HEIGHT ADJUSTABLE ARM REST ASSEMBLY

A height adjustable arm rest assembly for use on a chair, the arm rest assembly includes a support member, an arm rest member, a locking mechanism attached to one of the support member and the arm rest member, and a substantially continuous engagement surface on the other of the support member and the arm rest member. The support member is attached to the chair and extends substantially upward therefrom. The arm rest member is movably attached to the support member and extends substantially coaxially therewith. The locking mechanism is attached to one of the support member and the arm rest member in order to secure the arm rest member in a selected vertical position relative to the support member. The locking mechanism includes an actuation member, a link connected to the actuation member, and a cam pivotably connected to the link. The cam has a front portion and a rear portion. The rear portion is received within a recess in one of the support member and the arm rest member. The recess is sized slightly larger than the rear portion of the cam in order to allow the cam to pivot about a generally horizontal axis through the rear of the cam. The cam is pivotable from a first position to a second position within the recess. A substantially continuous engagement surface is located on the other of the support member and the arm rest member.