Abstract: The invention concerns a transmission mounted in a housing between a turbine and a generator on top of a tower of a wind turbine, comprising a gearbox and in the gearbox a main gear mounted on a main gear shaft and a pinion that engages a set of gear teeth of the main gear. The pinion is mounted on a pinion shaft and the pinion shaft is coupled to a hydraulic pump mounted on the gearbox, a hydraulic motor drives the generator. In accordance with the invention the main gear shaft and the rotor shaft together form a common shaft and a main gear shaft bearing is mounted between the common shaft and the gearbox and at least two tension bars prevent the rotation of the gearbox and leave the gearbox free to move in linear directions.