The class D XII tank locomotives were mainly built for the branch lines that ran from Munich into the mountains. At the time they were put into service, they were one of the most powerful tank locomotives and were also purchased by the Pfalzbahn and the Reichseisenbahnen Alsace-Lorraine.

The wheel arrangement 2-4-4T was chosen for the engines in order to be able to accommodate larger quantities of coal and water and to decouple the adhesive weight as far as possible from the filling level of the supplies. The leading axle and the first coupled axle were combined into a Krauss-Helmholtz bogie, while the driving axle had weakened wheel flanges and the rear bogie was mounted so that it could move 27 mm to the sides. As was to be expected, this design resulted in very smooth running.

Palatine Pt 2^II

Die Lokomotive, June 1906

Production for the Bavarian State Railways began in 1897 and included a total of 96 units, two of which were handed over to the Pfalzbahn in 1916. Between 1900 and 1903, 31 engines designated as P 2^II had already been procured there, which were almost identical in construction to the D XII. In Alsace-Lorraine, a total of 37 units were procured between 1903 and 1912, which were initially designated as the T 5 and later as the T 7. If necessary, the latter were also used to transport express trains over short distances between their own network and the Palatinate network.

As successor, superheated Pt 2/5 H from 1906 was considered. However, the trial use showed that this brought hardly any advantages compared to the D XII, which was attributed to the low adhesive weight. So it remained a one-off and nine more examples of the previous design were made in the following year, which were now designated Pt 2/5 N.

Except for the two locomotives that were sold, all remaining 94 D XII were taken over by the Reichsbahn in 1925 and classified as class 73^0-1. They were given the numbers 73 031 to 73 124, since the Palatinate locomotives had already been given the numbers 001 to 028. The nine newest units were given numbers 131 to 139. Most units were retired by 1941, but the last ones only did so in the years after the war.

A problem on the Paris suburban routes of the Nord was that the previously existing tank locomotives with the wheel arrangement 4-4-0T and 0-4-2T had to be turned at the end stations, which led to unacceptable delays, especially in heavy rush hour traffic. Therefore, between 1901 and 1906, the Nord had a total of 75 tank locomotives built for suburban traffic with a symmetrical wheel arrangement, which had been developed by Gaston du Bousquet. Because these locomotives had a high-mounted, small-diameter boiler, they earned the nickname “Revolver”. Due to the design as 4-4-4T, they had a bogie ahead in both directions, which meant that they could be operated in both directions at a maximum speed of 105 km/h.

A special feature in the cab was that the controls were all duplicated to facilitate operation even when reversing. While the adhesive weight of other locomotives with this wheel arrangement was relatively low, the weight of these locomotives was distributed in such a way that more than half was on the two coupled axles. Thus, the two bogies served to guide rather than carry a large mass while providing sufficient adhesive weight. 

Schematic drawing with dimensions

Die Lokomotive, May 1909

The production took place in three batches at La Chapelle in Paris and Hellemmes in Lille. While the water and coal reserves were still 6,500 liters and 3.0 tonnes in the first batch, they were increased to 7,000 liters and 3.5 tonnes in the two following batches. In the SNCF they were listed as 222 TA 1 to 222 TA 75.

Between 1880 and 1890, the Illinois Central purchased a total of 18 Forneys with a 2-4-4T wheel arrangement for suburban service in Chicago. These were made up of two classes that only differed in details and weight. These were six class 213 locomotives built by Rogers in 1880 and twelve class 223 locomotives built directly by the Illinois Central in the Paducah Shops beginning in 1885.

Since the class 223 was heavier than the class 213, the older locomotives were rebuilt in a similar manner. The suburban lines were electrified between 1926 and 1932, which led to the locomotives being transferred to switching service. However, it only took until 1935 for all to be retired. Preserved at the Illinois Railway Museum is 201, originally numbered 213 and participating in the 1893 Columbian Exposition.

One of the few locomotive types that the independent Lithuanian State Railways procured between the world wars was the Tk, built by Škoda. It was a four-coupled tank locomotive that had a leading axle and a bogie at the rear. The bogie ensured that the supplies could be relatively large with 4.5 m³ of coal and 12 m³ of water. With a coupling wheel diameter of 1,600 mm, speeds of up to 90 km/h could be reached. Four pieces were made, which were numbered 11 to 14.

Although tank locomotives with this wheel arrangement were mainly used in suburban traffic in other countries, the Tk was mainly used outside of the large cities and was even used in front of express trains. So they pulled the express train from Berlin to Daugavpils in Latvia for at least 143 km from border to border through the rather small country. From 1939 they were replaced in this role by the Pacific Tender Locomotives Gp. After the Second World War, both surviving pieces had to be handed over to the Soviet Union. One engine each remained in the GDR and in Poland, both of which were no longer in regular service.

The Metropolitan Railway's class H was a tank locomotive for fast passenger services between the suburbs of London and the town of Aylesbury. It was developed as a “double ender” with two driving axles because the 0-6-4T class G had a rigid wheelbase that was too long for the tight curves in the suburbs.

In 1920 and 1921 Kerr, Stuart & Co. delivered a total of eight. They could easily negotiate curves up to 300 feet (91 m) and were designed for trains of 250 tons. When they were taken over by the LNER in 1923 they became Class H2. In 1941 they were relocated to Nottingham, but between 1942 and 1947 they were all scrapped.

The North Eastern Railway's class D was developed by Vincent Raven for rural passenger trains. In order to achieve equally good running characteristics in both directions of travel, he chose a tank locomotive with a 4-4-4T wheel arrangement. Three cylinders ensured smoother acceleration. Although there were only two axles available for traction, the coefficient of adhesion of more than four indicated that there was enough traction for starting without slipping.

In 1913 the first 20 were built in Darlington. Another 25 followed after the war in the years 1920 to 1922. The LNER took over the locomotives as class H1. Between 1931 and 1936, all were rebuilt to a 4-6-2T wheel arrangement. These were designated class A8 and were retired between 1957 and 1960.

Since the expected number of passengers in express traffic in the 1930s was low and the existing tracks did not allow high axle loads anyway, the Hungarian State Railways developed a light streamlined tank locomotive. With one bogie in front and one behind, the four locomotives were allowed to travel 120 km/h in both directions. A speed of 152 km/h was reached during a test drive and in 1961, after the installation of a double blast pipe, even 160 km/h were reached. As with German streamlined locomotives, the panels were later cut out in the area of the wheels.