Gear Mesh Approach Action

[SKinzel]

I know that AGMA recommends approach action in a gear mesh to be below 50% and I understand why. What I haven't figured out or found any reference for is what would be the lower limit of approach action percentage? I've seen and even designed sets as low as 33% approach action and as far as I know there haven't been any problems with the gears.

Any thoughts?

 

[tbuelna]

Skinzel,

Approach action in a gear mesh is a less efficient contact condition than conjugate or recess action. Thus approach action will tend to produce more friction and heating within the lubricant film.

If your gear mesh might have a problem with scoring, then reducing/eliminating your mesh approach action condition through geometry mods would be of great benefit. The acceptable amount of relative contact sliding (whether approach or recess) will be determined by your mesh's scoring function, and the lubricant's flash temperature limit.

Good luck.
Terry

 

[SKinzel]

Thanks for the reply. I understand those things but what I'm curious about is there a lower limit to percentage of approach action? I ass/u/me that decreasing the approach action is a case of diminishing returns. Maybe this is not correct?

 

[carburized]

Skinzel

We sometimes designed gears for as low as 25% approach action with no problem at all.