| 摘要 |
<p>Apparatus (11) for cutting vegetation with a rotatable head (19) carrying a non-metallic cutting line (21) extended into a cutting plane. Additional line is extended from a supply line coil (39) within the head into the cutting plane without independent operator action. A mechanism in the head automatically feeds replacement line whenever the free end of the cutting line is reduced to less than a predetermined maximum length in the cutting plane. The cutting line length is always extended to this predetermined maximum length at all operational rotationals speeds, without adjustment, and in a positive step-by-step mode of segmental line advancement. The line feeder mechanism, has an escapement cam (56) with an off center pivotal mounting (46) that senses both centrifugal forces on the cutting line and changes in rotary speed of the head. </p> |
