A trimmer head, comprising: a casing 21,22, a supporting device 31,32 for a cutting wire spool, which supporting device (31,32) is arranged within the casing (21,22) and movable between an engagement position, wherein it is rotatingly solid with the casing (21,22), and a free position, wherein it is not rotatingly solid with the casing (21,22). The head further comprises coupling means 41,42, which are so configured as to make the casing (21,22) and the supporting device (31,32) rotatingly solid with one another in the engagement position, engagement means (43) which are so configured as to allow displacement of the supporting device (31,32) from the free position to the engagement position and release means (51,52) configured for moving the supporting device (31) from the engagement position to the free position, said release means (51,52) being activated under the effect of the centrifugal force due to rotation of the trimmer head. The supporting device 31 comprises a lower disk (31) and an upper disk (32) which are independent of one another.
