A chair includes a seat and a backrest connected to a leg assembly. The front part of the seat is mounted on the leg assembly via a pivot link about an axis. The backrest is connected to the seat by a flexible intermediate part fixed to the leg assembly in the vicinity of the pivot of the seat for the purpose of a pivoting movement of the intermediate part by elastic deformation about an axis. The rear part of the seat is supported by the intermediate part, for example with at least one coupling element.

A chair includes a seat and a backrest connected to a leg assembly. The front part of the seat is mounted on the leg assembly via a pivot link about an axis. The backrest is connected to the seat by a flexible intermediate part fixed to the leg assembly in the vicinity of the pivot of the seat for the purpose of a pivoting movement of the intermediate part by elastic deformation about an axis. The rear part of the seat is supported by the intermediate part, for example with at least one coupling element.

An oscillation mechanism for a seat or a backrest of a chair or of an armchair is provided. The oscillation mechanism has a seat coupling, a backrest coupling, and a functional body made in a single piece of plastic material and consisting of a flexible unit portion, the functional body being elastically deformable by bending for the oscillation of the seat and of the backrest.

A seat support mechanism that is adapted to constrain motion of a bottom of a seat relative to a floor as the seat bottom moves up and down relative to the floor, where the seat has a seat back, and where the seat is constructed and arranged to support an occupant thereof above the floor, wherein the seat bottom has a front edge, and wherein the seat bottom supports the occupant's thighs with the knees in front of the front edge of the seat bottom. The seat support mechanism is constructed and arranged such that as the seat bottom is moved up and down, the seat support mechanism causes the seat bottom to pivot about a virtual lateral horizontal pivot axis located farther from the front edge of the seat bottom than the occupant's knees. The seat support mechanism is further constructed and arranged such that the back of the seat remains at a relatively constant angle to the floor as the seat bottom moves up and down and pivots.

A seating arrangement includes a base support, a support arrangement movable between upright and reclined positions, and a spring arrangement that includes a first portion attached to the support arrangement, a second portion attached to the base support, an intermediate portion positioned between the first and second positions, first and second members configured to bias the support arrangement from the reclined position toward the upright position, the second spring member spaced from the first spring member, and an adjustment member positioned between the first and intermediate portions, the adjustment member adjustable between positions that adjust the force exerted by the first and second spring on the support arrangement.

An adjustment device for a chair with an oscillating mechanism having a first plate, connected to a central gas-operated post for height adjustment of a seat, to which a second plate, fixed to a backrest, is articulated so that the second plate can oscillate by means of a first pivot, wherein a third plate is articulated and interposed, respectively by means of a second pivot and a third pivot, between said first plate and said second plate, and is configured to be connected to said seat, said first plate having means for connection to at least one slat or leaf spring which is adapted to contrast to an inclination of said second plate with respect to said first plate.

A seat, such as a chair or stool, is disclosed and comprises a frame including at least one leg, an undercarriage which is configured to receive the leg, and a seat pan. The seat pan is rotatably mounted to the undercarriage, wherein the seat pan is rotatable about an axis of rotation relative to the undercarriage. The undercarriage also includes a recess and a resilient component in the recess, while the seat pan includes a stop located on a bottom surface of the seat pan. On rotation of the seat pan relative to the undercarriage, such as may occur when the person seated leans forward or back, the resilient component is compressed between the undercarriage and the stop. In one embodiment, an axle passes through the axis of rotation and connects the legs, and potentially backrest if present, to the undercarriage.