Abstract: The cutting blades of an electrically driven mincing machine are carried by a sleeve which fits over a driving element at the top of a vertical motor-driven shaft. The sleeve and driving element are provided internally and externally respectively with driving ramps which extend helically from bottom to top thereof in the direction of rotation of the driving element and which have active surfaces which engage one with the other during driving of the sleeve. The sleeve and driving element are also provided internally and externally respectively with retaining ramps which extend helically from bottom to top thereof in a direction opposite the direction of rotation of the driving element and which have active surfaces engageable one with the other where the driving element stops rotating thereby to prevent escape of the sleeve in an upward direction.