Patent ID: 8376463

Claim:
A backrest angle adjustable mechanism for attachment of a backrest to a wheelchair tubing comprising, a tubing attachment bracket being capable of attachment to the wheelchair tubing, wherein the tubing attachment bracket includes a center line along a common longitudinal axis; a rod connected to the tubing attachment bracket, wherein the rod includes a through-bore of varying diameter to form a shoulder at a distal end; a screw disposed in the through-bore of the rod; wherein a distal end of the screw extends out the distal end of the rod when assembled therein, wherein a proximal end of the screw includes a shoulder larger than a through-bore diameter at the distal end of the rod; a biasing device entrapped between the shoulder of the screw and the shoulder of the rod, wherein the rod, the screw, and the biasing devise have an axial center line along the common longitudinal axis, wherein the screw is biased along the common longitudinal axis when the screw is further extended out of the distal end of the rod, a pivot bar pivotably connected to the tubing attachment bracket and attachable to the backrest, wherein the pivot bar rotates around the common longitudinal axis; an inner gear having a center line along the common longitudinal axis, wherein the inner gear is attached to the pivot bar to form a pivotal assembly, wherein the inner gear includes one or more male gear teeth; a cover having a center line along the common longitudinal axis; wherein the cover includes a plurality of internal female gear teeth that cooperate with the one or more male gear teeth of the inner gear to lock an angular position of the backrest; wherein the cover is attached to the distal end of the screw for repeated longitudinal traverse cycles along the common longitudinal axis; and wherein, the backrest is free to rotate about the common longitudinal axis when the cover is longitudinally traversed away from the inner gear to disengage the one or more male teeth of the inner gear from the plurality of internal female gear teeth of the cover.