| 摘要 |
A self propelled wheel chair is adaptable to climbing and descending stairs and steep slopes. The wheel chair is foldable for transporting and storing. Operation on level ground is similar to the operation of a conventional wheel chair. The wheel chair is supported by caster wheels on the front corners and by spider wheels on the rear corners. Skids are mounted to the caster forks for stabilizing the front of the chair during climbing operations. The casters are mounted to parallelogram linkages on the front of the wheel chair. The parallelogram linkages move the casters down and forward for repositioning to the climbing mode. The spider wheels are rotatably mounted to four bar linkages on the wheel chair side frames. The spider wheels engage the stairs to propel and stabilize the wheel chair during climbing or descending of stairs. The four bar linkages sequence the repositioning of the spider wheels and casters for climbing. Weight is shifted to the spider wheels for climbing so that they can provide climbing forces without slipping. Propulsion and transition control and power are provided by individual hand wheels linked by chain drives to the spider wheels and transition linkages. Propulsion power for both conventional level operation and stair climbing operation is transmitted through the same hand wheels and spider wheels. The hand wheels are grounded to the wheel chair structure by no back brakes to brake the wheel chair linkages and spider wheels in place when the hand wheels are released by the passenger.
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