Splineless Coupling

a connection between a shaft and a joined part that does not use splines which would preclude their relative rotation and sometimes their axial displacement. It is achieved by friction (connections with guaranteed tightness and with spring clamping rings) and by meshing (serrated, square-cross-section, and shaped-profile connections). In a narrow sense shaped-profile connections over cylindrical or conical noncircular surfaces having a smooth section are called splineless couplings. The drawbacks of a splineless coupling are the strains in low-stiffness parts and the increased friction, which makes it difficult to shift a part axially along the shaft under load; an advantage is that a surface with a smooth section can be machined by the profiling method.