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Strange gear tooth pattern

Strange gear tooth pattern

Strange gear tooth pattern

Hello Guys,
in attachments you found some photo about strange gearbox tooth pattern found. Before the inspection i made some vibration measurement on it discovered this:4

-1XM in axial 13,5 mm/s
-2XM in radial 16 mm/s
-1XGMF 2mm/s

THis machine is forming roll in a papaer machine (MOTOR-PENDULUM GEAR-CILYNDER) normally working one side of teeth.
All of your consideration about tooth pattern will be helpfull.


RE: Strange gear tooth pattern

It looks like not enough or improper lubrication, possibly exaggerated by too little center distance forcing the teeth into mesh. It's what I expect if there was crowning on the gear teeth causing the wear to fall off at the ends of the teeth.

Instead of being forced into mesh, an alternate is contamination is filling the normal gaps and causing displacement that looks much like it. Checking the oil for powdered metal fragments would tell that.

On the other hand, they look well aligned; have they been running for a long time? It's possible that they were run without enough lubrication some time in the past even if there is enough now.

RE: Strange gear tooth pattern

the other possibility the gear lead is off . to much helix angle thus causing contact at ends.
ask for the gear charts when manufacture. other could be cased by misalignment in the gear box.

RE: Strange gear tooth pattern

See my response in your other posting.


RE: Strange gear tooth pattern

The most serious issue appears to be a combination of pitting and scoring on the gear flanks. The pinion flanks look to be in much better condition. Could be a problem with the gear material/heat treat. Significant pitting/scoring damage on both the coast and drive flanks of the gear teeth might also be due to mesh interference from insufficient backlash or pitch center location errors. The small diameter pinion and large diameter gear combination used typically requires a fair amount of geometry tweaking (profile shift, addendum adjustment, tip relief, etc) to ensure smooth meshing.

The contact pattern at the end of the gear flanks above and below the pitch diameter in picture 4 shows a hollow profile condition. A manufacturing issue with the gear teeth.

RE: Strange gear tooth pattern

Thank you to all guys

Really the gear resonance could create these effect? It is a real case you follow up by yourself?

RE: Strange gear tooth pattern

Seems to me that it's more likely that design/functionality errors lead to resonances, rather than the other way around. It would have been noticeable from the initial installation, if there were resonances.

TTFN (ta ta for now)
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