Linear rail bar with spacers

A linear-rail bar with spacers, said rail bar comprising:

• a track;
• a slider unit;
• a plurality of balls circulating between said track and said slider unit with a plurality of spacers of equal thickness and each interposed between two adjacent ones of said balls;
• said track comprises a rectangular shape having first grooves formed along surface thereof for said balls to roll there along;
• said slider unit includes a slider body and two end caps adapted for turning the moving direction of said balls, and second grooves corresponding to said first grooves are formed on said track along an inner surface of said slider body;
• said balls are accommodated between the first and second grooves of said track and said slider body, while said spacers are interposed between every adjacent ones of said balls;
• said balls comprise sphere balls of metallic material;
• said spacers comprise a cylindrical form comprising two truncated cone butts jointed with each other so that the diameter of a middle portion thereof is smaller than that at both ends thereof, and the diameter at both ends is smaller than that of said balls, and both ends are formed into inwardly concaved surfaces adapted for contacting said balls;
• a through hole extending through the inwardly concaved surfaces of each of the spacers;
• and
• wherein the minimum radius of curvature of a turning passage between the slider unit and the track is not smaller than that of the arcuate surface at the middle portion of said spacer.