A floor tile levelling system; comprising: - a separation post incorporating: a base component; a separator component; and a threaded shaft extending from an upper portion of said separator component; and - a threaded cap incorporating: a hollow body provided with a lower cylindrical component; an upper hub axially centred with respect to the lower component; a series of lateral openings; and a plurality of ribs arranged between said lateral openings and extending from the lower cylindrical component to the upper hub; - wherein said upper hub has a female thread for the assembly of the cap on the threaded shaft of the separation post and the tightening of the cap against an upper surface of the floor tiles being levelled; - the hollow body of the cap has a dome-shaped curved convex outer surface defined by the ribs; - said ribs have a substantially U-shaped structural cross-section, and comprise: - a first wing that extends from said first lateral end of the web toward the interior of the cap and forming inside the corresponding opening a first curved concave surface for exerting pressure on the cap in the direction of rotation corresponding to the tightening of the cap on the threaded shaft; characterised in that said ribs further comprise: - a smooth external web with no outwards protruding wings or extensions, said external web having an increasing width in a downward direction toward a first lateral end thereof with a curved concave profile; and - a second wing that extends from a second lateral end of the web of the rib toward the interior of the cap and forming inside the corresponding opening a substantially vertical surface for exerting pressure on the cap in the direction of rotation corresponding to the loosening of the cap on the threaded shaft. - a separation post incorporating: a base component; a separator component; and a threaded shaft extending from an upper portion of said separator component; and - a threaded cap incorporating: a hollow body provided with a lower cylindrical component; an upper hub axially centred with respect to the lower component; a series of lateral openings; and a plurality of ribs arranged between said lateral openings and extending from the lower cylindrical component to the upper hub; - wherein said upper hub has a female thread for the assembly of the cap on the threaded shaft of the separation post and the tightening of the cap against an upper surface of the floor tiles being levelled; - the hollow body of the cap has a dome-shaped curved convex outer surface defined by the ribs; - said ribs have a substantially U-shaped structural cross-section, and comprise: - a first wing that extends from said first lateral end of the web toward the interior of the cap and forming inside the corresponding opening a first curved concave surface for exerting pressure on the cap in the direction of rotation corresponding to the tightening of the cap on the threaded shaft; characterised in that said ribs further comprise: - a smooth external web with no outwards protruding wings or extensions, said external web having an increasing width in a downward direction toward a first lateral end thereof with a curved concave profile; and - a second wing that extends from a second lateral end of the web of the rib toward the interior of the cap and forming inside the corresponding opening a substantially vertical surface for exerting pressure on the cap in the direction of rotation corresponding to the loosening of the cap on the threaded shaft. - a first wing that extends from said first lateral end of the web toward the interior of the cap and forming inside the corresponding opening a first curved concave surface for exerting pressure on the cap in the direction of rotation corresponding to the tightening of the cap on the threaded shaft; characterised in that said ribs further comprise: - a smooth external web with no outwards protruding wings or extensions, said external web having an increasing width in a downward direction toward a first lateral end thereof with a curved concave profile; and - a second wing that extends from a second lateral end of the web of the rib toward the interior of the cap and forming inside the corresponding opening a substantially vertical surface for exerting pressure on the cap in the direction of rotation corresponding to the loosening of the cap on the threaded shaft. - a smooth external web with no outwards protruding wings or extensions, said external web having an increasing width in a downward direction toward a first lateral end thereof with a curved concave profile; and - a second wing that extends from a second lateral end of the web of the rib toward the interior of the cap and forming inside the corresponding opening a substantially vertical surface for exerting pressure on the cap in the direction of rotation corresponding to the loosening of the cap on the threaded shaft.