Abstract: The invention deals with the field of screwing heads for small trigger-type pumps or triggers and namely for applying, on vessels, triggers equipped with a threaded securing ring nut (2). This screwing head (1) is rotated around a vertical axis through a permanent magnet-type clutch and comprises four rollers (5) which tighten the toothed ring nut (2) when screwing it; said rollers (5) are supported by vertical arms (4) whose axes are arranged at 90° one from the other on a circumference with its center on the rotation axis of the screwing head. The vertical arms (4) and the four rollers (5) are simultaneously carried along a radial direction towards said ring nut through an oscillating movement.