| 摘要 |
An apparatus for cutting vegetation with a rotating head carrying a flexible, non-metallic cutting line extended radially into a cutting plane. An additional length of line is extended into the cutting plane automatically during rotation of the head as its speed increases from a first magnitude to a second magnitude. A laterally displaced cam within the head moves outwardly for releasing a spool carrying coiled cutting line to advance a first angular displacement within the head. The spool rotates a second angular displacement to return the cam to its original position by the drag of the cutting line during vegetation cutting but not by free air travel. After the cutting line length extension is completed, the spool is secured by the cam at its initial position automatically against further rotation within the head.
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