BALL BEARING FOR LINEAR MOTION

PURPOSE: To operate a linear motion ball with almost no noise, to firmly construct it and to economically manufacture it by forming the bearing with covers which are fixed at both ends of a cage having axially extending raceway tracks for loaded balls and axially extending return raceway tracks for unloaded balls and have turnaround raceway tracks connecting the extending raceway tracks to the return raceway tracks, balls guided by the raceway tracks on an endless line, and slots extending along the raceway tracks and opened to a shaft. CONSTITUTION: The turnaround raceway tracks 15 of covers 7 on both sides have slots 19 opened to a shaft 14 and communicated with the slots 18 of extending raceway tracks 8 and the slots 20 of return raceway tracks 10, and the slots 19 are bounded by curved shoulder sections 16 on the inner surface of a cage 3 and extending along turnaround raceway tracks 15 and the curved inner wall sections 17 of the covers 7 extending in parallel with the curved shoulder wall sections of the cage 3.