Spline

A spline is a precision-engineered mechanical element featuring a series of parallel ridges (teeth) machined along the length of a shaft or bore. These teeth engage with corresponding grooves in a mating hub or sleeve to create a positive, non-slip connection for transmitting rotational torque. Unlike keyways, splines provide a multi-tooth contact surface, distributing the load more evenly, which allows for higher torque capacity, reduced stress concentration, and the ability to accommodate axial movement (sliding) between the connected parts. They are critical in applications requiring precise angular alignment and reliable power transfer under dynamic conditions.

Splines operate on the principle of positive mechanical engagement. The external teeth of the shaft interlock with the internal teeth of the mating component. This interlocking creates a form-fit connection that prevents relative rotation, thereby transmitting torque from the driving to the driven element. The multiple teeth in contact distribute the transmitted force across a larger surface area compared to a single key, reducing shear stress and wear. The design often allows for axial sliding motion along the engaged length, enabling functions like gear shifting in transmissions or adjustable positioning in couplings.