a joint made by projections (teeth on a shaft) and corresponding depressions (splines) in the opening of a part. Depending on the shape of the teeth, a distinction is made among straight-sided (the most widespread), involute, and small triangular joints.
In straight-sided spline joints, untempered parts are centered on a shaft along the external diameter, tempered parts with a polished centering surface of the opening are centered along the internal diameter, and in the case of low demands on precision in centering and for considerable loads, they are centered along the sides of the teeth. In involute spline joints, the stationary joining of parts is centered along the sides or along the external diameter, whereas with triangular joints they are centered only along the sides. Depending on operating conditions, spline joints may be movable (sliding) or stationary, with push fit and fixing of the part to prevent axial displacement.