| 摘要 |
A wheelchair drive system that operatively interposes a plural-speed hub subsystem (26) between conventional rotatable hand wheels (18, 20) and their corresponding drive wheel (14, 16), thereby providing wheelchair propulsion by rotary motion of the hand wheels (18, 20) and selective engagement of the drive wheels (14, 16) dependent upon a manually operated gear-shifting mechanism (22). Preferably, the hub subsystem (26) includes symmetric left-handed hubs (28) and right-handed hubs (26), each including a hub body fixedly connected with an easily accessible hand wheel, with the hub rotating about a spindle (84) fixedly mounted on the wheelchair and selectively gear-connectable to the drive wheel, the spindle (84) being selectively connected to the drive wheel by the operation of a manually shiftable, plural-speed gear train (Figures 3, 4, 5). The gear train includes plural sets of planetary (72), sun (56) and ring gears (68, 78), formed along an inner surface of the hub, and the planetary gears (72) positioned along a mounted member (62) that is shiftable lengthwise in parallel with the spindle's central axis. The mounting member (62) is spring-biased (82) against a first side of the hub, with that member being shiftable against spring's tension into alternative positions by a shift rod (34) that extends along a central void formed within the spindle. The shift rod (34) is positionable by manual operation of a shift bar (24) connected therewith that extends outwardly of the wheelchair to a position of easy access by the wheelchair's user. |
