Tension adjustment mechanism for a chair

摘要

A tilt control mechanism for an office chair includes a spring assembly therein which controls the tilt tension on the back assembly. This tilt control mechanism includes a tension adjustment assembly having a cam wedge which supports the legs of a pair of coil springs and a cooperating drive block assembly which cooperates with the cam wedge to drive the cam wedge upwardly and downwardly to vary the tilt tension. The drive assembly includes drive blocks mounted on a threaded shaft which are displaceable sidewardly toward and away from each other to either drive the cam wedge upwardly when the drive blocks move together or downwardly when the drive blocks move away from each other.