A circular machine for knitting, hosiery or the like, with sinker actuation device, comprising: - a needle cylinder, arranged so that its axis is substantially vertical and actuatable with a rotary motion about said axis in both directions of rotation; said needle cylinder having, on its lateral surface, a plurality of axial grooves, each of which accommodates a needle that can move on command along the corresponding axial groove in order to pick up at least one yarn dispensed at at least one feed or drop and form knitting; - needle actuation cams, which face the lateral surface of the needle cylinder and define paths that are extended around the axis of the needle cylinder and can be engaged by at least one heel of the needles, which protrudes from the lateral surface of the needle cylinder, in order to actuate the movement of the needles along the corresponding axial groove with respect to the needle cylinder as a consequence of the rotation of the needle cylinder about its own axis with respect to said needle actuation cams and said at least one feed; - a sinker ring, which is integral with said needle cylinder in rotation about its own axis and is arranged coaxially to the needle cylinder at its upper end, said sinker ring supporting a plurality of sinkers that can move radially with respect to the needle cylinder and to the sinker ring; - a sinker cap, which is arranged above and coaxially with respect to said sinker ring and supports sinker actuation cams that define at least one path that is extended around the axis of the needle cylinder and can be engaged by a heel of the sinkers, which protrudes upwardly from said sinker ring, in order to actuate the movement of the sinkers along a radial direction with respect to the needle cylinder and to said sinker ring as a consequence of the rotation of the needle cylinder about its own axis with respect to said sinker cap, to said at least one feed and to said sinker actuation cams; said needle actuation cams comprising two needle lifting cams (45, 46), respectively a first cam for lifting the needles to the tuck or dropped position and a second cam for lifting the needles to the tuck or dropped position, which are arranged on mutually opposite sides with respect to an imaginary plane that passes through the axis of the needle cylinder and through said at least one feed or drop of the machine; said sinker actuation cams comprising two pusher cams (12, 13), respectively a first pusher cam and a second pusher cam, arranged on mutually opposite sides with respect to an imaginary plane that passes through the axis of the needle cylinder and through said at least one feed or drop of the machine; said pusher cams (12, 13) being able to engage said heel of the sinkers to cause the movement of said sinkers toward the axis of the needle cylinder; wherein said first pusher cam and said second pusher cam are arranged respectively at said first cam for lifting the needles to the tuck or dropped position and at said second cam for lifting the needles to the tuck or dropped position and can move with respect to the sinker cap toward or away from the axis of the needle cylinder, actuation means being provided which act on said first pusher cam and on said second pusher cam in order to move alternatively said first pusher cam or said second pusher cam toward the axis of the needle cylinder or away from the axis of the needle cylinder, characterized in that said first pusher cam and said second pusher cam can move on command with respect to said sinker cap from an inactive position, in which they are arranged at a preset distance from the axis of the needle cylinder, to a pusher position, in which they are arranged at a shorter distance from the axis of the needle cylinder with respect to said inactive position, and vice versa. - a needle cylinder, arranged so that its axis is substantially vertical and actuatable with a rotary motion about said axis in both directions of rotation; said needle cylinder having, on its lateral surface, a plurality of axial grooves, each of which accommodates a needle that can move on command along the corresponding axial groove in order to pick up at least one yarn dispensed at at least one feed or drop and form knitting; - needle actuation cams, which face the lateral surface of the needle cylinder and define paths that are extended around the axis of the needle cylinder and can be engaged by at least one heel of the needles, which protrudes from the lateral surface of the needle cylinder, in order to actuate the movement of the needles along the corresponding axial groove with respect to the needle cylinder as a consequence of the rotation of the needle cylinder about its own axis with respect to said needle actuation cams and said at least one feed; - a sinker ring, which is integral with said needle cylinder in rotation about its own axis and is arranged coaxially to the needle cylinder at its upper end, said sinker ring supporting a plurality of sinkers that can move radially with respect to the needle cylinder and to the sinker ring; - a sinker cap, which is arranged above and coaxially with respect to said sinker ring and supports sinker actuation cams that define at least one path that is extended around the axis of the needle cylinder and can be engaged by a heel of the sinkers, which protrudes upwardly from said sinker ring, in order to actuate the movement of the sinkers along a radial direction with respect to the needle cylinder and to said sinker ring as a consequence of the rotation of the needle cylinder about its own axis with respect to said sinker cap, to said at least one feed and to said sinker actuation cams;