Patent ID: 6840484

Claim:
A gas cylinder for use in a chair, comprising: a pipe holder having a gas opening/closing pin for intermittently controlling gas flow; a spindle having the pipe holder on its upper inside, said spindle having a predetermined sealing means on its lower side, said spindle further having a flange washer formed on a lower end of the sealing means, and said flange washer consisting of a first region and a second region, wherein the first region has an inner diameter larger than that of the second region, and wherein the first region has a height higher than that of the second region, said spindle including an upper end adapted for affixing to a seat of a chair; a piston inserted into an inside of an opened cylinder of the spindle; a piston rod having one end fixed in the piston; and a base tube of a cylindrical shape having a mounting member on which a lower end of the spindle is mounted with the mounting member inserted to an inside of the first region of the flange washer, and for fixing the other end of the piston rod in its lower side, and whose inner periphery guides an outer periphery of the spindle, the base tube having a lower side adapted for affixing in a base of a chair.