Adjustable seat apparatus

Claim 1

SEAT STRUCTURE COMPRISING, IN COMBINATION: A FRAME HAVING A PAIR OF LATERALLY SPACED UPRIGHT BACK POSTS; A HORIZONTAL FULCRUM BAR BRIDGING BETWEEN SAID POSTS; A PAIR OF BRACKETS INCLUDING MEANS MOUNTED ON THE RESPECTIVE POSTS FOR VERTICAL ADJUSTMENT AND ARMS PROJECTING FORWARDLY FROM SAID MOUNTED MEANS; AND A BACK CUSHION HAVING AN UPPER PORTION THEREOF RESTING AGAINST SAID FULCRUM BAR AND HAVING, AT RESPECTIVE SIDES OF ITS LOWER PORTION, MEANS COOPERATING WITH SAID ARMS TO SUPPORT SAID BACK CUSHION ON SAID ARMS AT SELECTED POSITIONS OF FORE-AFT ADJUSTMENT OF SAID LOWER PORTION WHEREBY TO ADJUST SAID BACK CUSHION TO SELECTED POSITIONS; SAID CUSHION BEING FREELY SLIDABLE VERTICALLY WITH REFERENCE TO SAID FULCRUM BAR DURING VERTICAL ADJUSTMENT OF SAID BRACKETS ON SAID POSTS; SAID FULCRUM BAR BEING PROVIDED AT ITS RESPECTIVE ENDS WITH COLLARS ENCIRCLING THE RESPECTIVE POSTS AND VERTICALLY SLIDABLE THEREON; AND MANUALLY OPERABLE MEANS FOR LOCKING SAID COLLARS TO THE RESPECTIVE POSTS TO PROVIDE SELECTIVE POSITIONS OF VERTICAL ADJUSTMENT OF SAID FULCRUM BAR UPON SAID POSTS SO AS TO VARY THE HEIGHT OF FULCRUM SUPPORT OF SAID BACK CUSHION.