the following example is for you reference.
the spline shaft is a kind of mechanical transmission. the flat key, the semicircular key, and the oblique key have the same effect. They all transmit mechanical torque. There are longitudinal keyways on the surface of the shaft. The rotating parts on the shaft also have corresponding keyways, which can be maintained. Rotate synchronously with the axis. while rotating, some can also slide longitudinally on the shaft, such as gearbox shift gears, etc.

  

 

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