Abstract: A device for the continuous change of the flow rate of a viscous medium e.g. hydraulic oils or lubricating greases with e.g. a conical throttle insert (1) with a smooth surface and axially movable in a conical bore (3) of a housing (4) in such a manner that different gap widths and/or lengths between throttle insert (1) and housing (4) connect a housing inlet (5) with a housing outlet (6) for the medium. Alternatively, the device may include circular cylindrical throttle insert (1) having a circumferential spiral groove (2) and being axially movable in a circular cylindrical bore (3) of a housing (4) in such a manner that different lengths of the circumferential groove (2) connect a housing inlet (5) with a housing outlet (6) for the medium being metered.