The invention relates to a supply device for the supply of pressure fluid into at least one vehicle brake, into a pressure fluid reservoir or into a pressure fluid accumulator, with a pressure fluid inlet and a pressure fluid outlet as well as with the following features: a piston is movably arranged in an accommodating member and has at least two hydraulically active diameters for the supply in the direction of the pressure fluid outlet, at least one non-return valve is used for the ventilation of a working chamber into which the piston is immersed. It is the essence of the invention that the piston has a multi-part design and comprises at least two synchronously movable partial pistons, with the first partial piston exhibiting the first hydraulically active diameter, and the second partial piston exhibiting the second hydraulically active diameter.