TKh2

TKh12-2, photographed at the Jaworzyna Śląska depot on August 4, 2004.

The same engine, photographed on May 1, 2006; in the meantime the depot has become the Industry and Railway Museum. With the Tr7-3 in the background, TKh2-2 looks diminutive.

Class 89⁷⁸ side drawing from TB vol.2; © Lokomotiv-Revue.

Three-axle switcher, ordered by Prussian state railways KPEV in 1879 and later standardized as class T3, was followed by a machine similar in layout, but heavier and substantially stronger. It appeared in 1883 and featured drivers increased in diameter from 1100 to 1330 mm, larger cylinders (bore/stroke 430/600 mm instead of 350/550 mm) and coal-box located behind the cab. Axle load was increased from 12 to almost 15 tonnes and tractive effort was higher by over thirty percent. Steam pressure, initially set at 10 bars, was soon increased to 12 bars. New engine, later standardized as T7, was intended mainly as a switcher for large freight stations in industrial regions, like Upper Silesia, Rheinland, Ruhr and Saarland.

T7 remained in production until 1893 and, despite deliveries from eight manufacturers (Borsig, Grafenstaden, Hanomag, Henschel, Hohenzollern, Union, Vulcan and Wöhlert) total output was quite modest, amounting to 374 examples for KPEV (which received 1345 T3s between 1882 and 1910). Further 65 examples were built for various other operators. Although more powerful than T3, T7 was in fact less versatile and its axle load was too high for many secondary lines and Kleinbahnen (local railways) with weak tracks. Production on a small scale continued after WWI (according to some sources, until 1925) for various private operators, which received 28 engines, differing only in minor details. This gives the grand total of 467 examples.

After WWI, newly-created Deutsche Reichsbahn Gesellschaft (DRG) were not particularly eager to keep T7s in service: only 68 examples were kept, classed 89⁷⁸. One more, from Bremer Hafenbahnen, followed in 1930 and was impressed into service as 89 7869. DRG almost completely got rid of these engines before 1930, as more modern and powerful successors were at hand. Few went to various private operators and industry. The above-mentioned 89 7869 (Vulcan 1513/1895), the last to be withdrawn from the DRG service, was sold to Kreis Oldenburger Eisenbahn in December 1932. Taken back by DRG in 1941, it was later captured by the Soviets and written off in 1951. 89 7830 (Union 546/1890), sold to a private operator, was withdrawn in 1960 as the last engine of this type in service in Germany.

Exact number of T7s obtained by Polish railways after WWI is not known, but most probably they numbered 30 examples (older Polish sources give 27). They were classed TKh2. Few details on their service are available. LP, a most competent source, lists their serials and KPEV service numbers, but PKP numbers of individual examples are not known. All these engines were withdrawn from PKP in early 1930s and some went to industry. There is only one bright point in this dull and uninspiring picture. KPEV Kattowitz 6945 (Union 534/1890), which became TKh2-12, was transferred to the Kazimierz Juliusz colliery in Sosnowiec, survived WWII there and remained in use into 1960s, as probably the last engine of this type in the world. Given the fact that many locomotives more important for Polish railway history can now be seen only in photos, it is somehow surprising that this very engine has been preserved. Transferred to the Railway Museum in Warsaw, it was later taken to the Industry and Railway Museum in Jaworzyna Śląska and can now be seen there with its original PKP service number. According to available sources, this is the only surviving T7.

Main technical data

No.	Parameter	Unit	Value
1.	Years of manufacture	-	1881 – 1893^1)
2.	Total built / used in Poland	-	467 / 30^2)
3.	Tender class	-	-
4.	Axle arrangement	-	0-3-0
5.	Design maximum speed	km/h	45
6.	Cylinder bore	mm	2 X 430
7.	Piston stroke	mm	630
8.	Engine rating	kW/hp
9.	Tractive effort	kG	8 300
10.	Boiler pressure	MPa	1.22
11.	Grate dimensions	m X m	1.32 m^2
12.	Firebox heating surface	m^2
13.	Distance between tube plates	mm
14.	Number of flue tubes	-
15.	Heating surface of flue tubes	m^2
16.	Number of smoke tubes	-	-
17.	Heating surface of smoke tubes	m^2	-
18.	Evaporating surface, total	m^2	96.18
19.	Superheater heating surface	m^2	-
20.	Diameter of drivers	mm	1330
21.	Diameter of idlers front/rear	mm	- / -
22.	Total weight, empty	kg
23.	Total weight, working order	kg	41 900
24.	Weight on drivers, working order	kg	41 900
25.	Weight with tender, empty	kg	-
26.	Weight with tender, working order	kg	-
27.	Maximum axle load	T	14.0
28.	Axle base (with tender)	mm	3 400
29.	Overall length (with tender)	mm	9 560
30.	Brake type	-	hand / Westinghouse

1) Production continued after WWI (until 1925?).

2) Approximate number; no detailed data.

References and acknowledgments

Description can be found in TB vol.2. Few data on Polish TKh2s is available; short account and statistics can be found in LP.