| 摘要 |
A device (1) for adjusting the tilt of a chair backrest having a backrest frame (3) rotatable with respect to the base frame (2) of the chair, comprises elastic means (5) for returning the backrest and/or countering the rotation thereof, in addition to means for controlling the preload of the elastic means (5). The means (6) for controlling the preload comprise at least one first connecting rod (7) and at least one first crank (8). The first connecting rod (7) is hinged to the first crank (8) and constrained to the elastic means (5) such as to move the point of application (13) of the returning and/or countering force with respect to the backrest. Adjusting means (9) to adjust the position of the first crank (8) determine at least two distinct stable positions of the first crank (8) corresponding to two distinct positions of the mentioned point of application (13) of the returning and/or countering force with respect to the base frame (2). |
