Shaft Diameter and Loads

Shaft shear; http://www.pumpcalcs.com/calculators/view/80/

A shaft does not only transmit torques it also often supports radial and/or axial loads.

The diameter is determined taking ALL loads into consideration not only shear.

Cool your jets, old horse.

Nick Name gave the correct answer. All three loads are considered for any shaft design. Others (shock, thermal, etc) may be considered also.

Be careful about responding negatively to somebody who knows what they're talking about.

I'm sticking with shaft shear as the primary stress and telling you your nothing but Timken's cop and thats not flogging the horse dead!

Most axial and radial loads are borne on bearings and if exceeded then inspection and faulty operation causes the shaft to be replaced or repaired. The idea of engineering the calculation of axial and radial load is rarely reflecting on the shafts capabilities other than probability to withstand some flex which is choice of material question anyway! The radial and axial calculations are just good forms of guesswork unless you take all the operational calculations into account.

I will close my participation to this discussion with following comment:

I doubt that you have designed many shafts in your professional life and that you understand how it has to be done and why.

I am not glad to make such a comment but even the fact that you mention forces as affecting only the bearings conforts me in this estimation. The flexion of shafts have an important effect on bearings especially on roller bearings and journal where angles on the bearings lead to a peak of local loading and reduction of life expectancy either due to fatigue or to intensive wear since lubrication is sensitive to high presszures. Look at a Stribeck curve it will explain you why.

Bending moments on shafts depending on the local stress concentration factors are very often reasons of failure.

No reason to answer since I shall not any more look at the thread.