Device for converting a rotary motion into an axial motion

A device for converting a rotary motion into an axial motion, comprising:

• an outer tube with internal contours;
• an inner shaft having a head including external contours, the inner shaft having a central axis;
• an inner chamber formed between the tube and the shaft;
• several roller elements arranged in the inner chamber and around the head of the shaft, each roller element including at least one contour in active engagement with at least one of the internal contour of the tube and the external contour of the head, wherein the head and roller elements are axially displaceable relative to the tube essentially by rotation of the head relative to the roller elements during which the head remains essentially axially non-displaceable relative to the roller elements;
• a tubular element arranged coaxially with respect to the central axis of the shaft and being axially translational relative to the outer tube;
• and
• an elastic mechanism presenting a preset axial force biasing the shaft in a direction of the central axis relative to the tubular element such when the device is actuated for rotating the shaft relative to the outer tube, if the preset axial force of the elastic mechanism is overcome by a resistance against axial translation of the tubular element relative to the outer tube, the head of the shaft becomes actively engaged with the tubular element for purposes of force transmission.