Chair with its backrest adjustable in its angle

Claim 1

A chair having a seat, a tiltable backrest secured to the seat, a bottom support and an air pressure cylinder connected between the bottom support and the seat for adjusting the height of the seat, the cylinder having a press button at an upper end thereof for controlling operation of the cylinder, the chair further including a U-shaped plate supported at an upper end of the cylinder and having upwardly extending side walls, the press button projecting from said plate between the side walls, an intermediate plate connected to said U-shaped plate, a base plate with upstanding side walls connected to the intermediate plate, the upstanding side walls of the base plate being connected to an undersurface of the seat, a U-shaped bracket on the base plate between the side walls and having upstanding front and back walls with aligned holes therein, a steering rod extending through said holes for front and back movements, a limit plate connected to the backrest and a tube element on the limit plate for receiving one end of the steering rod when the backrest is in an upright position and the rod is moved back in said holes to prevent the backrest from tilting and for releasing said one end of the rod when the rod is moved forward in said holes allowing the backrest to tilt backwards.