OKl11

The sole surviving 175.817 (ex kkStB 29.22), BMMF 432/1912, photographed at the Heizhaus Strasshof on June 20, 2009. It’s not easy to take a better photo…

… but it used to be in the past. Photo taken by Herbert Ortner on April 4, 1999 (source: www.commons.wikimedia.org).

OKl11 side drawing by M. Ćwikła; source: SK vol.3/2003.

KkStB 29.01 (BMMF 411/1912), location and date unknown – probably a factory photo. After 1918 this locomotive became OKl11-1; captured by Germans and re-numbered 75 827, it was then taken over by ČSD and withdrawn in 1950s. Source: Dle Lokomotive August 1913.

ÖBB 175.808 (ex kkStB 29.12, then DRG 75 808), BMMF 422/1912, photographed in Villach, Austria, in 1952. This engine was withdrawn in June 1959. Source: www.commons.wikimedia.org.

Between 1904 and 1918 Austro-Hungarian state railways KkStB (Kaiserlich-königliche österreichische Staatsbahnen) received 239 very successful class 229 tank locomotives for passenger and light express trains. They featured 1-3-1 axle arrangement, were fitted with compound engines and ran on saturated steam. Twenty-five very similar locomotives were built for other railway managements; furthermore, seventeen earlier class 129 engines (1-3-0 axle arrangement) were later rebuilt to this standard. After WWII, class 229 served with PKP as OKl12 (described under a separate entry).

Early 20^th century saw the introduction of steam superheating, as a means to improve engine efficiency and economy. A variant of class 229 running on superheated steam was thus designed and emerged in 1912 as class 29. This designation was used for the second time, after a batch of fifteen engines built for Kronprinz Rudolfs-Bahn by Sigl between 1868 and 1869 – surviving old engines were duly re-classed 929. Boiler was fitted with eighteen smoke tubes, high-pressure cylinder was increased in diameter from 420 to 450 mm and piston valves replaced slide ones. In order to keep axle load below 14.5 tonnes, water boxes had to be shortened and rear part of the frame was increased in length by 250 mm. Class 29, however, was not as successful as its predecessor. Coal and water consumption were lower indeed, but due to evaporating surface reduced by almost nine percent boiler capacity was sometimes insufficient. Tractive effort was marginally lower. A batch of 36 examples (three from WLF and 33 from BMMF) was delivered in 1912 and then production shifted back to well-proven 229.

After WWI Austrian state railways BBÖ were left with 26 examples of class 29. After Anschluss all were taken over by DRG and re-numbered 75 801 through 826. Returned after the war, they became ÖBB class 175; last survived in service until 1962. 29.18 went to JDŽ and was designated 116-017 (in 1941 it was captured by Germans and became 75 836). The remaining nine 29s were taken over by PKP; after 1925 they were classed OKl11. Initially assigned to the Kraków regional management, in mid-1930 all were transferred to Katowice, to serve with local passenger trains. In 1939 all OKl11s were captured by Germans and impressed into DRG service in Austria as 75 827 through 835. Immediately after the war two were in Hungary and one in the Soviet Union. In 1948 three returned from Austria; re-numbered OKl11-1 through -3, they were impressed into PKP service, but one was withdrawn in 1950 and the remaining two three years later. In 1953 two more followed from Hungary (one from MÁV and one from GySEV), but, despite being assigned PKP service numbers OKl11-4 and OKl11-5, they went directly to industry (collieries). One of them remained in use until 1961. Unfortunately, none has been preserved.

Only one locomotive of this type has survived until today. KkStB 29.22 (BMMF 432/1912), later DRG 75 817, then ÖBB 175.817, withdrawn from use in 1956, can be seen on static display in Austria at the Heizhaus Strasshof.

Main technical data

No.	Parameter	Unit	Value
1.	Years of manufacture	-	1912
2.	Total built / used in Poland	-	36/ 9
3.	Tender class	-	-
4.	Axle arrangement	-	1-3-1
5.	Design maximum speed	km/h	80
6.	Cylinder bore	mm	450 / 650
7.	Piston stroke	mm	720
8.	Engine rating	kW/hp
9.	Tractive effort	kG	7 000
10.	Boiler pressure	MPa	1.43
11.	Grate dimensions	m x m	2.0 m^2
12.	Firebox heating surface	m^2
13.	Distance between tube plates	mm	3 500
14.	Number of flue tubes	-
15.	Heating surface of flue tubes	m^2
16.	Number of smoke tubes	-	18
17.	Heating surface of smoke tubes	m^2
18.	Evaporating surface, total	m^2	88.1
19.	Superheater heating surface	m^2	18.8
20.	Diameter of drivers	mm	1614^1)
21.	Diameter of idlers front/rear	mm	870 / 870
22.	Total weight, empty	kg
23.	Total weight, working order	kg	68 300
24.	Weight on drivers, working order	kg	43 200
25.	Weight with tender, empty	kg	-
26.	Weight with tender, working order	kg	-
27.	Maximum axle load	T	14.4
28.	Axle base (with tender)	mm	8 000
29.	Overall length (with tender)	mm	12 016
30.	Brake type	-	Hardy

1) 1574 mm according to Austrian standards (medium-degree flange wear).

List of vehicles can be found here.

References and acknowledgments

- Monographic article by Paweł Terczyński (SK vol. 3/2003);

- EZ, LP, EDÖ;

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

- http://republika.pl/derela (website by Michał Derela – information on armored locomotives).