A ball screw device includes an elongated shaft having an outer groove, a ball nut having a screw hole for receiving the elongated shaft and having a passage communicating with the screw hole of the ball nut, and a lubricating device includes an inner cylindrical element engaged onto the elongated shaft and secured to the ball nut, a housing attached onto the cylindrical element and contacted with the ball nut, and the housing includes a chamber for receiving a lubricating grease, an oil distributing member is engaged into the passage of the ball nut and engaged into the screw hole of the ball nut for engaging with the elongated shaft, and an inner element is engaged in the housing and engaged with the distributing member for supplying the lubricating grease to the distributing member.

A two-phase structured lubricant includes a liquid component about 5% by weight (wt. %) to 95 wt. %, and a structural component about 5 wt. % to 95 wt. %. The structural component recrystallizes or solidifies around the liquid component.

A bearing includes a first member having a passageway configured to engage a shaft, the first member having a metallic material; and a second member disposed around at least a portion of the first member, the second member having a metallic material and at least one radially and inwardly bent portion capable of restricting axial movement of the first member. The first and second members are movable relative to each other.