A hollow shaft has a hollow bore through the center of the shaft, and has the following characteristics.

Hollow shaft characteristics

	1.	The through bore can be utilized for various purposes.
	2.	Lighter in weight compared to solid shafts of the same diameter.
	3.	Notably, the through bore does not have high concentricity with the shaft, and cannot be used as an accurate guiding bore.

Each characteristic is explained in examples.

（1）Utilizing the through bore.

（a）Cooling of the shaft.

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In order to prevent the shaft temperature rise due to friction, fittings can be mounted on the ends to introduce various cooling medium (air, water, etc.) through the hollow bore.

（b）Guiding electrical wire and other plumbing components.

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Motor cables and air cylinder's air supply can be run through the bore in cases where way covers and other components are obstructing the routes. (See [Fig.1])

（2）Lighter in weight compared to solid shafts of the same diameter.

For applications where the shafts reciprocate, the weight of the shafts affect the sizing of actuator's prime mover. Cost reduction, energy savings, and motor heat reduction can be gained by keeping the prime mover as small as possible. However, the hollow shafts generate louder noises when subjected to bearing motion, as compared to other shafts in general.