| 摘要 |
A crutch has a piston 3 and cylinder 2 arrangement connected through a manually controlled valve (30, 54) and two one way ball valves 22,24 to a reservoir 12. A working fluid partly liquid and partly gas is compressed in the reservoir 12 and by manipulating the valve 30, 54 the user shortens the crutch by applying force between the handle 15 and the tip 5 and further manipulation of the valve 30,54 permits the liquid to resist shortening of the crutch.
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