Power transmission vibration damping
Power transmission vibration damping
(OP)
Long story short, we have a transmission system that has a vibration. Decision was made that we need to get it back in service for now until there is time to do a proper rebuild and find the cause. This trans box is Al with high low ranging and a single 3ph motor standing vertical on it.
We need to isolate and damp the vibrations from carrying into the rest of the machine. Frequency was tests to swing from 40-110hz in our operating range. We did not have good calibration to give an amplitude this is a vibration you can hear and feel but certainly nothing sends you running for the E stop.
I was playing with some steel plate and seemed to be able to get about 30-40% out by contacting the motor up top. I do not have specific experience with damping and not sure if we might try a hand in a fluid device as sort of an active damper or if mass is king here? We are a bit limited on space but can fit some Lead in there but don't have any on hand any the moment.
We need to isolate and damp the vibrations from carrying into the rest of the machine. Frequency was tests to swing from 40-110hz in our operating range. We did not have good calibration to give an amplitude this is a vibration you can hear and feel but certainly nothing sends you running for the E stop.
I was playing with some steel plate and seemed to be able to get about 30-40% out by contacting the motor up top. I do not have specific experience with damping and not sure if we might try a hand in a fluid device as sort of an active damper or if mass is king here? We are a bit limited on space but can fit some Lead in there but don't have any on hand any the moment.





RE: Power transmission vibration damping
If you go the latter route then some sort of flex coupling or hydraulic coupling provides the best shot at first time success, although I agree a big lump of lead in the right place can work wonders.
If you want some idea of a measurement based approach then you might have more luck on http://www.eng-tips.com/threadminder.cfm?pid=384
Cheers
Greg Locock
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RE: Power transmission vibration damping
Even 100 Hz is pretty low. Sounds like this -
http://www.youtube.com/watch?v=mejO0hV_w80
RE: Power transmission vibration damping
You might also stiffen the overall structure to raise the resonant frequency, which may solve the problem if you don't have any excitation frequencies in that range.
However, 40 - 110 hz means that you've got a heavy mass on a relatively compliant spring. Have you tried rubber isolators for how it's mounted? Or some other type of vibration-absoring material?
Engineering is not the science behind building. It is the science behind not building.
RE: Power transmission vibration damping
I have already used some rubber isolators and YES, they do help quite a bit but I am wondering about combining mass damping with the rubber isolators to get the most effect. Because the motor is standing up on a pedestal so to speak, unsupported other than the C face mount bolts, it is allowed to vibrate.
RE: Power transmission vibration damping
RE: Power transmission vibration damping
Have you verified that it's a motor/transmission problem by removing the drive belt and running the motor speed up and down?