Oc11

KFNB IIIb1 No. 115 ‘Titan’ (StEG 821/1868), later kkStB 121.05. Factory photo, date unknown. After the war this locomotive was taken over by PKP and withdrawn before 1927. Source: www.commons.wikimedia.org.

After WWI newly-formed Polish state railways PKP took over locomotives of German, Austro-Hungarian and Russian origins. In general, engines from kaiserlich-königliche Staatsbahnen (kkStB) belonged to comparatively many classes, often represented by single examples. Many of them were originally built for private operators that were later absorbed by kkStB. When new PKP class designation system was introduced in 1925, many of them had already disappeared from the company’s rosters. Assignment of these designation to ex-kkStB classes is in many cases still subject to dispute, as original documentation is not available and only indirect sources can be used.

According to LP, kkStB classes 24, 107 and 121 were re-classed Oc11, Oc12 and Oc17. Other sources indicate that probably class 24 became Oc12 and class 107 became Oc17. That leaves Oc11 as the most probable candidate for class 121. Confirmation by reliable sources is, however, lacking.

Between 1867 and 1873 Kaiser Ferdinands-Nordbahn (KFNB) took delivery of 52 passenger locomotives with outer frame and 1-2-0 axle arrangement, classed IIIb. Most of them (38) were built by StEG, the rest coming from Sigl (Wiener Neustadt works, eight) and Hanomag (six). They were numbered 110 through 161 and all were given individual names. Examples numbered 110 through 133 (first batch from StEG) had boiler pressure of 8.5 bar. Since 1871 modernized boiler was fitted, with pressure increased to 10 bar. Some earlier examples were later re-boilered. Modernized locomotives were later referred to as class IIIb2, the original version being re-classed IIIb1. KFNB was nationalized in 1909; three examples had been withdrawn earlier and the rest were impressed into state railways kkStB and re-numbered 121.01 through 49. Sixteen were written off between 1912 and 1918. The rest were divided between Austrian state railways BBÖ (27) and PKP (six). The last Austrian engine in service, 121.14 (ex KFNB No. 124 ‘Lundenburg’, StEG 954/1869) was written off in June 1926. As already mentioned, PKP class Oc11 assignment is not confirmed; possibly it was only formal, as all engines of this type were written off before 1927. No details on their service is available. Not a single locomotive of this type has been preserved.

Main technical data

No.	Parameter	Unit	Value
1.	Years of manufacture	-	1867 – 1873
2.	Total built / used in Poland	-	52 / 6
3.	Tender class	-
4.	Axle arrangement	-	1-2-0
5.	Design maximum speed	km/h	70
6.	Cylinder bore	mm	2 x 395
7.	Piston stroke	mm	632
8.	Engine rating	kW/KM
9.	Tractive effort	kG
10.	Boiler pressure	MPa	0.87 / 1.02^1)
11.	Grate dimensions	m x m	1.70 m^2
12.	Firebox heating surface	m^2	8.0 / 7.4^1) / 7.2^2)
13.	Distance between tube plates	mm	4 350
14.	Number of flue tubes	-	164 / 165^1) / 160^2)
15.	Heating surface of flue tubes	m^2	114.7 / 118.5^1) / 115.7^2)
16.	Number of smoke tubes	-	-
17.	Heating surface of smoke tubes	m^2	-
18.	Evaporating surface, total	m^2	122.7 / 125.9^1) / 122.9^2)
19.	Superheater heating surface	m^2	-
20.	Diameter of drivers	mm	1 480
21.	Diameter of idlers front/rear	mm	1 085 / -
22.	Total weight, empty	kg	27 750 / 30 000^1)
23.	Total weight, working order	kg	30 300 / 34 000^1)
24.	Weight on drivers, working order	kg	20 700 / 23 500^1)
25.	Weight with tender, empty	kg
26.	Weight with tender, working order	kg
27.	Maximum axle load	T
28.	Axle base (with tender)	mm	10 465
29.	Overall length (with tender)	mm	14 520
30.	Brake type	-

1) Data after re-boilering.

2) 121.04, 121.14 and 121.19 after re-boilering.

References and acknowledgments

- LP, KT vol. 1, LAÖ;

- www.de.wikipedia.org.