When the class 380 with a 2-10-0 wheel arrangement could no longer cope with the increased weight of the express trains on the Tauern Railway, Gölsdorf had to develop an even more powerful mountain express locomotive. Since the maximum axle load was still limited to 13.8 tonnes, a total of six axles was no longer sufficient. Based on his previous experience with laterally adjustable coupled axles, he dared to develop a twelve-coupled locomotive for the winding mountain route for the first time.

In order to be able to negotiate curves with a radius of 150 meters, the leading axle could be radially adjusted by 50 mm and three of the driving axles could be shifted laterally. The freedom of movement of the second and fifth coupled axle was 26 mm and that of the sixth 40 mm. The third, which was the driving axle, had no wheel flanges. To prevent the coupling rods from jamming in curves, these were connected to the crank pins on the last two axles with cardan joints.

The boiler tapers towards the front and was the largest that had been installed on an Austrian locomotive to date. With the oil firing, this generated an output of 2,020 hp. Express trains weighing 360 tonnes could be pulled at 40 km/h on the Tauern Railway's incline of 2.8 percent. In order to comply with the axle loads, the lightweight construction of the locomotive was taken to the extreme in many places, which later led to problems with durability.

Sectional drawing with dimensions

Die Lokomotive, November 1911

Although the chassis showed good running characteristics on test runs at up to 92 km/h, it was only approved for 60 km/h. However, it remained with a single locomotive, which was taken over by the BBÖ after the First World War and was not built again due to the plans for electrification. It was retired in 1928 after a rupture in one of the inner cylinders. In Württemberg, the otherwise good experience with the locomotive was used as an opportunity to develop the K with the same wheel arrangement.

Since articulated freight locomotives in the 1920s did not yet reach the same speeds as ten-coupled locomotives, Union Pacific had the class 9000 developed with six coupled axles in one frame. The unique wheel arrangement with a four-wheel leading bogie, six sets of drivers and a two-wheel trailing truck was called “Union Pacific” by the UP. The 1926 prototype was officially given the class designation UP-1, while further batches were designated UP-2 to UP-5.

Only the fourth driving axle had no wheel flanges, but the first and sixth could be moved laterally by two inches. In order to be able to use the steam from the large boiler, three cylinders were installed. The middle one was offset upwards at an angle and was controlled by the outer cylinders via a Gresley valve gear.

In addition to the UP, two subsidiaries also received additional locomotives of this type, so that the total number ultimately reached 88. These were eight on the Oregon–Washington Railroad and Navigation and 15 on the Oregon Short Line Railroad. Although they were only intended for speeds of 35 mph (56 km/h), they often reached 45 to 50 mph with freight trains and could easily reach 60 mph (97 km/h) while running steadily.

Their area of operations focused on Nebraska, where they increased the speed of freight trains in the flat land. However, it became apparent that the Gresley valve gear's friction bearings were subject to high levels of wear. Only in eight of the oldest locomotives was this replaced with a Walschaerts valve gear and in the machines built from 1928 the Gresley valve gear was given roller bearings.

During the Second World War they had to work hard and were no longer adequately maintained. This meant that some were set aside during the war. The entire class was withdrawn from service between 1953 and 1956. The only surviving locomotive is the prototype number 9000. It is not operational and belongs to the Railway & Locomotive Historical Society in Pomona, California.

In order to be able to haul the ever heavier freight trains on the Württemberg routes without double-heading, the class K with a 2-12-0 wheel arrangement of was procured from Maschinenfabrik Esslingen from 1917 onwards. They were the only twelve-coupled locomotives in Germany. The reason for the large number of wheel sets was that the axle load was limited to 16 tonnes and it would therefore not have been possible to build a sufficiently powerful machine with an 0-10-0 or 2-10-0 wheel arrangement.

In order to enable good running in curves, the first and sixth coupled axles were designed to be laterally displaceable according to the Gölsdorf system and the wheel flanges of the third and fourth wheel sets were weakened by 15 mm. In addition, the leading axle could be adjusted radially and shifted laterally. The locomotives were powered by a four-cylinder compound engine with power transmission to two axles according to de Glehn. The inner high-pressure cylinders acted on the third coupled axle and the outer low-pressure cylinders on the fourth. The second coupled axle also had to be cranked so that the connecting rods of the high-pressure cylinders had enough space. In addition to the Württemberg tenders, Prussian tenders, which had a larger capacity, were also used later.

The first production lot consisted of three locomotives, construction of which began in 1917 and could be delivered in January 1918. A further twelve locomotives were delivered in 1919. Since there was still a need after the founding of the Reichsbahn, another 29 units were built in 1923 and 1924, bringing the total to 44. The locomotives were mainly used on the Geislinger Steige and the Black Forest Railway, where they proved themselves extremely well. In the lowlands, however, they used more steam than lighter machines, which also had sufficient power there. After the Geislinger Steige was electrified in 1933, the locomotives, now known as class 59, were distributed to other mountain routes in Württemberg. After 1938, when Austria was annexed by the German Reich, a large part of the locomotives came there and were used, for example, on the Semmering Railway.

This was the reason why 30 class K locomotives remained in Austria after the end of the war. Some had to be handed over to either the Soviet Union or Hungary as reparations, others were returned to the Deutsche Bundesbahn. The remaining four were designated class 659 and retired between 1951 and 1957.

The Bundesbahn also didn't find much use for the class 59, since the standard and war locomotives constituted to thousands of equally powerful freight locomotives available. In particular, the class 44, with only five coupled axles but a greater axle load, was able to generate even more power. Thus, most of the machines that returned to West Germany from Austria or Hungary were immediately scrapped and the rest all disappeared by 1953 at the latest.