Abstract: A screw-nut screw coupling comprises a tubular element provided with an internal helical groove and an elongate member, formed by a preloaded spring having an external helical groove machined thereon. The tubular element is coupled to the elongate member by means of a number of balls mounted for rolling along an helical path defined by said helical grooves and forming a portion of an endless path for said balls to roll therealong. The tubular element is formed by at least two co-axial tubular sleeves rigidly connected to one another, one of said sleeves being arranged outside the other and being provided with groove means defining a portion of said endless path.

Abstract: A screw-nut screw transmission coupling in which a tubular outer innerly-grooved sleeve and an inner outerly-grooved elongate member are coupled to define a plurality of endless ducts for circulation of a plurality of ball bearings; each said endless duct being formed by two adjacent turns of a helical duct defined by said outer sleeve and said inner elongate member, and a return duct extending through a respective through bore provided through said sleeve and straddling said two adjacent turns, said return duct being defined by a cavity provided in a plate fixed to the outer surface of said sleeve and closing said through bore.

Abstract: A screw-nut screw transmission coupling with ball circulation of the type comprising a first elongated element and a second tubular element substantially coaxial to each other and with an external and an internal helical track respectively, is described. Said two tracks are disposed facing each other to define a helical rolling path for a plurality of balls disposed in mutual contact along said path and along a recirculation duct connecting the two ends of said path together, and said first element is constituted by an inner core and a metal strip wound in a cylindrical helix about and along said core, said strip being rigid with said core and having a cross-section which is concave outwards to define one of said helical tracks.

Abstract: A screw-nut screw coupling in which a tubular element provided with an inner helical groove is coupled to an elongate member provided with an outer helical groove by means of a number of balls mounted for rolling along an helical path defined by said helical grooves and forming a portion of an endless path for said balls to roll there along, said tubular element being formed by at least two co-axial tubular sleeves rigidly connected to one another, one of said sleeves being arranged outside the other and being provided with groove means defining a portion of the endless path and communicating with said helical path via at least one hole provided through the inner sleeve.