Reclining back wheelchair

Claim 1

In combination with a frame structure supporting a seat, a reclining back assembly including: a. back rest means pivoted at a first pivot point to said frame structure for movement from a generally upright position to a reclining position; b. an adjusting tube pivoted at one end at a second pivot point to the back rest means intermediate its lower and upper ends; c. a guide means in slidable engagement with the other end of the adjusting tube and pivoted at a third pivot point to the frame structure at a spaced point to the rear of said first pivot point; d. actuating linkage means coupled to said frame structure and manually movable to lock said back rest means relative to the seat, said guide means comprising a cylinder receiving said adjusting tube, said adjusting tube having a plurality of openings alone one longitudinal side, said actuating linkage means including a bell crank type bracket pivoted coaxially with said first pivot point and including fourth and fifth pivot points defining the vertices of a triangle with said first pivot point; e. a pawl member pivoted at said third pivot point and including a pawl juxtaposed the adjusting tube in a position to be received in and removed from a selected one of said openings upon rocking movement about said third pivot point and further including a sixth pivot point defining with said third pivot point and pawl the vertices of a second triangle; and f. a tie rod pivoted to said fifth and sixth pivot points, whereby rocking movement of said bell crank type bracket member moves said tie rod to thereby rock said pawl member in a direction to remove the pawl from an opening in said adjusting tube and permit the back rest means to be moved to a desired reclining position and locked in said position by rocking said bell crank type bracket member in an opposite direction to insert the pawl in a juxtaposed opening, the ratio of the distances between said first and fifth pivot points and the distance between said third and sixth pivot points being inversely proportional to the ratio of the angle through which said back rest means moves and and the angle through which said adjusting tube moves, so that the relationship between the pawl member and the guide cylinder remains substantially constant throughout reclining movements of said back rest means.