Height adjustment mechanism for a chair

Abstract

A height adjustment mechanism 10 for a chair is arranged to raise and lower a seat platform 14 of the chair relative to a base 12 of the chair. The mechanism comprises a four-bar linkage 30 comprising a fixed base link 32 connectable to the base of the chair, a coupler 60, and first 44 and second 46 wishbone linkages pivotally connected between the base link and the coupler. The mechanism further comprises a front seat linkage 72 fixedly connected to said platform and pivotally connected at a first seat pivot 69 to an arm 48 of the first wishbone linkage extending from the four-bar linkage, and a rear seat linkage 74 fixedly connected to said seat platform and pivotally connected at a second seat pivot 71 to an arm 54 of the second wishbone linkage extending from the four-bar linkage. During movement, a plane containing the seat pivots remains parallel to an axis of the fixed base link such that, in use, an angle between a plane of the seat platform and the axis of the fixed base link does not change. A method of adjusting the height of a seat platform of a chair is also disclosed.

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