Abstract: A spline joint includes an externally splined shaft end and an internally splined hub end engaged therewith. The shaft end has an annular groove around the spline portion wherein a plurality of locking balls may ride. The hub has the same number of holes as there are locking balls, each of which hole is adapted to receive a locking ball. A sliding sheath surrounds the hub. This sliding sheath has an annular projection and an annular groove in axially spaced relation around its internal face. The annular projection presses against the locking balls when the spline joint is in operation. The annular groove embraces a polygonal spring, the spring having the same number of sides as the number of locking balls. The center of each side of the polygonal spring presses against a lock ball from a radially outward position and prevents the lock balls from going out of position when the spline joint is being detached.