Spline Spindle is a mechanical transmission, peace key, semicircular key, oblique key function is the same, is the transfer of mechanical torque, in the appearance of the shaft has a longitudinal keyway, set on the shaft of the rotating part also has the corresponding keyway, can keep synchronous rotation with the shaft.At the same time of rotation, some can also be longitudinal sliding on the shaft, such as gearbox shift gear, etc.