Patent ID: 7306192

Claim:
A height-adjustable chair column comprising a vertical post having a longitudinal axis, a first upper end area, and a second lower end area; a bottom plate mounted in the second lower end area of the vertical post; a guide cylinder bushing permanently inserted into the first upper end area of the vertical post; a guide tube inserted in the guide cylinder bushing so as to be guided with freedom of axial movement and secured against rotation in the guide cylinder bushing, the guide tube having an upper end region projecting out from the guide cylinder bushing; a lockable gas spring assembly including: a pressure cylinder having a first closed end portion projecting out from the first upper end area of the vertical post, and a second end portion arranged within the vertical post, the pressure cylinder being installed coaxially in the guide tube so as to be secured against axial displacement relative to the guide tube, while being free to rotate about the longitudinal axis relative to said guide tube, and a piston axially movably arranged in the pressure cylinder, the piston being connected to a piston rod sealingly extending through the second end of the pressure cylinder, wherein the piston rod comprises a lower end which is fastened to the bottom plate and supported there with freedom of rotation about the longitudinal axis; and a height-adjustable foot rest which is attached to the upper end region of the guide tube.