The invention relates to a hydraulic tensioning system (1) designed for tensioning a belt (11) of traction machine drives (12) in internal combustion engines. The traction machine drive (12) comprises a belt (11) circulating through an oil bath or an oil mist. The tensioning system (1) encompasses a housing (2) in which a piston (9) acted upon by a hydraulic fluid is guided in a linearly movable fashion, said piston encompassing a tensioning rail (7) cooperating with the belt (11) in the operating state. The tensioning rail (7) is pivotally mounted on the housing (2) via a joint (6).
