Chair.

摘要

A chair of the swivel and tilting type includes a seat (11) and back (12) supported on a pedestal with the seat and back being pivotal both rearwardly and forwardiy from a neutral position in which the seat is substantially horizontal. The principal pivot position (75, 76) for the seat in its relationship to the back is located on each side of the seat at substantially the ideal natural body pivot of the user which is somewhat above the seat and forward of the back. The back pivot (50) is located in the base (10) at the top of the pedestal and essentially vertically below such seat pivot, the link (58) supporting the back also supporting such seat pivotal support. The seat pivotal support may be rocked with the back supporting link fore and aft the neutral position. An L-shape seat cradle (78, 81, 88) is pivotaliy suspended from the pivotal support and forms one link of a four-bar linkage, the opposite end of the seat cradle being pivoted to a front link (92), in turn pivoted to a fixed link (10) or such base, as is the link (58) supporting the back. A pair of opposed springs (40, 41) hold the chair in the neutral position and readily return the chair to that position. The described four-bar linkage provides a rearward seat/back tilt ratio of about 1 to 3, and a more limited forward seat/back tilt ratio of approximately 1 to 2, respectively. The entire seat and back may be vertically adjusted, the back may be adjusted vertically with respect to the seat, and a spring loaded shoulder support (120) may be provided. The seat on its supporting link or cradle may be adjusted fore and aft to adjust seat depth. In addition, removable, height adjustable arm rests (17, 18) may be provided mounted on the pivotal supports, such arm rest being side-to-side interchangeable to widen or narrow the distance therebetween.