Pu29

 

Pu29_1

 

Pu29-3 (HCP 200/1931), Kościerzyna loco depot, August 2000.

 

Pu29_2

 

The same machine, February 5, 2003 – note missing ash-pan side boxes.

 

Pu29_3

 

The same machine, February 5, 2003 – note flat smoke-box door.

 

Pu29_sc

 

Pu29 – drawing by M.Ćwikła (from SK vol.4/2000).

 

Pu29_4

 

Still bearing the Pu29-1 service number, the sole surviving example was photographed in Bydgoszcz in June 1964. Photo from my collection.

 

 

Factory photo of the Pu29-1, date unknown. Source: National Digital Archives via www.pl.wikipedia.org.

 

 

In late 1920s express locomotives in the PKP service represented a motley collection of engines, almost exclusively of German or Austrian origin. Most of them were obsolete. Older machines, such as Prussian classes S3, S4, S5 and S6 or Austrian 108 and 308, had only two driven axles. Austrian classes 210 and 310, with three driven axles, were suitable only for light trains. Even Prussian class S10 locomotives, considered superior to previously mentioned ones, were becoming too weak. Polish Os24s and Ok22s, basically intended for passenger traffic, typically hauled express trains, but certainly this was an interim measure. There was a need for a powerful, fast engine for heavy (and prestigious) express trains, so in early 1929 two prototypes were ordered, one from the Cegielski works (HCP) of Poznań and one from Fablok.

All above-mentioned express engines of foreign origin had two-axle lead trucks and this was then considered in Europe almost a must for a fast locomotive. Four driven axles were mandatory, in order keep axle load within acceptable limits. After much discussion it was decided to adopt the 2-4-1 axle arrangement for one prototype and 1-4-1 for the other, in order to compare their characteristics in service. The former layout was quite widespread, although the first 2-4-1 ever was a modest narrow-gauge tank engine, built by Dubs of Glasgow for Natal Government Railway (100 examples delivered between 1888 and 1900). In the USA, 2201 such machines were built between 1911 and 1948 (according to Guide to North American Steam Locomotives by George H. Drury), used for passenger as well as for fast freight trains; the heaviest of them exceeded 192 tonnes. They were known as Mountains or Mohawks. Engines with this axle arrangement, which combined good running qualities and high tractive effort at moderate axle load, were also used in Europe (with a notable exception of Germany) – mainly in France and Spain.

Three prototypes of the 2-4-1 locomotive, designated Pu29 with PKP, were built by HCP in 1931 (serial numbers 198 through 200); new large four-axle tenders, class 32D29, the largest built in Poland before WWII, were designed for these engines. First test runs took place in September 1931. Performance turned out to be good: with nineteen four-axle coaches, weighting 818 tonnes in all, 105 km/h could be maintained and maximum speed reached 112 km/h. Due to the axle arrangement, running was very smooth. Footplate crews praised good visibility and easy access to the running gear and brakes. Fuel consumption, despite live-steam injectors of excessive output, was comparatively low. There were only few minor shortcomings, easy to rectify. The machine looked impressive and powerful, measuring almost 25 metres with tender. This length, however, eventually turned out to be crucial for the final fate of this otherwise very successful design. Axle base was over 21 metres and only few turntables in Poland could accept machines exceeding 20 metres. Pu29 was simply too long. With the appearance of the 1-4-1 contender, the Pt31 from Fablok, the choice obviously fell on the latter type – only slightly smaller and less powerful, but due to axle base reduced by just 960 mm much more handy. It should be noted that two competing prototypes, although built by different companies, had much in common, including steam engine and drivers; steam parameters were also the same.

All three Pu29s remained in use until September 1939, mainly in northern Poland. Pu29-3 was captured by the Germans and impressed into DRG service as 12 201. Both remaining examples were taken over by the Soviets. Pu29-1 fell into German hands at the Eastern Front, to be given DRG service number 12 202 (this locomotive remained with DB and was written off in May 1952). Pu29-2 was converted for the 1524 mm track and retained its original designation, written in Russian script (ПУ29-2).  Its ultimate fate remains unknown; according to some Russian sources, it was written off in 1958 (information from PNPP). After WWII, only the 12 201, found in Czechoslovakia, returned to Poland and was restored in service in 1950 as Pu29-1 (initially it was erroneously identified as a Pt31 and numbered Pt31-46). After twenty years in service, again mainly in Northern Poland, she was withdrawn in March 1970. It was decided to keep this engine as a museum exhibit, but eight years passed before this could be effected. In the meantime she was slightly damaged and subsequent restoration – apart from fitting plates with the pre-war service number Pu29-3 – did not bring her up to its original condition. In particular, convex smoke-box door with the central lock has been replaced by a flat one and ash pan side-boxes are missing (removed probably in early 50s). This engine was transferred to the Railway Museum in Warsaw in 1978.  Refurbished externally in 1993 at the Zajączkowo Tczewskie depot, she was transferred to the former depot in Kościerzyna as a static exhibit. In December 2012 she was brought back to Warsaw.

It is worth reminding here that Pu29 was the largest and heaviest Polish steam locomotive ever built for domestic service: even the impressive and powerful Ty51 was lighter by almost four tonnes (in working order) and, of course, considerably shorter. 

 


 

Main technical data

 

No.

Parameter

Unit

Value

1.

Years of manufacture

-

1931

2.

Total built / used in Poland

-

3 / 3

3.

Tender class

-

32D29

4.

Axle arrangement

-

2-4-1

5.

Design maximum speed

km/h

1001)

6.

Cylinder bore

mm

2 X 630

7.

Piston stroke

mm

700

8.

Engine rating

kW/hp

1334 / 1820

9.

Tractive effort

kG

13 500

10.

Boiler pressure

MPa

1.53

11.

Grate dimensions

m X m

2.78 X 1.78

12.

Firebox heating surface

m2

18.5

13.

Distance between tube plates

mm

6 500

14.

Number of flue tubes

-

103

15.

Heating surface of flue tubes

m2

132,0

16.

Number of smoke tubes

-

26

17.

Heating surface of smoke tubes

m2

80.0

18.

Evaporating surface, total

m2

230.5

19.

Superheater heating surface

m2

86.8

20.

Diameter of drivers

mm

1850

21.

Diameter of idlers front/rear

mm

860 / 1200

22.

Total weight, empty

kg

102 800

23.

Total weight, working order

kg

113 800

24.

Weight on drivers, working order

kg

72 600

25.

Weight with tender, empty

kg

129 300

26.

Weight with tender, working order

kg

182 300

27.

Maximum axle load

T

18.5

28.

Axle base (with tender)

mm

21 195

29.

Overall length (with tender)

mm

24 595

30.

Brake type

-

West

 

1)   Some sources give 110 km/h

 

References and acknowledgments

 

-       Monographic article by Paweł Terczyński (SK vol. 4/2000);

-       PNPP, LP.