The G 8 was the first superheated goods steam locomotive in Prussia. A total of 1,054 were built between 1902 and 1913, its development G 81 even more than 5,000 times. The design came from Vulcan, but due to the number of engines, production took place at various manufacturers.
Schematic drawing of a G 8 with Lentz valve gear
Die Lokomotive, August 1911
In order to be able to use them on poorly developed branch lines, an axle load of only around 14 tonnes was aimed for. The fact that the locomotive had no carrying axle proved to be an advantage here, since its entire weight was available as adhesion mass. Although only the second axle could be moved sideways, the engine had a good ability to negotiate curves. For this reason, the top speed was soon increased from 50 to 60 km/h.
G 8 “Mainz 4981” of the railway museum Darmstadt-Kranichstein in August 2013 in Frankfurt am Main
Friedrich-Karl Mohr 
A disadvantage of the low axle load was that many components had to be made lighter than was actually necessary, which reduced the power. In addition, there were still some problems with the superheater technology, which is why the G 9 was built again as a saturated steam locomotive from 1908. The early examples of the G 8 still had a smokebox superheater, while the others had a smoke tube superheater.
To increase the power of the G 8, later engine received a larger cylinder diameter, increasing from the original 575 first to 590 and then to 600 mm. In tests, the variant with 590 mm was able to move a 1,637-tonne coal train at 38 km/h on a gradient of 0.33 percent, although the boiler pressure was only kept at ten instead of twelve bar in the test. Also, later there was a firebox with a larger grate and more heating surface and also a superheater with more surface. Furthermore, attempts were made with uniflow cylinders and a Lentz control, which, however, did not bring the hoped-for success.
In 1925, the Reichsbahn took over 656 units with the numbers 55 1601 to 55 2256. In 1935, the stock was supplemented by twelve units from the Saarbahn and during the Second World War further locomotives from Poland were returned to the Reichsbahn. After the war, the Bundesbahn received the majority of the remaining engines with 205 units. These were retired by 1955. The Reichsbahn kept the last of their 50 locomotives until 1969. Today there is still one engine that was used to build the Baghdad railway and later returned from Turkey.