Hi,
We have a large ball mill. It has a 500 hp motor driving a Falk Gearbox that in turn drives a pinion shaft which drives the bull gear to turn the ball mill.

The alignment between the gearbox and pinion shaft is what I suspect to be a problem as the gears are straight cut spur gears. The Coupling between the shafts are Falk Gear types.

The Motor turns at 1785 rpm and the pinion shaft turns at 214 rpm. The Spectrum is showing a mound of energy at the pinion shaft tooth count at .184g's and a much larger harmonic showing up at 2x Pinion shaft gear tooth, .512g's in amplitude. The Gear Surface is a little rough but not terrible.

Any thoughts as to why the axial is so high as compared to the radial readings at the same point? By the way, the trend is fairly stable and has been for over 5 years. If it is a problem it doesn't seem to be too urgent.

Thanks
G

I would think the shaft is bent at the coupling.

Hi dataware,
I notice that your location is Goose Creek, SC. Where do you work. I too am in Goose Creek, I work at the Dorlastan plant in Bushy Park.

Alcoa
Gary

I suspect the second order of gearmesh indicates a misaligned pinion.

Hi all. If you have a segmented bull on the mill and you are taking a few averages, I would suspect it is misalignment between the pinion and the bull causing this. Maintenance personnel would routinely lead the mesh and realign, adjusting for wear. If they are allowing significant variation segment to segment on the bull (for example, checking only part of the total bull gear mesh with the pinion), you'll see misalignment no matter how well their "final" might be. This would explain some constancy in readings. Of course, if you've not had that drive apart, failed any of the drive train, or had the mill off the stand in five years, you need to call that spectrum "excellent" Just my 2cents.