| 摘要 |
A wheel assembly for a wheelchair having a two-gear arrangement, in which a hypocycloidal gear provides a ratio lower than 1:1. A shift member (38), located on the wheel assembly, has hand operated shift portions (70, 72) and is capable of moving perpendicular to the wheel axle between two positions. The shift member can be moved while the user is seated in the wheelchair and the wheelchair is not moving. The wheel assembly includes a hand rim (14) connected to a housing (18) within which is a gear assembly (22). The gear assembly includes two spaced cage plates (86, 88) which are joined by fixed shafts (92A-92A) having unidirectional rollers (92, 92) positioned thereon around the periphery thereof. The rollers have an exterior surface portion which engages with the interior surface of the housing to readily permit movement in the forward direction, but to prevent movement in the rear direction, unless the hand rims are used to rotate the housing relative to the gear assembly. The cage plate has rubbing elements which interact with the interior surface of the housing to produce an additional braking force for downhill terrain. |
