| 摘要 |
A power assist device for use with a crank-operated drive mechanism including a pair of crank arms extending from opposite ends of a shaft mounted for rotation on a frame. The crank arms rotate the shaft about an axis with the crank arms revolving about the axis. The power assist device includes an energy storing mechanism mounted on the frame and operatively connected to the shaft for movement with the shaft. The energy storing mechanism stores energy during a first portion of a revolution of the crank arms, releases energy during a second portion of the revolution of the crank arms to assist in driving the rotation of the shaft, stores energy during a third portion of the revolution of the crank arms, and releases energy during a fourth portion of the revolution of the crank arms to assist in driving the rotation of the shaft.
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