Czechoslovak State Railways class 423.0

In order to get a more powerful successor for the large number of existing branch line tank locomotives, the class 423.0 was developed by the First Bohemian-Moravian Machine Works (PCM) and also manufactured by other companies. In order to achieve the greatest possible power, the choice fell on the 2-8-2T wheel arrangement. Later they also formed the basis for the class 433.0.

A lot of attention was paid to the running gear in order to achieve sufficient running characteristics on branch lines despite the six axles. While the two carrying axles were designed as Adams axles, the third driving axle, that served as main driver, was equipped with thinner flanges and the first driving axle had lateral play of 21 mm to each side. A water purifier was installed to take account of the often polluted feed water on branch lines. This was cylindrical and, together with the steam dome and the sandbox, was situated under a panel on the boiler barrel. 

A total of 231 were manufactured until 1946. With an indicated output of more than 750 hp, the locomotives were also called “Velký Býcek” or “Big Bull”. Some locomotives in the Sudetenland came under the control of the Deutsche Reichsbahn from 1938 and were listed as class 93¹⁵ at this time. During the Second World War they all came back to the ČSD network. They were in service until the late 1970s and it was not until 1980 that the last two were retired. Five survive today, two of which are in working order.