| 摘要 |
A wheelchair includes a seat that pivots forward to assist the user in exiting and entering the chair. The seat is biased toward its forward or up-right position by mechanical springs having force adjustments for user adjustment of the seat-lift force. One embodiment includes a cam mechanism for varying this seat-lift force as the seat is being raised. A closed-loop hydraulic cylinder and piston actuator system is provided to (1) damp the spring action as the seat is raised and lowered, (2) control the rate of seat ascent and descent, and (3) permit the user to stop and lock the seat in any position between the horizontal and up-right positions. This closed-loop hydraulic system includes a manual control valve for user-control of the seat raising and lowering, and a user-adjustable flow rate control valve for limiting seat ascent and descent speeds.
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