shock test failed as may material too strong

[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 materials used in these parts looks too strong, 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 selection.
any one can give some advice about it ?
Thanks a lot.

 

[Goahead]

You could install an overload safety device or a mechanical torque limiter, provided you can calculate the maximum admissible torque.

http://www.welding-advisers.com/

 

[tbuelna]

Maybe it's a language problem, but for the condition you described it would not be detrimental for the gear materials to be "too strong". What I'll assume you intended to say is that your drivetrain system's torsional stiffness is too high to prevent impulse overloads from producing a tooth bending failure in the driven gear set.

You can address the problem by making the driven gear set stronger, increasing the torsional compliance of the components ahead of the planetary input, or by adding a torque limiting device before/after the planetary gear set.

Hope that helps.
Terry