Abstract: A seat assembly including a seat base, a back support, a support for the back support and/or for the seat base and at least one elastomer torsion-spring element. The back support and/or the seat base are/is pivotably hinged to the support in such a manner that a pivoting movement of the back support and/or of the seat base on a rotation axis can be carried out. During the respective pivoting movement of the back support and/or of the seat base with the elastomer torsion-spring element a restoring torque is generated that acts on the back support and/or on the seat base. The elastomer torsion-spring element includes an internal casing, an external casing encompassing the internal casing, and an elastomer body arranged in a space between the internal casing and the external casing. The elastomer body is rigidly connected to contact surfaces of the internal and external casings. The internal casing and/or the external casing are/is rotatably arranged on a rotation axis.

Abstract: A support structure for a back part and/or a seat of a seat assembly includes a base support, a support part, and a power system. The support part is arranged on the base support to support and/or hold the respective back part and/or seat, and is attached to the base support to allow movement of the support part relative to the base support. The power system, which includes first and second spring elements and a coupling device, generates a reset force in response to (and directed opposite to) the respective movement of the support part. When the coupling device is in a first state, the second spring element generates a second reset force directed opposite to the movement of the support part. When the coupling device is in the second state, the second spring element does not generate the second reset force.

Abstract: A seat assembly including a seat base, a back support, a support for the back support and/or for the seat base and at least one elastomer torsion-spring element. The back support and/or the seat base are/is pivotably hinged to the support in such a manner that a pivoting movement of the back support and/or of the seat base on a rotation axis can be carried out. During the respective pivoting movement of the back support and/or of the seat base with the elastomer torsion-spring element a restoring torque is generated that acts on the back support and/or on the seat base. The elastomer torsion-spring element includes an internal casing, an external casing encompassing the internal casing, and an elastomer body arranged in a space between the internal casing and the external casing. The elastomer body is rigidly connected to contact surfaces of the internal and external casings. The internal casing and/or the external casing are/is rotatably arranged on a rotation axis.

Abstract: A synchronous office chair comprising a support (1) firmly connected with a supporting column, a seat base (2) articulated on a tilting axis (4) support with a flange (5) and a backrest (3) with a back bracket (6). The back bracket (6) features a first, second and third cam tracks (7, 8, and 9) and engages in an interstice between support (1) and seat base (2). Said seat base (2) with flange (5) and backrest (3) with back bracket (6) are formed to execute a synchronous movement. A first roller bearing (10) is mounted on flange (5) of seat base (2) that engages in the first cam track (7) of back bracket (6) and in which the synchronous movement is guided in first cam track (7). A second roller bearing 11 is mounted on seat base (2) that engages in second cam track (8) of back bracket (6) and in which synchronous movement is guided in second cam track (8).