Torsion spring chair control

Claim 1

IN A CHAIR HAVING A BASE, POSTURE SUPPORT MEMBERS ATTACHED THERETO COMPRISING A CHAIR SEAT AND A CHAIR BACK AT LEAST ONE OF WHICH IS BACKWARDLY TILTABLE ABOUT A HORIZONTAL AXIS FROM A NORMAL POSITION AGAINST A STOP; A CHAIR CONTROL INCLUDING A FIRST FRAME MEMBER MOUNTABLE ON THE BASE AND A SECOND FRAME MEMBER ATTACHABLE TO THE TILTABLE POSTURE SUPPORT MEMBER AND PIVOTALLY CONNECTED TO THE FIRST MEMBER FOR BACKWARD TILTING MOVEMENT FROM THE NORMAL POSITION ABOUT THE AFORESAID HORIZONTAL AXIS, AND SPRING BIASING MEANS URGING THE MOVABLE POSTURE SUPPORTING MEMBER TO ITS NORMAL POSITION COMPRISING A TORSION SPRING CARRIED BY THE FRAME MEMBERS AND COILED AROUND THE SAID HORIZONTAL AXIS, SAID SPRING HAVING A FIRST END EXTENDING FROM ONE END TO SAID COIL AND SECURED TO THE FIRST FRAME MEMBER AND A SECOND END OF SAID SPRING EXTENDING FROM THE OTHER END OF SAID COIL AND BIASED AGAINST THE TILTABLE POSTURE SUPPORT MEMBER, SAID SPRING BEING TORSIONALLY LOADED UNDER THE INFLUENCE OF AN EXTERNAL FORCE EFFECTIVELY APPLIED TO TILT THE MOVABLE SUPPORT MEMBER MEANS RESTRAINING ECCENTRIC DISPLACEMENT OF THE COILS AND PROMOTING TORTIONAL BENDING OF THE SPRING UNDER LOAD, AND A STOP LIMITING THE BACKWARD TILT OF THE POSTURE MEMBER.