| 摘要 |
An improved earth-working tool including a disc having a central portion and an outer peripheral portion. The disc is rotatable about a substantially horizontal a xis extending through the central portion. A peripheral portion has a plurality of first points al ong the outer peripheral portion which are closer to the axis than other points on the outer peripher al portion. The first points are substantially equidistantly spaced from the axis. Radially inner sections of the outer peripheral portion are disposed along a line which is substantially tangenti al to an arc formed around the axis of rotation and through the first points, whereby the substa ntially tangential sections will tend to cut residue on top of the soil in a more downward dire ction than conventional circular discs do. The discs also have radially outer sections on the outer peripheral portion which are not along the substantially tangential lines and which are further from the axis than the first points. An alternate embodiment has an outer periphery with a lternating radially inward and radially outward arcuate sections, the inward arcuate sections be ing longer than the outer sections.
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