Abstract: A mechanism for connection to a chair and to a base for allowing the chair to tilt forward and backward and from side-to-side relative to the base when the base is supported on a floor. The mechanism includes a support in the form of a housing mounted on a base by horizontal pin for forward and backward tilting movement on the base. A plate is mounted on the support for pivotal movement from side-to-side, the plate adapted to be coupled to the underside of the chair. A pair of torsion bars is carried by the support and serves to exert a spring bias force on the support when the chair is tilted backwardly relative to the base. The two torsion bars can be coupled in a manner to limit the spring bias effect of one of the torsion bars so that adjustments in the spring loading can be made as to the size and weight of a person sitting in the chair.