Gearbox has high vibration since installation
2 weeks ago.

since installation - 18g's 3000hz waveform pk-pk value, mainly due to cluster of peaks near 80 orders of input speed.

Other gearboxes ( same model and ratio )have ran in this position for years with normal amplitudes of 4g's.

Gearbox has 44tooth pinion gear, 133 tooth output gear. The box does have a tag that states "RENEW" above the orginal tag that gives manufacturer model, mo# and ratio info.

Questioning if this is a so called "ghost frequency" in this box. Peaks at 44 orders which is gearmesh frequency shows low amplitudes, while the 80 order cluster of peaks are forcing the vibration up to 18g's.

Ringing noise is heard with headphones, the amplitude is lower at centerline in vertical direction and increases as I move tranducer higher up on the casing.

The installation manual for this gearbox shows possible oil wipers that are to have .010 clearance on this sides of the gear. Plan to inpect gearbox on next down day.

This model and ratio gearbox has ran in this position since this paper machine was built. Gearbox drives a Forming Roll on a tissue machine. There are no peaks at this frequency in the roll or motor, only in the gearbox and it is not occuring at gearmesh frequency.

any thoughts ?

Thanks
Mike

Mike
The ringing could be a resonance of one of the gears. We also had problems with renewed gearboxes.
Regards
Don

Mike,

It was long ago and I don't have any recorde, but I found a resonance in a fairly big single reduction Falk parallel shaft drive like you have. There are two parallel vertical plates with a hole cross-drilled for lifting. I found those plates to be in resonance and fixed it by welding a flat bar across them.

Donla and Danny

Thanks for your responses. Were down on the 3rd and removing the inspection plate and uncoupling to check backlash and axial float on the input and output shaft.

I was able to look inside the old box and the ouput gear has a oil pan around it.

The cluster of peaks that is causing the ringing does have output gear sidebands surrounding it but is not the gearmesh frequency or multiple of it.

The amplitude is high on on both the input and output on the west side of the box, while the east side of the box has considerably lower amplitudes on both the input and output shaft bearing covers.

Thanks again for your responses.

Mike