Klemens Stefan Sielecki (December 8, 1903 in Stanisławów, Austria-Hungary – July 14, 1980 in Kamień Pomorski, Poland) was a Polish engineer and technical director of the first Polish Locomotive Factory Fablok in Chrzanów in the post-war years until 1964. Biography His father Sofroniusz Skrebeciowicz de Sielecki (1862–1908) was civil servant at the Imperial Royal Austrian State Railways, stationed in various places throughout Galicia. His mother Leontyna née Lintner (1877–1913). He had one younger sister, Czesława (1907–1993). Both became orphans at an early age and were raised by their maternal aunt Jozéfina and her husband Adolf Skrzyszewski, who was also employed at the state railway. The Skrebeciowicz de Sielecki family with the Sas coat of arms was nobility (in Polish called szlachta), originally from Sielec, Drohobych Raion. Klemens Sielecki went to primary school in Chernivtsi and the Imperial and Royal Gymnasium V in Kraków and received his matriculation in Stanisławów in 1921. He enrolled in the Lwów Polytechnic on November 24, 1921, where he studied engineering and railroading and graduated on December 14, 1929 with a master's degree. During his studies in 1925, after three months of interning he received his steam engine-driving license. In the year 1925-26 he did his internships in the workshops and offices of the state railway of Lwów and Stanisławów and familiarised himself with the production of steam locomotives of Fablok in Chrzanów and the Steam Locomotive Factory in Warsaw (Fabryka Parowozow Warszawa). After earning his absolutorium in 1927, he worked in the locomotive depot in Lwów in the gauging department and later as a designer in the mechanical factory in Lwów "L. Zieleniewski-Fitzner-Gamper SA". From October 1, 1928 until April 30, 1930 he worked as a young assistant at the chair of engineering (I Katedry Budowy Maszyn) under professor Wilhelm Mozer and at the same time as assistant at the university don for organisation and management of industries at the Lwów Polytechnic. On May 1, 1930 he moved to Chrzanów, where he started work in the design office of Fablok in charge of developing new types of locomotives for the then ministry of communication (which later became the ministry of transport) and the Bulgarian State Railways. In 1935 he was highly involved in the development of the construction of the diesel hydraulic railway car called "Luxtorpeda", which was a technical innovation in its time. Also in 1935 he was nominated as deputy head of the