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.

A chair assembly includes a back support arrangement including a back support arrangement, a seat support arrangement and a four-bar arrangement that includes a rearward end and a forward end that is adjustable between a raised and lowered positions, and an arm rest assembly adapted to support the arm of a seated user thereon and supported on the forward end of the four-bar arrangement, wherein the rearward end of the four-bar arrangement is pivotably supported from an arm support structure for pivotable movement about a substantially vertical pivot axis such that the forward end of the four-bar arrangement is moveable between a first position and second position located laterally outward from the first position, and wherein the substantially vertical pivot axis is located forwardly of a rearmost edge of an upwardly-facing surface of the seat support arrangement.

A chair control assembly includes a base structure having first and second pivot points spaced from one another, a seat support structure coupled to the first pivot point, a back support structure coupled to the second pivot point and adapted to move between first and second positions, wherein the base structure does not move as the back support structure moves between the first and second positions, and a control link pivotably coupled to the seat support structure for rotation about a third pivot point and pivotably coupled to the back support structure for rotation about a fourth pivot point, wherein the third pivot point is rearward of the fourth pivot point when the back support structure is in the upright position, and the third pivot point moves forward relative to the fourth pivot point as the back support structure moves from the upright to reclined positions.

The invention relates to a chair (1) which comprises a support (6), a seat element (5), a back element (4), a leg element (3), a spring mechanism and a weight-controlled working adjusting element for the spring mechanism.

A seat tilting mechanism comprising a main body, a support member rotationally mounted to said main body, and a first extension coil spring mounted between said main body and said support member to provide resistance to rotation of said support member, in which said seat tilting mechanism further comprises a second extension coil spring and an engagement mechanism which engages said second extension coil spring for resistance to rotation of said support member when said first extension coil spring reaches a pre-determined point of extension.

A seating unit component assembly comprises a support component that includes a first surface adapted to abut a seated user, a second surface opposite the first surface, a first end surface, a second end surface opposite the first end surface, and a pair of side surfaces extending between the first and second end surfaces, and a cover having a plurality of sides that cooperate to form an interior space that receives the support component therein, wherein the cover includes a first portion comprising a non-fabric substantially flexible thermoplastic material covering at least a portion of at least one of the side surfaces of the support component, a second portion comprising a fabric covering at least a portion of the first surface and at least a portion of the first end surface of the support component, and a third portion comprising a substantially rigid overlay covering at least a portion of the second end surface and at least a portion of the second surface.

A chair, comprising, a backrest, a seat coupled with the backrest, a column coupled with the seat, a linkage statically attached to the backrest and rotatably attached below the seat, a leaf spring statically attached at one end and in direct contact with the linkage to provide a resistance to tilting of the backrest relative to the column. A first structure fixed to the column, where a portion of the first structure has an arc shape that includes one or more teeth, and a second structure in contact with the first structure, wherein a portion of the second structure includes one or more teeth. The chair is configured such that, when a weight is applied to the seat, the one or more teeth of the second structure, a pivot point at which the backrest is configured to tilt relative to the column, and the linkage are configured to move together.

A mechanism for an office chair has a base support which is placeable on a chair column. A seat support is arranged on the base support and is movable relative to the base support. A backrest support is coupled with the seat support. Pivoting the backrest causes the seat support to move relative to the base support. An alternative solution for adjusting the tilting resistance of the seat support of an office chair is provided where the tilting resistance of the seat support is influenced by the pivoting resistance of the backrest support.

An adjusting mechanism is provided for selectively setting a restoring force acting on a backrest of a chair. In a biasing unit of the adjusting mechanism, a spring segment is disposed between a head end and a follower end to bias the follower end to the remote position. The follower end is angularly movable on a cam surface between distal and proximate positions. In response to movement of a backrest of the chair from a normal position to an inclined position to permit the follower end to be forced by the cam surface to move from the remote position to a close position, two different restoring forces can be set by adjusting the follower end between the distal and proximate positions.

A device for adjusting the tilt of a chair backrest having a backrest frame rotatable with respect to the base frame of the chair is provided. The device includes elastic means for returning the backrest and/or countering the rotation thereof, in addition to means for controlling the preload of the elastic means. The means for controlling the preload include at least one first connecting rod and at least one first crank. The first connecting rod is hinged to the first crank and constrained to the elastic means so as to move the point of application of the returning and/or countering force with respect to the backrest. Adjusting means to adjust the position of the first crank determine at least two distinct stable positions of the first crank corresponding to two distinct positions of the mentioned point of application of the returning and/or countering force with respect to the base frame.