Abstract: A (recliner) chair action of relatively movable seat frame (11), (back) drive frame (12) and yoke frame (13), with intervening links (16, 17, 18, 19), independently grouped respectively between seat frame and drive frame and between drive frame and yoke frame; for seat translation and elevation upon back recline operable under a potential energy function in an inter-relationship between back recline and seat movement, for a common or harmonious experience between different occupancy weights.

Abstract: A chair action features a movable seat frame (11), a drive frame (12) for effecting seat frame movement, and an underpinning yoke frame (13), intervening pivot slides operative between frames, with guideway slots (14, 14, 16) and followers (19) variously in frames, to contrive a combined pivot swing and translational slide action, and free-floating seat frame mobility, while conforming to virtual pivot geometry; operable under a potential energy function in an inter-relationship between back recline and seat movement, for a common or harmonious experience between different occupancy weights.

Abstract: A chair action features a movable seat frame (11), a drive frame (12) for effecting seat frame movement, and an underpinning yoke frame (13), intervening pivot slides operative between frames, with guideway slots (14, 14, 16) and followers (19) variously in frames, to contrive a combined pivot swing and translational slide action, and free-floating seat frame mobility, whilst conforming to virtual pivot geometry; operable under a potential energy function in an inter-relationship between back recline and seat movement, for a common or harmonious experience between different occupancy weights

Abstract: A (recliner) chair action of relatively movable seat frame (11), (back) drive frame (12) and yoke frame (13), with intervening links (16, 17, 18, 19), independently grouped respectively between seat frame and drive frame and between drive frame and yoke frame; for seat translation and elevation upon back recline operable under a potential energy function in an inter-relationship between back recline and seat movement, for a common or harmonious experience between different occupancy weights.

Abstract: A variable chair (10) features variable displacement between a back-to-seat pivot or slide pivot interconnection (14) and a back sliding pivot (15), to compensate for occupant weight in tilt moment in a weight responsive action; a particular construction features opposed pairs of intercoupled seat and back crank arm frames (111, 113) mounted upon a carrier or ground frame (114) by which the chair is supported, to achieve a back tilt, seat slide action; with the option of frame flex for restorative action; and with combined back and seat action about a virtual pivot which can approximate to a natural occupant body spine lumbar pivot and associated pivot movement path.