| 摘要 |
An armrest-driven wheelchair propelled forwards and backwards by the armrests thereof through two ratchet wheel mechanisms, wherein each ratchet wheel mechanism includes a casing having one end coupled to one armrest by a connecting bar and an opposite end fixedly mounted with a ratchet wheel, which is fixedly mounted around one end of the wheel shaft of the wheels of the wheelchair, a triangular steering control block turned between a first position and a second position, an upper pawl member and a lower pawl member respectively supported on a respective spring and disposed at two opposite sides relative to the steering control block and alternatively forced by the steering control block into engagement with the ratchet wheel to limit the rotary motion of the ratchet wheel in the forwards or backwards direction.
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