Back support adjustment for torsion chair

Claim 1

AN ADJUSTABLE TORSION BACK CHAIR COMPRISING IN COMBINATION: A SEAT FRAME HAVING A PAIR OF INTERCONNECTED OPPOSITE SIDE PORTIONS; A SUBSTANTIALLY RIGID AN INFLEXIBLE SUPPORT CHANNEL POSITIONED CENTRALLY BETWEEN SAID SIDE PORTIONS AND EXTENDING TOWARD THE BACK OF SAID FRAME; A TORSION BAR BETWEEN SAID CHANNEL AND SAID SIDE PORTIONS; SAID TORSION BAR FIXEDLY CONNECTED TO SAID SUPPORT CHANNEL AND TO SAID SIDE PORTIONS TO SUPPORT THE SAID CHANNEL AND PROVIDE LIMITED TORSIONAL RESILIENCE THERETO; A SECOND CHANNEL MEMBER LARGER IN CROSS-SECTION THAN SAID SUPPORT CHANNEL INTERFITTED BENEATH THE SAID EXTENDING PORTION OF THE LATTER AND FIXEDLY SECURED THERETO TO DEFINE THEREWITH A REARWARDLY OPENING HORIZONTAL SLOT; AN LSHAPED RESILIENT BACK SUPPORT HAVING A LOWER LEG PORTION; SAID LOWER LEG PORTION SLIDABLY ENGAGED IN SAID SLOT; A THREADED APERTURE FORMED IN SAID LOWER LEG PORTION; AN ELONGATED APERTURE FORMED IN SAID SECOND CHANNEL; AND TURN SCREW LOCKING MEANS PASSING THROUGH EACH OF SAID APERTURES AND ENGAGING SAID THREADS; SAID LOCKING MEANS AND ELONGATED APERTURE PROVIDING FOR POSITION ADJUSTMENT OF SAID BACK SUPPORT; AND SAID LOCKING MEANS WHEN TIGHTENED IN SAID THREADS DRAWING SAID LEG PORTION AND SECOND CHANNEL MEMBER INTO BEARING RELATIONSHIP TO THEREBY LOCK THE SAME TOGETHER TO SECURE SAID BACK PORTION IN A DESIRED ADJUSTED POSITION.