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Additive frequencies

Additive frequencies

Additive frequencies

(OP)
Is it possible to have a gearbox with a 30Hz input and 35Hz output shaft speed cause a 65Hz vibration frequency response? We have a machine with repeat bearing failures which has a dominant frequency of vibration at 65Hz which lines up to nothing else except the addition of the input and output shaft speeds??

RE: Additive frequencies

what about the bearing failure freqs?

peace
Fe

RE: Additive frequencies

"Is it possible to have a gearbox with a 30Hz input and 35Hz output shaft speed cause a 65Hz vibration frequency response?" Not in a linear system. However gearboxes are full of non linearities. Gut feel is that second order of one or other shaft is a more likely contender.

Can you post a spectrum?
 

Cheers

Greg Locock


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RE: Additive frequencies

Let's say the 30hz bull gear is eccentric. It puts 30-hz varying stress on 35-hz rotating pinion.  That could create a 30hz varying bow on the 35-hz rotating shaft which might modulate 35hz unbalance or modulate 35hz misalignment forces resulting in 35 +/- 30.

Just a thought. One of many ways for modulation to occur.

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