Adjustable chair

Claim 1

An adjustable chair comprising a base, a telescopic column on the base supporting a seat, the seat having a rigid outer frame divided into two sections hinged together, a front section of which being mounted on said column and a rear section of which being able to tilt relatively to said front section, there being an adjustable, resilient supporting means positioned and acting between said two sections, and said rear section of the frame supporting in a pivotal manner a seat back, so that the seat back can tilt relatively to said frame, and there being an adjustable resilient means positioned and acting between said seat back and said frame, said supporting means comprising a cylindrical guide element which has one end pivotably mounted on said front section of the frame and its other end slidably engaged in an externally threaded sleeve which is screwed into a pivot means itself supported on said rear frame section so as to be able to pivot therewith, there being a lock nut mounted on said sleeve in such a way as to afford rotation of said sleeve in said pivot means, and a spring inserted between said lock nut and the end of said guide element that is mounted on said front section of said frame, said chair further comprising a bar supported such that it can rotate at one end thereof on said pivot means and has a slot at the other end thereof, a pivot pin pivotably mounting said guide element to said front frame section being inserted into said slot, said slot being profiled so as to house said pivot pin in two positions, one position affording a longitudinal stroke of the pivot pin in the slot corresponding to compression in the spring, and the other position preventing this stroke, with means provided to set and maintain said bar in one or other of said positions.