Synchrotilt chair

A synchrotilt mechanism for a chair to provide improved control over the relative but synchronized tilting of the back and seat during tilting. The chair back is supported on a rigid upright assembly including lower lever arms which project under the chair seat and are coupled at forward ends to a horizontal tilt shaft which is disposed under the front of the chair seat and is supported on a control housing fixed to the upper end of the base pedestal. A tension control mechanism is coupled between the tilt shaft and the control housing for normally urging the upright arrangement, and the chair back, into an upright position. The chair seat is movably supported on the lower lever arms by a support arrangement which permits the chair seat to pivot relative to the upright assembly about a generally transverse horizontal axis which is preferably slightly below the upper surface of the seat when the latter is in a nondeformed condition, i.e., the seat is not occupied. A control mechanism is coupled between the control housing, the upright assembly and the seat frame to permit synchronized tilting of the seat relative to the back in response to tilting of the back about the axis of the tilt shaft.