Abstract: Apparatus for cutting vegetation with a rotatable head carrying a non-metallic cutting line extended into a cutting plane. As the line extension decreases from an established preset length an actuator in the head permits additional line to be extended automatically from a supply source within the head. The actuator imposes a back pressure against the line of magnitude correlated to the sensed pull tension wanting to extend the line outward of the head. After the cutting line length is extended to its restored original preset length, the actuator in response to the operational forces imposed thereon secures the cutting line against further extension until a subsequent decrease in line extension is incurred. In one embodiment an inertial drag brake is activated during the course of line feedout and is deactivated after the length of cutting line has been fully restored.

Abstract: Apparatus for cutting vegetation with a rotatable head carrying a non-metallic cutting line extended into a cutting plane. Additional line is extended from a supply line coil within the head into the cutting plane without independent operation action. A mechanism in the head feeds a certain incremental length of line whenever the free end of the cutting line is reduced to this length by wear, or otherwise. After the cutting line length is extended to its original preset length, the cutting line is secured automatically against further extension from the head. The incremental line feeder mechanism is actuated by sensing an operating condition of the head, e.g., angular velocity of rotation.

Abstract: Apparatus for cutting vegetation with a rotatable head carrying a non-metallic cutting line extended into a cutting plane. As the line extension decreases from an established preset length an actuator in the head permits additional line to be extended automatically from a supply source within the head. The actuator imposes a back pressure against the line of magnitude correlated to the sensed pull tension wanting to extend the line outward of the head. After the cutting line length is extended to its restored original preset length, the actuator in response to the operational forces imposed thereon secures the cutting line against further extension until a subsequent decrease in line extension is incurred. In one embodiment an inertial drag brake is activated during the course of line feedout and is deactivated after the length of cutting line has been fully restored.

Abstract: Apparatus for cutting vegetation with a rotatable head carrying a non-metallic cutting line extended into a cutting plane. Additional line is extended from a supply line coil 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 irrespective of the length of cutting line being lost to wear or breakage. The line feeder mechanism is actuated by sensing an operating condition of the head, e.g., angular velocity of rotation.