotives, a somehow exotic axle arrangement of 1-2-2 was chosen. While 2-2-1 was quite popular in Europe in late 19th and early 20th centuries, especially with express locomotives (e.g. Prussian classes S7, S8 and S9 or Austrian classes 108, 208 and 308), its reverse was employed only in several tank engines built for the railways of Bavaria, Palatinate and Alsace-Lorraine. In the USA this arrangement was quite popular with small locomotives designed for negotiating tight curves, usually of the Mason Bogie variety. 1-2-2 axle arrangement in a tank engine allowed for a spacious coal bunker and at the same time left ample space for the firebox.

Four Tks were assigned LG service numbers 11 through 14 and all were based in Kaunas, then the capital of Lithuania. They were modern engines for their time, with Knorr brakes, steam superheating and water cleaners. Apart from axle arrangement they could be easily distinguished by smoke lifters that were attached to the front edges of water tanks, extended to the smokebox. After the annexation of Lithuania in 1940 they were taken over by NKPS, later falling into German hands. No.11 and No.13 saw little use, if any, and were scrapped a few years after the war. No.12 was transferred to a German industrial establishment and finally scrapped in Strassfurt in 1953. No.14 (Škoda 754/1932) was first transferred to the Škirotawa depot near Riga, Latvia. In 1942 it was taken to Austria and assigned to the Wien-Hütteldorf depot. For some unknown reason it was designated Pk 14; according to the article published in SK (see References) this was probably due to the fact that, according to Latvian system, capital P denoted light freight locomotives. In 1945 this engine was captured by the Soviets and became TPk 14, where ‘T’ stood for ‘trofyeinyi’, or booty. Probably found to be of little use for its new owners and not worth re-gauging, it was handed over to PKP and initially erroneously designated TKp 14. Later its designation was changed to OKf100-1. As with several other PKP classes (TKh100, TKi100 etc.), number ‘100’ in the designation indicated that this class is to include various engines, mainly from private railways and industry, the axle arrangement being their sole common feature. However, OKf100-1 became the single representative of this class. It was assigned to the Katowice regional management and immediately sent to a railway stock repair works in Wrocław. Due to poor overall condition it was never restored in service and finally scrapped in 1950. Its boiler remained in use in Wrocław until about 1975.


Main technical data

 

No.

Parameter

Unit

Value

1.

Years of manufacture

-

1932

2.

Total built / used in Poland

-

4 / 1

3.

Tender class

-

-

4.

Axle arrangement

-

1-2-2

5.

Design maximum speed

km/h

90

6.

Cylinder bore

mm

2 ´ 500

7.

Piston stroke

mm

630

8.

Engine rating

kW/hp

 

9.

Tractive effort

kG

 

10.

Boiler pressure

MPa

1.43

11.

Grate dimensions

m X m

2.04 m2

12.

Firebox heating surface

m2

9.34

13.

Distance between tube plates

mm

 

14.

Number of flue tubes

-

 

15.

Heating surface of flue tubes

m2

 

16.

Number of smoke tubes

-

 

17.

Heating surface of smoke tubes

m2

 

18.

Evaporating surface, total

m2

105.14

19.

Superheater heating surface

m2

38.5

20.

Diameter of drivers

mm

1 600

21.

Diameter of idlers front/rear

mm

1 000 / 1 000

22.

Total weight, empty

kg

59 600

23.

Total weight, working order

kg

81 600

24.

Weight on drivers, working order

kg

35 000

25.

Weight with tender, empty

kg

-

26.

Weight with tender, working order

kg

-

27.

Maximum axle load

T

17.5

28.

Axle base (with tender)

mm

9 600

29.

Overall length (with tender)

mm

12 812

30.

Brake type

-

Knorr

 

References and acknowledgments

 

-         Lietuvos Geležinkelių Garvežiai 1919-1940 m. / Steam Locomotives of Lithuanian Railways 1919-1940 by Toms Altbergs (Zidex, Lithuania, 2012);

-         article on Lithuanian and Latvian locomotives in the PKP service by Tomasz Roszak (SK vol. 3/2002);

-         www.pospichal.net/lokstatistik (website by Josef Pospichal);

-         www.pl.wikipedia.org.