Planet set gear addendum modifications and clearance.

[ukjay1]

Hi Guys

I have an planetary set I'm designing, where I had to do addendum modification to sun gear none to planet gear, and this increases the center line distance.

Now is the general rule of thumb to make the same negative addendum modification to ring gear? To have proper clearance? Or do I move the ring gear cut pitch dia out further (i.e..amount of center distance change)?

As it looks to me the 1st option in laying it out I'm getting intereferance with planet and ring gear.

Please comment with suggestions.

Thanks

 

[tbuelna]

ukjay1,

With simple epicyclics, there are lots of tweaks and compromises to balance the requirements of tooth bending strength, relative contact sliding, etc. You can adjust the ring gear PD, the planet gear PD, the planet gear PCD, or any combination thereof. Just remember to fully evaluate the effects of these tweaks with regards to issues like contact sliding. Also be sure to apply adequate tip relief to your gear teeth to ensure smooth meshing.

Hope that helps.
Terry

 

[dinjin]

Your method works and probably is a good method rather than changing the center distance depending on how much you modified your sun gear. You might want to consider stubbing the ring gear a bit too.