History

The Prussian Class T 11 were passenger tank locomotive

Tank locomotive

A tank locomotive or tank engine is a steam locomotive that carries its water in one or more on-board water tanks, instead of pulling it behind it in a tender. It will most likely also have some kind of bunker to hold the fuel. There are several different types of tank locomotive dependent upon...

s in the service of the Prussian state railways

Prussian state railways

The term Prussian state railways encompasses those railway organisations that were owned or managed by the State of Prussia...

 that were intended for duties on the Berlin Stadtbahn. To that end 470 engines of this type were procured between 1903 and 1910. Like the superheated locomotive, the Prussian T 12

Prussian T 12

The Prussian Class T 12 is an early, German, passenger train, tank locomotive built for the Prussian state railways in large numbers. These locomotives were superheated variants of the T 11.- History :...

, the T 11 evolved from the T 9.3 in order to replace the older, four-coupled tank engines. Construction of the T 11 was ceased in 1910 in favour of the more economical T 12.

In 1923, 16 engines were fitted with a superheater

Superheater

A superheater is a device used to convert saturated steam or wet steam into dry steam used for power generation or processes. There are three types of superheaters namely: radiant, convection, and separately fired...

, but they retained their existing running numbers.

In 1925, the Deutsche Reichsbahn

Deutsche Reichsbahn

Deutsche Reichsbahn was the name of the following two companies:* Deutsche Reichsbahn, the German Imperial Railways during the Weimar Republic, the Third Reich and the immediate aftermath...

 took over the 358 remaining locomotives as DRG Class 74.0–3, allocating them the numbers 74 001–358.

The locomotives were employed together with the T 12s especially on the Berlin Stadtbahn until its electrification in 1926–1933; as a result they had direction plates (Richtungsschilder) on their smokebox

Smokebox

A smokebox is one of the major basic parts of a Steam locomotive exhaust system. Smoke and hot gases pass from the firebox through tubes where they pass heat to the surrounding water in the boiler. The smoke then enters the smokebox, and is exhausted to the atmosphere through the chimney .To assist...

 and coal tanks. But they were also used in suburban services for other cities such as Frankfurt

Frankfurt

Frankfurt am Main , commonly known simply as Frankfurt, is the largest city in the German state of Hesse and the fifth-largest city in Germany, with a 2010 population of 688,249. The urban area had an estimated population of 2,300,000 in 2010...

, Hamburg

Hamburg

-History:The first historic name for the city was, according to Claudius Ptolemy's reports, Treva.But the city takes its modern name, Hamburg, from the first permanent building on the site, a castle whose construction was ordered by the Emperor Charlemagne in AD 808...

 and Altona

Altona, Hamburg

Altona is the westernmost urban borough of the German city state of Hamburg, on the right bank of the Elbe river. From 1640 to 1864 Altona was under the administration of the Danish monarchy. Altona was an independent city until 1937...

.

At the end of World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 there were still 120 examples of these engines in service, 65 with the Deutsche Bundesbahn

Deutsche Bundesbahn

The Deutsche Bundesbahn or DB was formed as the state railway of the newly established Federal Republic of Germany on September 7, 1949 as a successor of the Deutsche Reichsbahn-Gesellschaft '...

 and 55 with the Deutsche Reichsbahn (GDR) in East Germany. The majority of T 11s were retired by 1960; but two engines (74 231 und 74 240) continued to work the Erfurt industrial railway until 1974.

Two locomotives have been preserved: 74 104 and 74 231. The former was left in Poland

Poland

Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...

 after the Second World War where this class was designated as PKP Class OKi1.
The second was restored in 1998/99 in the Meiningen Steam Locomotive Works

Meiningen Steam Locomotive Works

The Meiningen Steam Locomotive Works is a railway repair shop in Meiningen, Germany. It is owned by Deutsche Bahn and has specialised in the maintenance of museum steam locomotives since 1990, having extensive experience in maintaining steam engines. Today, customers of the factory include...

 for the Minden Museum Railway (MEM) and has been working since 2000. It is the former Hannover 7512.

Design

All four axles of the locomotives – even the carrying axles – were more or less equally loaded with a hefty 16 tonnes. The carrying axle was linked to the first coupled axle via a Krauss-Helmholtz bogie

Krauss-Helmholtz bogie

A Krauss-Helmholtz bogie is a mechanism used on a steam locomotive, where a carrying axle is connected to a coupled axle via a lever such that when the carrying axle swings to the side on going round a curve, it causes the coupled axle to move sideways in the opposite direction...

. The axles were located in a plate frame, inside which a well tank was rivetted.

The first units had piston valves, the later ones slide valves. The riveted boiler

Boiler

A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications.-Materials:...

 barrel comprised two boiler shells and the smokebox

Smokebox

A smokebox is one of the major basic parts of a Steam locomotive exhaust system. Smoke and hot gases pass from the firebox through tubes where they pass heat to the surrounding water in the boiler. The smoke then enters the smokebox, and is exhausted to the atmosphere through the chimney .To assist...

 was also rivetted. At the back of the boiler was the copper firebox. Two vacuum Dampfstrahlpumpen served as feed pumps.

For the brakes, there was, next to the smokebox a single-stage air pump, and in front of the carrying axle were one or two air reservoirs.

T 11 of the Lübeck-Büchen Railway

The Lübeck-Büchen Railway also placed nine T 11s in service between 1905 and 1908.

The four engines taken over by Deutsche Reichsbahn in 1938, with numbers 74 361 to 74 364, were however not the Prussian T 11 - that had already been retired or sold off by then - but the LBE's own special designs based that were more like the Prussian T 9.3 and which had been built in 1911/1912 by Linke-Hofmann

Linke-Hofmann

Linke-Hofmann was a German manufacturing company established in Breslau to produce locomotives and rolling stock. Its origins lay in the wheelwright business of Gottfried Linke, begun in 1834...

in a batch of five. The drive resembled that of the T 11, apart from the smaller coupled wheels with a 1,400 mm diameter, whilst the boiler was smaller too. The last of these engines was not retired until 1951.

Sources

• Jürgen U. Ebel / Hansjürgen Wenzel: Die Baureihe 74, Die Geschichte der preußischen T 11 und T 12, EK-Verlag, Freiburg 1995, ISBN 3-88255-142-9

External links

• Photo of the Polish OKi1 28 (the former DRG 74 104)
• Photo of the Prussian T11 7512 Hannover owned by the Minden Museum Railway (formerly DRG 74 231)
• There is a relevant English-language forum at Railways of Germany