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 433.0 series.
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 coupled axle, which served as the driving axle, was equipped with weakened wheel flanges and the first coupled axle could be shifted by 21 mm to each side. A water purifier was installed to take account of the often polluted boiler feed water on branch lines. This was cylindrical and, together with the steam dome and the sandbox, lay under a panel on the boiler barrel.
A total of 231 units were manufactured until 1946. With an indicated output of more than 750 hp, the engines were also called “Velký Býcek” or “Big Bull”. Some engines in the Sudetenland came under the control of the Deutsche Reichsbahn from 1938 and were listed as the class 9315 at this time. During the Second World War they all came back to the CSD area. They were in service until the late 1970s and it was not until 1980 that the last two examples were retired. Five examples survive today, three of which are in working order.