Splines are ridges or teeth[1][2][3] on a drive shaft that mesh with grooves in a mating piece and transfer torque to this, maintaining the angular correspondence between them.

For instance, a equipment mounted on a shaft might use a male spline on the shaft that matches the gear rack female spline on the apparatus. The splines on the pictured drive shaft match with the feminine splines in the heart of the clutch plate, as the smooth suggestion of the axle is definitely supported in the pilot bearing in the flywheel. An alternative solution to splines is a keyway and crucial, though splines provide a longer fatigue life.[2]