Abstract: An oscillation system (1) for chairs includes a backrest support (3) oscillating about a rotation axis (4), a first support element (6) of the seat coupled to the frame (2) to assume, in the at rest position of the backrest support (3), a plurality of relative vertical positions with respect to the frame (2) depending on, and by effect of, a weight force applied to the first support element (6). A first elastic element (21) opposes an elastic reaction to the backrest support oscillation with respect to an at rest position of the backrest support (3). A lever (31) connects to the first support element (6) to be rotated by the first support element (6) during variation of the relative position, and connects to the first anchoring end (22) to displace the first anchoring end (22). A fulcrum axis (60) does not coincide with the rotation axis (4).

Abstract: A tilting mechanism (1) for chairs includes a support frame (2), a structure (4) rotationally coupled to the support frame. An elastic system (80) is interposed between the support frame and the structure to counteract a reaction to the tilting of the structure from an at-rest position to a tilted position. An adjustment system (20) is capable of varying the reaction to the tilting. The elastic system (80) includes at least one elastic element (12) and a first and a second stop element (81, 82) fastened at respective longitudinal end portions of the elastic element, respectively. In the at-rest position, the first and second stop elements are in contact with each other, and the elastic element (12) is in a deformed configuration and generates a residual elastic force that is at least partially released on the first and second stop elements.

Abstract: An oscillation mechanism for chairs includes a support frame, a structure coupled to the support frame to rotate about a first axis, an elastic element interposed between the support frame and the structure and configured to oppose a reaction force to an oscillation of the structure. The reaction force generates a reaction moment acting on the structure with respect to the first axis. An oscillation adjustment system is able to vary the reaction moment with the oscillation being unchanged. The adjustment system includes a pin movably coupled to the structure and a movement system of the pin for varying the distance between the pin and the first axis. The elastic element is directly fastened to the pin so that the reaction force is transmitted to the structure with the application point corresponding to the pin and with direction and orientation unchanged.

Abstract: An oscillation mechanism for chairs includes a support frame, a structure coupled to the support frame to rotate about a first axis, an elastic element interposed between the support frame and the structure and configured to oppose a reaction force to an oscillation of the structure. The reaction force generates a reaction moment acting on the structure with respect to the first axis. An oscillation adjustment system is able to vary the reaction moment with the oscillation being unchanged. The adjustment system includes a pin movably coupled to the structure and a movement system of the pin for varying the distance between the pin and the first axis. The elastic element is directly fastened to the pin so that the reaction force is transmitted to the structure with the application point corresponding to the pin and with direction and orientation unchanged.

Abstract: An adjustment device for chairs, comprising a main body (2), which can be engaged onto a supporting shank (3) of a chair; a prop element (6) mounted above the main body (2), which can be associated to a seat for a user; a backrest (10) mounted onto the main body (2), which can be associated to a back (11) for a user; and articulation means (14) for movably engaging the backrest (10) and the prop element (6) to the main body (2), the articulation means (14) comprise at least one lever (17) pivoting around the main body (2) in a first mounting site and having at least two lever portions (17a, 17b) hinged to the prop element (6) in a second mounting site and to the backrest (10) in a third mounting site, respectively, so as to obtain a given movement relation between the backrest (10) and the prop element (6).

Abstract: An adjustment device for chairs, comprising a main body (2), which can be engaged onto a supporting shank (3) of a chair; a prop element (6) mounted above the main body (2), which can be associated to a seat for a user; a backrest (10) mounted onto the main body (2), which can be associated to a back (11) for a user; and articulation means (14) for movably engaging the backrest (10) and the prop element (6) to the main body (2), the articulation means (14) comprise at least one lever (17) pivoting around the main body (2) in a first mounting site and having at least two lever portions (17a, 17b) hinged to the prop element (6) in a second mounting site and to the backrest (10) in a third mounting site, respectively, so as to obtain a given movement relation between the backrest (10) and the prop element (6).