Patent ID: 6783180
Filing Date: 2004-08-31
Classification: A47C

Abstract:
An improved tilt lock device for a chair having a spindle member and piston for raising or lowering the chair, comprising:(a) a spindle housing mounted to said spindle member and piston where said spindle housing has a horizontal axis; (b) a pivot pin carried by said spindle housing and extending laterally with respect to said horizontal axis through said spindle housing; (c) a bracket member pivotally mounted to said pivot pin for rotation relative to said spindle housing; (d) a locking shaft having an axis of elongation slidably carried by said bracket member and by said spindle housing, said locking shaft extending laterally with respect to said horizontal axis through said spindle housing and at least in part through said bracket member where said locking shaft is responsive to external force for axial displacement and is so adapted for carriage by said spindle housing and said bracket member to permit slidable axial displacement of said locking shaft with respect to said axis of elongation upon the application of said external force; (e) a pawl plate for engagement with said piston for raising or lowering said chair having an upper surface and a lower surface where said pawl plate is fixed for rotation with said locking shaft and extends laterally to said axis of elongation; (f) a barrier rib disposed in said upper surface of said pawl plate and projecting above said upper surface, said barrier rib extending laterally with respect to said axis of elongation; (g) a pawl member carried by said pivot pin and mounted to permit rotation of said pawl member with respect to said pivot pin; and (h) a torsion spring carried by said pivot pin having a first extension and a second extension for compressively biasing both said pawl member and said pawl plate respectively so as to oppose rotation of said pawl plate, where said first extension compressively engages said pawl member and said second extension compressively engages said upper surface of said pawl plate thereby biasing said second extension against said barrier rib axially with respect to said axis of elongation whereby said locking shaft is precluded from axial displacement with respect to said axis of elongation without application of said external force applied to said locking shaft to overcome the bias of said second extension against said barrier rib.