Grass-cutting head with cutting line with cutting line refilling without opening

A grass-cutting head with cutting line, the grass-cutting head comprising:

• an outer housing;
• a spool housed in the outer housing, the spool comprising a central body with a rotation axis, about which a cutting line is wound, an axial cavity in the central body, into which an insert for mechanical coupling of the head to a motor shaft can be introduced, two opposite cutting line insertion channels, each of said two opposite cutting line insertion channels extending approximately radially from a respective first opening toward a respective second opening positioned in the axial cavity;
• a compression spring arranged inside the housing and substantially coaxial to the spool, which elastically biases the spool with respect to the housing;
• at least two bushings in approximately diametrically opposite positions in a lateral wall of the outer housing, said bushings being alignable with the first openings of the two opposite cutting line insertion channels, wherein in the axial cavity of the spool two opposite projections for supporting the spring are formed, forming pairs of lead-in and guide surfaces converging toward the respective second openings of the two opposite cutting line insertion channels.