Fluid friction clutch

A fluid friction clutch (1) comprising:

• a housing (2, 3);
• a clutch plate (4) rotatably disposed in the housing (2,3), the clutch plate (4) and the housing (2, 3) forming a working chamber (9);
• a reservoir (10) disposed in the housing (2, 3);
• a supply conduit (11A, 11B) coupling the reservoir to an inlet side of the working chamber (9);
• a supply pump element (14) that is rotatably coupled to the clutch plate (4), the supply pump element (14) being spaced radially apart from a surface on the housing (2, 3) such that a shear gap (12) is disposed between the supply pump element (14) and the surface on the housing (2, 3), the supply pump element (14) having a pump inlet and a pump outlet that are spaced circumferentially apart from one another about a rotational axis of the clutch plate (4), the pump outlet being coupled in fluid communication with the supply conduit (11A, 11B);
• a valve (17) arranged in the clutch plate (4), the valve (17) having a valve element (13) that is movable between a first position, in which the valve element (13) extends from the clutch plate (4) to at least partly block fluid flow to the pump outlet, and a second position in which the valve element (13) is retracted into the clutch plate (4) relative to the first position of the valve element (13).