Abstract: The seat and pedestal of a chair are joined by a knee-tilt mechanism which includes a first support fixed to the underside of the seat adjacent the front edge thereof, and a second support fixed to the pedestal and having a sidewardly extending support tube arrangement. The first support has bearing hubs rotatably engaged with the support tube to define a horizontal tilt axis. A restoring mechanism is disposed within the second support for exerting a restoring torque about the tilt axis for urging the seat toward its horizontal position. The restoring mechanism, in the preferred embodiment, employs a sleevelike spring member of an elastomeric material disposed on the tilt axis for developing a restoring torque which generally linearly increases as the seat tilts away from the horizontal position. A second spring coacts between the supports for generating a second restoring torque which is additive with the first torque to effectively cause a torque dwell to facilitate tilting beyond an intermediate position.

Abstract: A load-released height-adjusting mechanism coacting between the relatively rotatable spindle and pedestal of a chair. The mechanism employs a split nut threadably engaged with the pedestal. A wedge is continuously spring-urged into engagement with the nut for urging the sectors thereof radially for engagement with the threaded pedestal. The wedge is loaded downwardly by the spindle when the chair seat is occupied to cause the nut sectors to lockingly and nonrotatably engage the pedestal to permit free rotation of the spindle without effecting height adjustment. The wedge is not acted on by the spindle when the latter is in a raised position due to the chair seat being unoccupied, but the frictional treaded engagement between the pedestal and nut prevents free-wheeling of the chair while permitting manual rotation of the chair seat and nut to effect height adjustment.