# Simple torsional stress question

1. Aug 30, 2015

### kubedgamer

I am having trouble understanding a relatively simple concept.

A motor is connected to an impeller directly. i.e Motor -> shaft -> impellers

A motor is also connected at 90* to an impeller/shaft i.e Motor -> small shaft -> bevel gears (as linked below) -> shaft -> impellers

http://www.bandhgears.co.uk/images/bevel_gear_suppliers.gif

Will the torsional stress induced by a load on the impellers be better absorbed in the second instance by the gears thus putting less stress on the motor?

2. Aug 30, 2015

### OldEngr63

The gears will add a small amount of inertia to the system, but otherwise, the two are identical. There is no useful stress reduction achieved by the gears.

3. Aug 30, 2015

### kubedgamer

Thank you. Is there some sort of literature I can read about a proof for this?

4. Aug 30, 2015

### OldEngr63

Why not do your own analysis of the system? Write the equations of motion, draw the stress blocks on the shaft(s) and find the stresses for yourself. That will be the most convincing approach.