| 摘要 |
<p>Cutting filament metering apparatus for a flexible filament vegetation cutting device in which a flexible filament cutting element is coiled on a filament holder rotatably driven about a substantially vertical axis with a free end of the driven filament defining a cutting plane. The cutting filament metering apparatus includes a driver element rotatably driven about a substantially vertical axis and an engagement member carried by the filament holder for driving engagement with the driver element. An escapement device is also secured to the filament holder and allows limited rotational movement of the holder with respect to the driver element to release a predetermined length of cutting filament. The filament holder is axially biased into a first position in which the driver element engages the engagement device. In one embodiment, the engagement and escapement devices are annular each having teeth circumferentially disposed and projecting radially inward toward the driver axis of rotation. The driver element is provided with driving teeth circumferentially disposed and projecting radially outward from the driver axis of rotaton to alternately engage either the teeth on the engagement or escapement devices. Additionally, in certain embodiments, a housing is provided which partially encloses the cutting plane defined by the driven cutting filament and a cutting blade is attached to the housing at the outer periphery of the cutting plane. The cutting blade severs excessive flexible filament to maintain the filament length at a predetermined maximum.</p> |
