Hollow shaft vs Solid shaft – Difference (Explained)

The key point that differentiates the Hollow shaft vs Solid shaft is that the cross-sectional area of the hollow shaft is spread away from the axis of rotation while the cross-sectional area of the solid shaft is spread closer from the axis of rotation.

Solid and Hollow shaft:

As shown in below figure-A, the solid shaft doesn’t have any hole at the center while the hollow shaft has a through-hole at the center of the shaft cross-section.

The profiles of the circular solid shaft and hollow shafts are shown below.

As shown in the above figure, for the hollow shaft, the cross-sectional area is spread away from the axis of rotation. For the same weight per unit length, the hollow shaft has a high moment of inertia than the solid shaft. Therefore the hollow shafts are stiffer than the solid shafts for the torsional and bending load.

Thus for the same weight, the hollow shafts have higher torsional stiffness and bending stiffness than the solid shafts.

Hollow shaft vs Solid shaft:

Sr. No.	Hollow Shaft	Solid Shaft
1	The hollow shaft has a hole at the center throughout its length.	The solid shaft doesn’t have a hole at the center.
2	For the same outer dimensions, a hollow shaft has less weight than a solid shaft.	For the same outer dimensions, a solid shaft has a higher weight than a hollow shaft.
3	For the same weight per unit length, the hollow shaft has a high moment of inertia than the solid shaft.	For the same weight per unit length, the solid shaft has less moment of inertia than the hollow shaft.
4	The hollow shaft with the same weight per unit length bears maximum torque than the solid shaft.	The solid shaft with the same weight per unit length withstands less torque than the hollow shaft.
5	For the same weight per unit length, the hollow shaft bears more bending load than the solid shaft.	For the same weight per unit length, the solid shaft bears less bending load than the hollow shaft.
6	Hollow shafts with the same weight per unit length are stiffer than the solid shaft.	Solid shafts with the same weight per unit length have less stiffness than the hollow shaft.
7	The natural frequency for the hollow shaft is higher than the solid shaft.	The solid shafts have less natural frequency than the hollow shafts.
8	The cost of the hollow shaft is comparatively higher.	The solid shafts are less costlier than the hollow shaft.
9	The cross-section area of the hollow shaft is spread away from the axis of rotation.	The cross-section area of the solid shaft is spread closer to the axis of rotation.
10	The radius of gyration is away from the center.	The radius of gyration is closer to the center.

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