Construction and Features    Three longitudinal ridges are provided equally spaced at 1200 intervals on the spline shaft. Two rows of balls are in close contact with both sides of each ridge, for six rows of balls in total.
The grooves of the raceways are precision machined to a profile the diameter of which is nearly the same as that of the ball. When the spline shaft or spline nut is subject to torque, the three rows of balls in the direction of the torque uniformity carry the load so that the rotational center is automatically established. When the torque is reversed, the opposite three rows of balls will carry the load.
The balls are maintained by a retainer in such a manner that they neatly circulate along the raceways. The balls will not fall out even if the spline shaft is removed.