| 摘要 |
Disclosed herein is a lawn mower comprising a blade housing, a member adapted for rotation within the blade housing and having a peripheral edge, a blade movably secured to the member for movement between a retracted position wherein the blade is positioned inwardly of the peripheral edge, and an extended position wherein the blade extends outwardly beyond the peripheral edge, and a spring for biasing the blade to the retracted position in the absence of rotation of the member above a predetermined speed.
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