Steam locomotive class Hh of the Royal Württembergian State Railroad, Type 0-10-0
The main load of freight traffic of the Königlich Württembergische Staats-Eisenbahnen (K.W.St.E.) was carried by the three-coupled class F and Fc freight locomotives. There were only a few five-coupled class G Klose locomotives which were used particularly for steep inclinations.
The increase in freight traffic meant that freight trains had to be coupled more frequently to two locomotives. This however was very uneconomical and the K.W.St.E. wanted to produce a freight locomotive which could take twice as much traction power as a class Fc locomotive. The result was the class H five-coupled freight locomotive. In 1905 and 1909 a total of 8 of these saturated steam interlocking locomotives were put into service. These locomotives were 75% more powerful than the Fc class ones. In 1909, class H was updated to a superheated steam locomotive of class Hh. The boiler was redesigned and a twin engine was used instead of the compound engine. The new design proved to be worthwhile, in comparison to the saturated steam locomotives the performance levels could now be increased by 7%, whilst at the same time reducing the fuel and water consumption.
From 1909 to 1920, 28 saturated steam locomotives were put into service, all of which were manufactured at the machine factory in Esslingen. These locomotives were desperately required by the traction haulage service in order to pull the extremely heavy freight trains. The first machines arrived in the machine disctrict in Stuttgart, then later in Ulm. In both regions they were primarily used on the main Bretten–Stuttgart–Ulm route.
