Abstract: A chair assembly includes a four-bar linkage assembly including a first linkage member, a second linkage member, a third linkage member and a fourth linkage member each pivotably coupled to one another such that the four-bar linkage assembly includes an upper end that is adjustable between raised and lowered positions, and an arm rest assembly adapted to support the arm of a seated user thereon and supported the upper end of the four-bar linkage assembly, wherein a lower end of the four-bar linkage assembly is pivotably supported from an arm support structure for pivotable movement, such that the upper end of the four-bar linkage assembly is moveable between a first position and second position located laterally outward from the first position.

Abstract: A chair assembly includes a four-bar linkage assembly including a first linkage member and a second linkage member each having a U-shaped cross-sectional configuration that cooperate to form an interior space, a third linkage member and a fourth linkage member, wherein the linkage members are pivotably coupled to on another such that an upper end of the four-bar linkage is vertically adjustable between a raised and lowered positions, an arm rest assembly supported on the upper end of the four-bar linkage assembly, and a locking assembly including a first locking link having a first surface and a second locking link having plurality of teeth corresponding to a plurality of vertical positions of the four-bar link located between the raised and lowered positions, wherein the locking links are movable between locked and unlocked positions, and wherein the first and second locking links are located within the interior space.