Patent ID: 6935478

Claim:
A fluid friction clutch, comprising: a rotatably mounted shaft; a drive body which is mounted in a rotationally fixed manner on the shaft; an output body, mounted rotatably on the shaft and at least partially surrounding the drive body; a clutch region arranged between the drive body and output body, which accommodates a viscous fluid and can be used to couple drive body and output body in order to transmit a torque; a reservoir for at least largely holding the fluid positioned radially inside an outer periphery of the drive body; at least one first flow path for return of the fluid from the clutch reunion into the reservoir and at least one second flow path for for supplying the fluid from they reservoir into the clutch region; at least one flow resistance element located at the outer periphery of the drive body and arranged between the first flow path and the second flow path, and a controllable device for selectively closing and opening at least one of the first and second flow paths.