Medium Torque Type Ball Spline

With the medium-torque ball spline, the spline shaft has two to three crests on the circumference, and along both sides of each crest, two rows of balls (four to six rows in total) are arranged to hold the crest so that a reasonable preload is applied.
The rows of balls are held in a special resin cage incorporated inside so that they stay aligned and recirculate. With this design, balls will not fall even if the nut is removed from the spline shaft.