OKm11

 

OKm11_1

 

629.01 from the Südbahn fleet (StEG 3883/1913) has been preserved at the Heizhaus Strasshof, Austria; photo taken on June 20, 2009.

 

OKm11_2

 

 Late production 354.1207, ČSD (Škoda 858/1937), location and date unknown (obviousl after the war!). Postcard from my collection.

 

OKm11_4

 

Two more 354.1s on postcards from my collection: 354.1160 (Škoda 628/1930), still in service, Kraliky, June 18, 1977…

 

OKm11_3

 

…and 354.195 (PČM 1055/1925), photographed near Vižina on September 18, 2004, with a special train.

 

 

Former BBÖ 629.43, later ÖBB 77.28, Krauss Linz 1183/1920, photographed in Gmunden on May 1, 2008. Photo by Ernst Wolf (from my collection).

 

 

77.250, ÖBB (pre-war 629.65, Krauss Linz 1430/1927), Wien Ost station, August 17, 1986. This locomotive later ran in Liechtenstein with special trains. Photo from my collection.

 

 

629.01, Südbahn, StEG 3883/1913, photographed at the Heizhaus Strasshof on April 30, 2000. Photo by Herbert Orther (www.commons.wikimedia.org).

The 2-3-1 axle arrangement, known as Pacific, was very popular in Europe and chosen by many companies for fast, if not very heavy, express locomotives. The most popular record-breaking streamlined engines, A4 ‘Mallard’ (LNER) and 03 001 (DRG), were Pacifics; so was Polish Pm36, perhaps the best known PKP steam locomotive. Austrian railways were a notable exception: their only Pacific was class 629, a tank engine intended for passenger and light express traffic.

Class 629 was conceived as a successor to earlier class 229 (1-3-1 axle arrangement, PKP class OKl12) and, after some discussion concerning axle loads, two-axle lead truck was introduced. This was in fact intended not to improve running qualities, but rather to avoid excessive front axle load with longer and heavier boiler. Another important modification was introduction of steam superheating and single-expansion engine. First fifteen engines of this type were ordered by Südbahn, delivered between 1913 and 1915 and numbered 629.01 through 15. They turned out to be a successful design; their maximum speed was 85 km/h, but they reportedly attained 110 km/h (presumably running smokebox first) with no particular problems. Further orders came from KkStB (Kaiserlich-königliche österreichische Staatsbahnen), for twenty-five examples: these were numbered 629.01 through 25, so after Südbahn had been incorporated into KkStB, their engines were re-numbered 629.101 through 115 to avoid confusion. Of these forty locomotives, fifteen went to Czechoslovakia and post-war BBÖ were left with the rest (including all from Südbahn). Production continued, further batches being delivered between 1920 and 1922 (629.26 through 55) and between 1926 and 1927 (629.56 through 80). Last five examples, numbered 629.500 through 504 and built in 1927, were fitted with Caprotti valve gears, which did not prove successful and were later replaced with conventional piston valves. Austrian locomotives were built by StEG, Wiener Neustadt and Krauss Linz. After the Anschluss they were taken over by DRG and given service numbers 77 201 through 265, 266 through 280 (former Südbahn engines) and 281 through 285 (class 629.5).

Class 629 found remarkable favor in Czechoslovakia. Apart from acquiring fifteen KkStB 629s, Czechoslovakian state railways ČSD placed further orders. All these engines were later re-classed 354.1. Production continued until 1941 and totaled 219 examples from Škoda (198), PČM (fifteen) and Breitfeld-Danĕk (six). Later batches featured numerous improvements and modifications, including two steam domes connected by a horizontal tube of large diameter (typical for many pre-war Austrian engines) and redesigned steam superheater. Five were fitted with Lentz valve gears; just as with their Austrian counterparts, this did not prove successful. Last fifteen examples were completed under German supervision for the railways of Protectorate (Böhmisch-Mährische Bahn, ten, 1940) and Slovakia (five, 1941). They featured single steam domes and were the only variant fitted with smoke lifters. 49 354.1s were impressed into DRG as 77 301 through 349; further five (77 350 through 354) were renumbered only formally and leased to BMB. All were returned after the war. ČSD also obtained two ex-BBÖ engines (354.1500 and 354.1501); five went to Yugoslavia and were impressed into JDŽ state railways as class 18.

No locomotives of this type were transferred to Polish state railways after WWI as a part of war reparations, but in 1921 ten brand-new 629s were ordered in Austria from Krauss Linz. Deliveries were completed in 1922 and these engines were classed OKm11. In accordance with their original assignments, they operated mainly in southern and south-eastern Poland, in conditions similar to those they had been designed for. In 1939 six OKm11s fell into Soviet hands, all becoming German booty in 1941. Apart from these, DRG took over three examples in 1939. Of these nine engines five were given DRG numbers 77 286 through 290 and four served with Ostbahn, probably with their original numbers. The fate of the OKm11-10 is unclear; according to LP, it was possibly handed over to Organisation Todt and designated OT 26, but confirmation is lacking. ITFR lists this engine (Krauss Linz 1289/1922) as being acquired by CFR after the war and impressed into service as 231.902; Polish service number, however, is not mentioned. All engines of this type operated by DRG were passed over to ÖBB after the war, to be returned to PKP shortly afterwards. Last were withdrawn in 1954.

Post-war service of these locomotives was comparatively long. In Austria last were withdrawn in 1976 and in Czechoslovakia in 1978. As many as eight have been preserved, in Austria (three, two operational), Czech Republic (two, one operational), Liechtenstein (one, operational), Slovakia (one) and Slovenia (one, plinthed).


Main technical data

 

No.

Parameter

Unit

Value

1.

Years of manufacture

-

1913 – 19411)

2.

Total built / used in Poland

-

3291) / 10

3.

Tender class

-

-

4.

Axle arrangement

-

2-3-1

5.

Design maximum speed

km/h

85

6.

Cylinder bore

mm

2 X 475

7.

Piston stroke

mm

720

8.

Engine rating

kW/hp

9.

Tractive effort

kG

10.

Boiler pressure

MPa

1.32

11.

Grate dimensions

m X m

2.70 m2

12.

Firebox heating surface

m2

12.2

13.

Distance between tube plates

mm

14.

Number of flue tubes

-

129

15.

Heating surface of flue tubes

m2

16.

Number of smoke tubes

-

21

17.

Heating surface of smoke tubes

m2

18.

Evaporating surface, total

m2

129.65

19.

Superheater heating surface

m2

33.75

20.

Diameter of drivers

mm

1 614

21.

Diameter of idlers front/rear

mm

1 034 / 1 034

22.

Total weight, empty

kg

43 200 / 45 0002)

23.

Total weight, working order

kg

80 200 / 83 8002)

24.

Weight on drivers, working order

kg

25.

Weight with tender, empty

kg

-

26.

Weight with tender, working order

kg

-

27.

Maximum axle load

T

28.

Axle base (with tender)

mm

9 590

29.

Overall length (with tender)

mm

13 345

30.

Brake type

-

Westinghouse

 

1)     Including production in Czechoslovakia.

2)     Depending on variant.

 

References and acknowledgments

 

-         LP, EZ, ITFR, EDÖ;

-         www.pl.wikipedia.org.