Wheelchair drive system

Abstract

A wheelchair drive system is described that operatively interposes a plural-speed hub subsystem between conventional rotatable hand wheels and their corresponding drive wheels, thereby providing wheelchair propulsion by rotary motion of the hand wheels and selective engagement of the drive wheels dependent upon a manually operated gear-shifting mechanism. Preferably, the hub subsystem includes symmetric left- and right-handed hubs each including a hub body fixedly connected with an easily accessible hand wheel, with the hub body rotating about a spindle fixedly mounted on the wheelchair and selectively gear-connectable to the drive wheel, the spindle being selectively connected to the drive wheel by the operation of a manually shiftable, plural-speed gear train. The gear train includes plural sets of planetary, sun and ring gears, with the sun gears mounted on the spindle, the ring gears formed along an inner surface of the hub body, and the planetary gears positioned along a mounting member that is shiftable lengthwise in parallel with the spindle's central axis. The mounting member is spring-biased against a first side of the hub body, with that member being shiftable against the spring's tension into alternative positions by a shift rod that extends along a central void formed within the spindle. The shift rod is positionable by manual operation of a shift bar connected therewith that extends outwardly of the wheelchair to a position of easy access by the wheelchair's user. A clutch and an active brake may be provided for smooth, at-speed shifting between plural speeds and for stopping.

Dependencies are inferred from the claim text.