shock test failed

[boydli]

Hello all,

A ploblem is here that we need the parts strong at some level but can not too strong as bad effect.
the failure appears when a sudden stop applied on drive shaft, then this shock torque from shaft will be transfered to a planetary reduction gear,then the gear will be broken.
Between the drive shaft and reduction gear, there is a overrun clutch for transfer the torque .
it's also for protection if too high speed of shaft, then this clutch start to work and no high speed transfered to reduction gear.

I doubt the material or heat treat used on these parts have some problem, when at sudden shock, there is not enough buffer or deformation on the parts to absorb the shock energy.
I don't like to change the failed gear to a more strong material, but want to know how to make some change on parts,such as drive shaft or overrun clutch, to get enough buffer for the shock energy, and no plastic deformation on them.
I'm not professional on steel material, but i doubt there should be a balance between the hard strength and elastic strength.
maybe change the material selection , maybe change the heat treat method.
any one can give some advice about it ?
Thanks a lot.

 

[monkeydog]

Are you using "poweder-met" for the gears?
They are not very forgiving to shock loads.

 

[tbuelna]

boydli,

What is the magnitude of the overload condition your gearset is subject to?

Basically, you have three options. You can make your gears stronger, you can add some sort of component to your system (like a quill shaft) to increase its torsional elasticity, or you can add some sort of torque limiting device to the system.

 

[drawoh]

boydli,

A shock load is energetic. To deal with one, your structure must convert the kinetic energy of your load into strain energy. If you can place a spring element between your gear and your load, that will do it.

If you do not understand strain energy, you need to talk to a mechanical engineer.

--
JHG