Class 423D 4-8-0 (1954)

Class 423D 2-Cylinder General Purpose Locomotive
Designed by Mikhail Rodnivacek
Built in 1954 by Friedrich Krupp, Essen, Germany

It was, indirectly, thanks to Frihdrik Tešlov that these fine locomotives and their 4-8-4T cousins were built by Krupp. The contract for their construction was awarded just after Tešlov's 2-10-2s entered traffic and impressed everyone. The design, of course, came from the drawing board of Mikhail Rodnivacek, who was at this time in the process of renewing the RSR's locomotive stock. There was a clear need for a modern, medium-sized mixed traffic engine for the mountain routes in the south. With their eight-coupled, 1560mm wheels, the 423Ds struck the right balance between speed and pulling power. The standard 2c boiler was pitched high to accommodate the wide firebox above the driving wheels. A total of seventy 423Ds were delivered by Krupp during 1954 and 1955. The changeover to poppet valves on the RSR was proceeding apace when these locomotives were delivered and came just too late for the order to Krupp to be amended. Starting in 1956, all engines were converted at the first opportunity (usually in connection with the first general overhaul), becoming class 423DD.

Class 433DD 4-8-0 with poppet valves

In this form the engines remained the mainstay of medium services in the south until the mid-1980s, when the 58 survivors were rebuilt to class 434E.