Power seat slide device

A seat slide device comprising:

• a stationary rail including
• a first bottom wall portion, first and second inside wall portions vertically upwardly extending from respective side ends of said first bottom wall portion, first and second upper wall portions outwardly extending from upper ends of said first and second inside wall portions, respectively, and first and second outside wall portions vertically downwardly extending from outer ends of said first and second upper wall portions, respectively,
• each of said first and second upper wall portions being grooved at a major portion thereof for receiving ball bearings thereon and being convexly curved at a rear end portion thereof in a plane perpendicular to a longitudinal axis of said stationary rail, said major portion and said rear end portion being united,
• said rear end portion being higher than said major portion such that said rear end portion overlaps with one of said ball bearings with respect to a direction along said longitudinal axis of said stationary rail and serves as a stopper of the sliding movement of said one of said ball bearings on said major portion;
• a movable rail axially slidably engaged with said stationary rail, said movable rail including
• an upper wall portion, first and second movable rail outside wall portions vertically downwardly extending from respective side ends of said upper wall portion, first and second movable rail bottom wall portions inwardly horizontally extending from lower ends of said first and second movable rail outside wall portions, respectively, and first and second movable rail inside wall portions vertically upwardly extending from inner ends of said first and second movable rail bottom wall portions, respectively;
• a front bracket secured to a front end portion of said bottom wall portion of said stationary rail;
• and
• a rear bracket secured to a rear end portion of said bottom wall portion of said stationary rail through at least one bolt;
• wherein said stationary and movable rails are so assembled that said first movable rail inside wall portion is disposed between said first inside wall portion of said stationary rail and said first outside wall portion of said stationary rail, and said second movable rail inside wall portion is disposed between said second inside wall portion of said stationary rail and said second outside wall portion of said stationary rail;
• wherein a front end of said convexly curved rear end portion is positioned ahead of said at least one bolt with respect to said direction along said longitudinal axis of said stationary rail.