| 摘要 |
A landscape care tool can take the form of a vegetation-cutting tool incorporating circular-shaped blades having teeth or an earth-working tool incorporating hoeing tines. Drive linkage for such tool forms, as well as other tool forms, imparts linear movement in response to rotation of a shaft. The drive linkage includes a worm element which rotates with the shaft and a tooth carrier which moves linearly in response to rotation of the worm element. The worm element has one set of threads angled in one direction and a second set of threads angled in the opposite direction. The tooth carrier carries one tooth which engages threads of the first set of threads in order to move the carrier in one linear direction and a second tooth which engages threads of the second set of threads to move the carrier in the opposite linear direction. Variations in such characteristics as thread pitch spacing and pitch angle can be readily employed to substantially vary the characteristics of a drive assembly incorporating the linkage.
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