| 摘要 |
A frictionless rear hub sprocket and ratchet assembly includes a sprocket fastened to the rear hub of the bicycle and coupled to the chain on the chain wheel of the bicycle, the sprocket having a plurality of internal teeth, a wheel concentrically disposed within an inner diameter of the sprocket, the wheel having equiangularly spaced pairs of stop elements, a ratchet mounted within the inner diameter of the wheel, and a plurality of pawls respectively pivoted to the wheel at one side and respectively disposed between two stop elements of each pair of the stop elements at the wheel, wherein when the sprocket does no work or is rotated clockwise, or when the ratchet does no work or is rotated counter-clockwise, the pawls do not engage the internal teeth of the sprocket and the external teeth of the ratchet, and the sprocket and the ratchet can be respectively rotated relative to each other; when the sprocket is rotated counter-clockwise or the ratchet is rotated clockwise, the pawls are respectively forced into engagement with the internal teeth of the sprocket and the external teeth of the ratchet, causing the ratchet and the sprocket to be rotated synchronously.
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