Self-orientating twin castor of the type comprising a pair of coaxial wheels

A self-orientating twin castor comprising:

• a supporting body, having a substantially vertical wall;
• a slot, horizontally elongated and passing through said wall;
• a shaft, driven through said slot;
• a pair of wheels associated with the opposite ends of said shaft;
• a vertical receptacle, which is provided in said wall and is axially offset with respect to said shaft;
• a pivot, being rotatable in said receptacle for connecting the castor to a piece of furniture;
• two tubular portions, which protrude from opposite sides of said vertical wall and are substantially coaxial to said shaft;
• a substantially vertical hole, provided in said wall, above said slot and being connected thereto;
• a spring, accommodated in said hole and acting on said shaft;
• and a closure element which acts as an abutment for said spring, said hole being open upwards and closed by said closure element, two vertical ribs being provided inside each end of the tubular portions, a rim protruding inwards from a lower edge of said tubular portions, so as to trace a circular arc between said ribs, and wherein said closure element is constituted by a plug, rigidly coupled to a fairing, which is substantially concentric to said wheels.