Spine Shaft is named after its appearance.

    On the external surfaces there are longitudinally keyways. And the opposite keyways are on the spinner which is sleeved on the shaft, the spinner would have synchronous rotation with the shaft. 

    As rotating the shaft, there are some spinners could be longitudinal sliding motion, for example the transmission shifting gears.

    Another type of spinner, which is widely used in brake structure and steering, has to keep dead-lock.