A chair assembly includes an arm assembly that includes an armrest supported by a vertically adjustable support assembly and an arm base, where the arm base extends at an acute angle with respect to a longitudinal centerline of the chair assembly, an upholstery arrangement including a ring member attached to a cover, where the ring member includes a plurality of reliefs having a width that reduces as the ring member is wrapped about a shell member of the chair assembly, and a control arrangement having a biasing member that moves through an arcuate path as the biasing member is adjusted between varying bias settings.

A double shell seat includes a base for resting on a floor, an outer shell supported by the base, and an inner shell movably supported within the outer shell. The inner shell has a seat support, a backrest support, and a hinge between the seat support and the backrest support. The inner shell is movable with respect to the outer shell from an upright condition in which the seat support has a position toward the rear of the outer shell, the backrest support has a position that is relatively vertical, and the hinge is at a first angle, to a reclined condition in which the seat support is forward of its position in the upright condition, the backrest support is less vertical than its position in the upright condition, and the hinge is open at a greater angle than the first angle. The seat is preferably free of coil springs.

A chair includes a base structure, a seat support structure, a back frame comprising a front surface, a rear surface and a forwardly extending bottom portion pivotably connected to the base, a biasing member biasing the back frame from a reclined position toward an upright position, wherein the biasing member is located entirely forward a rearward most edge of the seat support structure, and a back shell comprising a forwardly extending bottom portion connected to the seat support structure, a front surface, a rear surface positioned in front of the front surface of the back frame, a pair of laterally spaced side portions defining an opening therebetween, and a top portion extending laterally between and connected to the side portions, wherein each of the side portions are exclusively connected to the back frame at a first location.

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).

A double shell seat includes a base for resting on a floor, an outer shell supported by the base, and an inner shell movably supported within the outer shell. The inner shell has a seat support, a backrest support, and a hinge between the seat support and the backrest support. The inner shell is movable with respect to the outer shell from an upright condition in which the seat support has a position toward the rear of the outer shell, the backrest support has a position that is relatively vertical, and the hinge is at a first angle, to a reclined condition in which the seat support is forward of its position in the upright condition, the backrest support is less vertical than its position in the upright condition, and the hinge is open at a greater angle than the first angle. The seat is preferably free of coil springs.

A reconfigurable apparatus for sitting and having a seat mounted on a frame and movable under the weight of a sitting user. As an incident of the user sitting, resistance to movement of a back rest component is increased a predetermined amount based upon the user's weight. A manually operable subassembly allows the increased resistance to be changed from the predetermined amount with the user sitting on the seat.

A chair according to the present invention has a reference position P located midway in a front-back direction in a movable range of a seat 2. The chair includes a return force generation mechanism 4 configured to generate a return force in a direction to return the seat 2 moved from the reference position P at least in the front-back direction to the reference position P. The return force generation mechanism 4 includes an elastic member 40 configured to increase the return force in the direction to return the seat to the reference position P as the amount of movement of the seat from the reference position P increases.

A chair includes a back member and arm brackets. The back member is tapered toward an end that is adjacent to a seat. The arm brackets are attached under a bottom portion of the seat. Each arm bracket is adjustable to provide a seat clearance area for the seat when one or more of the arm brackets are adjusted up to approximately 90 degrees from an original upright position.

A tilt-swivel chair employing a bearing base assembly in communication with connection plate or seat plate of the chair is provided. The tilting mechanism in forward and backward direction is provided by the spring which has a pushing and pulling action and the swiveling action is done along the side axis of the bearing base assembly, and the side axis is a cylindrical shape section with a bushing cap onto which a lever base is equipped and is connected to the connection plate or seat plate. The balance ball feeling is provided with the spring action. A cam and lever mechanism is provided at the base of the side axis in corporation with the base section of the assembly. The cam and lever mechanism provides a smooth swiveling action to the seat and to lock and shut down and take a break.

A reconfigurable apparatus for seating a user and having: a frame; a seat movable relative to the frame between: a) a first position in which the seat resides with no user sitting on the seat; and b) a loaded position; a back rest with a changeable angular orientation relative to the frame; and an adjusting assembly having a plurality of gears that move relative to each other as an incident of the seat moving from the first position into the loaded position to thereby cause an increase in resistance to changing of the angular orientation of the back rest.