Abstract: A ball screw has a spiral casing mounted coaxially with a shaft; a set of balls interposed between the shaft and the casing; and two seals fitted between the shaft and the casing to define, together with the shaft and the casing, a chamber for containing lubricant; each seal being defined by an annular member made of a first material having a first coefficient of thermal expansion, and by at least one insert located inside the annular member and made of a second material having a second coefficient of thermal expansion lower than the first coefficient.

Abstract: Ball screw with long duration and reduced noisiness, in particular for aerospace and industrial applications, comprising load-bearing balls made of ceramic material alternating, one by one, with spacer balls made of material having low volume mass, no greater than 3 g/cm3, and having a smaller diameter than that of the load-bearing balls.