Inhalation device for medically active liquids for generation of an aerosol, comprising - a housing, inside this housing a reservoir for storing a liquid, a pumping unit, said unit comprising a riser pipe, a hollow cylindrical part having an interior space configured to receive an upstream end portion of said riser pipe, said cylindrical part being linearly moveable on the riser pipe, wherein the cylindrical part and the riser pipe form a pumping chamber having, by means of linear relative motion of the cylindrical part with respect to the riser pipe, a variable volume for generation of a pressure inside said pumping chamber, wherein - the pumping chamber is fluidically connected with the reservoir and with a nozzle which is connected liquid-tight to a downstream end portion of the riser pipe, and wherein - said linear relative motion can be effected by a relative rotation around a rotational axis of a rotatable part which is part of, or connected to, a first part of the housing with respect to a counterpart which is part of, or connected to, a second part of said housing, such that said relative rotation is converted into said linear relative motion by means of a gear mechanism, said gear mechanism comprising at least one cam surface comprising, in axial direction, a first section of increasing height as well as a second section of decreasing height, the cam surface being capable of sliding along an adjacent counterface, wherein the cam surface is, upon rotation, adapted to slide along said counterface, resulting in said conversion, and wherein - a means for the storage of potential energy is provided which is chargeable by means of said relative rotation along the first section, and wherein said energy is releasable to said pumping device when released, and wherein said cam surface comprises, between the first section of increasing height and the second section of decreasing height, a third section of constant height, such that, while said third section of said cam surface slides along the counterface, no linear relative motion of the cylindrical part with respect to the riser pipe occurs, and wherein - a dosing cycle which covers the rotation angle of the first, the second, and the third section (9A, 9B, 9C), corresponds to a rotation of 180 degrees. - a housing, inside this housing a reservoir for storing a liquid, a pumping unit, said unit comprising a riser pipe, a hollow cylindrical part having an interior space configured to receive an upstream end portion of said riser pipe, said cylindrical part being linearly moveable on the riser pipe, wherein the cylindrical part and the riser pipe form a pumping chamber having, by means of linear relative motion of the cylindrical part with respect to the riser pipe, a variable volume for generation of a pressure inside said pumping chamber, wherein - the pumping chamber is fluidically connected with the reservoir and with a nozzle which is connected liquid-tight to a downstream end portion of the riser pipe, and wherein - said linear relative motion can be effected by a relative rotation around a rotational axis of a rotatable part which is part of, or connected to, a first part of the housing with respect to a counterpart which is part of, or connected to, a second part of said housing, such that said relative rotation is converted into said linear relative motion by means of a gear mechanism, said gear mechanism comprising at least one cam surface comprising, in axial direction, a first section of increasing height as well as a second section of decreasing height, the cam surface being capable of sliding along an adjacent counterface, wherein the cam surface is, upon rotation, adapted to slide along said counterface, resulting in said conversion, and wherein - a means for the storage of potential energy is provided which is chargeable by means of said relative rotation along the first section, and wherein said energy is releasable to said pumping device when released, and wherein said cam surface comprises, between the first section of increasing height and the second section of decreasing height, a third section of constant height, such that, while said third section of said cam surface slides along the counterface, no linear relative motion of the cylindrical part with respect to the riser pipe occurs, and wherein - a dosing cycle which covers the rotation angle of the first, the second, and the third section (9A, 9B, 9C), corresponds to a rotation of 180 degrees.