Linear motion guide device and end cap for linear motion guide device

A linear motion guiding device comprising:

• a guide rail;
• a slider;
• and
• a plurality of balls, wherein
• the slider is provided at an outside of the guide rail;
• the guide rail and the slider face with each other and respectively include, at mutually facing positions, a raceway groove to form a raceway of the balls, and both of the raceway grooves extend in a longer direction of the guide rail;
• the slider includes a slider main body and a pair of end caps;
• the raceway groove and a return path of the balls are formed to the slider main body, and a direction changing passage of the balls is formed to the end cap;
• the balls are provided in a circulation pathway including the raceway, the return path, and the direction changing passage;
• an are groove configured to form an outer peripheral surface of the direction changing passage is formed in a side facing the slider main body of the end cap;
• a tongue unit configured to scoop up the balls from the raceway and guide the balls to the direction changing passage is formed to an end of a side of the raceway of the arc groove;
• a distal end surface of the tongue unit includes a plane perpendicular to a direction along the raceway and a circular-arc surface configured to cave into an arc shape from the plane;
• a curvature radius of the circular-arc surface is smaller than a radius of the balls;
• a center of a circle indicating a curvature of the circular-arc surface is present on a line shifted from a groove bottom line of the arc groove by at least an offset amount between the raceway groove of a side of the guide rail and the raceway groove of a side of the slider;
• and
• via the balls rolling within the raceway m a load state, the slider linearly moves along the guide rail.