Patent ID: 8393447

Claim:
A vibration damper comprising: a damping medium filled cylinder in which a piston rod carrying a working piston is guided with freedom of axial movement, the working piston dividing the cylinder into a working space on the piston rod side and a working space away from the piston rod; and a housing having an inside wall, a cover, and a bottom piece arranged opposite the cover, the housing having first and second working chambers separated by a separating piston, that is moveably arranged in the housing, the first working chamber being connected to one of the working spaces to provide amplitude selective damping as said working piston moves in said cylinder, wherein the separating piston is spaced from the inside wall to form an annular gap in which a pressure gradient develops when the piston rod moves, the separating piston being radially expandable to close the gap when at least one of sufficient pressure develops in one of the working chambers and when the separating piston contacts one of the cover and the bottom piece, wherein the working piston comprises: first and second pass through cross sections arranged between the first and the second working spaces; and first and second valve disks arranged to at least partially cover respective axial ends of the first and the second pass through cross sections, wherein the first and second valve disks are open at least when the gap is closed, whereby the first and the second working spaces are connected to at least one of the annular gap and the first and the second pass through cross sections.