Circular knitting machine for hosiery or the like

A circular knitting machine for hosiery or the like, comprising at least one needle cylinder which has a vertical axis and has, on its lateral surface, axial slots, each of which accommodates a needle and a needle actuation element;

• said actuation element being engageable, with one of its ends, with the needle arranged in the same axial slot;
• said needle or said actuation element being provided with at least one fixed heel, which protrudes radially from the lateral surface of the needle cylinder to engage actuation cams, which are arranged around the lateral surface of the needle cylinder and define paths which can be traced by said fixed heel as a consequence of the actuation of said needle cylinder with a rotary motion about its own axis with respect to said actuation cams, wherein said actuation element is provided with a heel which can move on command from an active position, in which it protrudes radially from the corresponding axial slot of the needle cylinder so as to engage said actuation cams, to an inactive position, in which it is contained in said axial slot of the needle cylinder so as to not engage said actuation cams, and vice versa, and in that said actuation cams comprise, at at least one feed or drop of the machine:
• an extraction cam, a retraction cam and a knockover cam, arranged sequentially along the direction of rotation of the needle cylinder with respect to said actuation cams;
• said extraction cam being always engageable by said fixed heel to produce the movement of the corresponding needle into an extracted off-work position;
• said retraction cam being engageable exclusively by said movable heel in the active position in order to move said needle or said actuation element to such a level as to engage, with its fixed heel, said knockover cam, which causes the transfer of the corresponding needle from the extracted off-work position to the retracted position for forming a new loop of knitting, with lowering of the previously formed loop of knitting.