Pd4 was a Polish designation for the Polish State Railways express steam locomotive of the PrussianS5² series, produced between 1905 and 1911. In German railways, it was designated as series (Br) 136-8. The locomotive had a two-cylinder compound steam engine using saturated steam. In Poland, during the interwar period, 29 locomotives of this series were in operation, and after the war, 14 were operational until 1955.