Pt1

 

Pt1_1

 

Photos of Polish Pt1s are extremely rare. I have two low-res pictures of engines in the DRG service: 39 072 (Krupp 770/1924)…

 

Pt1_2

 

… and 39 122 (Hanomag 10335/1924). Further details are lacking.

 

Pt1_3

 

39 001, DR, Borsig 10999/1922. This engine was withdrawn in May 1968. Photo from my collection.

 

 

39 230 (MBG 2308/1925) on static display at the Deutsche Dampflokmuseum in Neuenmarkt; photo taken on May 1, 2014.

 

 

39 230 again, this time photographed in Bochum-Dahlhausen on October 5, 1985, by someone who wishes to be known as MPW57. Source: www.de.wikipedia.org.

Prussian passenger locomotive P8 appeared in 1906 and despite initial problems, mainly concerning running qualities, proved extremely successful. Production continued until 1928 (in fact, last license-built Romanian engines of this type were delivered from Reşiţa in 1940!) and almost 4,000 examples were built. P8 was a modern engine, running on superheated steam, capable of hauling even light express trains. It remained in service in some countries (including Poland) until early 1980s.

After WWI Prussian state railways KPEV were forced to transfer large number of engines to several foreign railway managements, as a part of war reparations. P8s, comparatively new and enjoying a good opinion, were a desirable booty. In order to make up for this loss, design work on a potential successor started at Borsig in 1919. Rather than producing an improved P8 (which was developed by Hanomag into Ok22 for PKP, later to be built by Fablok), a completely new engine was designed. One has an impression that it was the designers’ will to change as much as could be changed – even the basic layout. Axle arrangement was changed from 2-3-0 to 1-4-1, bar frame was used, Belpaire firebox was introduced and three-cylinder single-expansion steam engine replaced the two-cylinder one, to list only the fundamental changes. In fact, new engine owed all these features, apart from the axle arrangement, to the G12 freighter, which appeared in 1917 and itself was a development of a locomotive designed by Henschel for Turkish railways. Adaptation of the Belpaire firebox posed some problems, as there was insufficient space above the drivers, much larger in diameter than in the G12. This resulted in a complex grate form, with double curves in both horizontal and vertical directions; maintenance was troublesome and such layout was never repeated in any engine designed for German railways.

Post-war problems in Germany resulted in comparatively slow development and prototype was completed by Borsig only in April 1922. New engine was accepted by KPEV as class P10 and ordered in quantity, but in fact only few examples had been delivered with Prussian service numbers, as all railways of German Länden were merged into DRG. Production for DRG (classed 390-2) lasted until 1927 and totaled 260 engines from Borsig, Hanomag, Henschel, Linke-Hofmann and MBG Karlsruhe. They earned themselves a good reputation and often hauled light express trains, even in mountain areas – at least where their comparatively high axle load of 19.4 tonnes made it possible. Compared to their predecessors, they were – apart from the above-mentioned design differences – much more powerful, but heavier by over forty percent. Increase of boiler pressure from 12 to 14 bar contributed to improved efficiency.

P10 and G12 marked a transition between Prussian engines and DRG normalized types; it should be kept in mind, however, that the former was in fact not developed further, as it was the case with G12. With general speed increase in passenger traffic in the 1930s, stress was put on express engines, but all of them (apart from classes 06 and experimental class 1910, which both remained at the prototype stage) had three driven axles. Classes 23 and 24, built in small numbers, were much lighter and were basically intended for local traffic.

After WWII most engines of this type were divided between DB (154) and DR (88). Few served shortly with SNCF (one), SNCB (one, service number 67.001) and ÖBB (two), to be transferred to DB in  late 1940s. Four engines were either written off before 1945 or information on them is lacking. The only other recipient of this class was PKP, which received eleven examples. Probably due to their comparatively high power, they were considered express engines and hence classed Pt1, although their diameter of drivers (the same as in P8, in Poland known as Ok1) qualified them as passenger ones. Two (Pt1-9, ex 39 174, Linke-Hofmann 2912/1924, and Pt1-11, ex 39 217, Henschel 20272/1924) were written off in 1947. The remaining nine served until 1955, when they were exchanged with DR for pre-war Polish engines. Transfers were completed in early 1956. Due to comparatively short service with PKP, little is known about it and photographs are scarce.

Last engines of this type were withdrawn from service with DB in January 1967 and formally written off in July. With DR, their service lasted until 1979. 85 engines from the DR fleet were rebuilt between 1958 and 1961 with new, more typical boilers and feedwater heaters. They were re-designated class 22 and given new service numbers. In 1970 they were re-classed again (class 39, numbers as in class 22 but with first digit ‘1’ added). At least two engines of this type have been preserved in Germany: 39 184 (Linke-Hofmann 2922/1924) at the LHB museum in Salzgitter and 39 230 (MBG 2308/1925) at the Deutsche Dampflokmuseum, Neuenmarkt-Oberfranken.

 


Main technical data

 

No.

Parameter

Unit

Value

1.

Years of manufacture

-

1922 – 1927

2.

Total built / used in Poland

-

260 / 111)

3.

Tender class

-

32D2

4.

Axle arrangement

-

1-4-1

5.

Design maximum speed

km/h

110

6.

Cylinder bore

mm

3 X 520

7.

Piston stroke

mm

660

8.

Engine rating

kW/hp

1192 / 1620

9.

Tractive effort

kG

10.

Boiler pressure

MPa

1.43

11.

Grate dimensions

m X m

4.07 m2

12.

Firebox heating surface

m2

17.51

13.

Distance between tube plates

mm

5 800

14.

Number of flue tubes

-

138

15.

Heating surface of flue tubes

m2

17.51

16.

Number of smoke tubes

-

34

17.

Heating surface of smoke tubes

m2

77.2

18.

Evaporating surface, total

m2

218.16

19.

Superheater heating surface

m2

82.0

20.

Diameter of drivers

mm

1750

21.

Diameter of idlers front/rear

mm

1000 / 1100

22.

Total weight, empty

kg

23.

Total weight, working order

kg

110 400

24.

Weight on drivers, working order

kg

75 700

25.

Weight with tender, empty

kg

26.

Weight with tender, working order

kg

185 900

27.

Maximum axle load

T

19.4

28.

Axle base (with tender)

mm

19 300

29.

Overall length (with tender)

mm

22 980

30.

Brake type

-

Knorr

 

1)      Including two withdrawn in 1947.

 

References and acknowledgments

 

Due to short service of this class with PKP, information is scarce and photos are extremely rare. Statistics, as usually, have been taken from the Ingo Hütter’s database (available at www.lokomotive.de).