Gear Quality Rating

[henschen]

Am working on a planetary gear train, and I am getting gears in at a lower gear quality rating (Q5 rather than Q7) than I specified. What is the impact of the lower quality gears...durability, noise...? I need to know what my risk is to use these gears. What characteristic am I most likely to see a problem with and how can I test?

 

[Philrock]

They will be noisier, and will have somewhat lower power ratings due to larger dynamic loads (due to larger pitch variation). Modern gear rating software considers AGMA or ISO quality level.

 

[pdybeck]

The old AGMA gear rating system has been changed to adopt the ISO format (I think). You might want to get your hands on a copy of the newest AGMA standard and also ask what was supplied. The new AGMA rating system is the opposite from the way it used to be (and probably how it is mostly still used). Its opposite in that a lower number is a higher quality, rather than the other way around. You might want to specify on your drawing/spec what version of the AGMA standard your Q7 number applies to.

Pete

 

[israelkk]

The AGMA "C" Tolerance source identifier Indicates the tolerances in ANSI/AGMA 2015-2-A06. The letter Q was used to designate tolerances from AGMA 2000-A88 and 390.03. If no letter is shown, tolerances in AGMA 390.01 or 390.02 apply.

 

[plasgears]

If you can tolerate plastic gears, a lower Q level is acceptable because of greater flexibility and inherent sound absorption. Some designers are specifying plastic and PM gears exclusively.

PM gears can benefit from oil quench after sintering. The oil can make the difference between failure and acceptable life.