Vibration in the open gear drive system

Gear Misalignment almost always excites second order or higher GMF harmonics which are sidebanded at running speed.

The FFT spectrum will often only show a small amplitude 1x GMF, but much higher levels at 2x or 3x GMF. Important to set the Fmax high enough to capture at least 2 GMF (standard practive is for FMax of 3.5 x GMF) harmonics if the transducer has the capability.

Observe the sounds around the unit, if you can hear a modulation e. g. (simply put)the sound varies at a set and repeatable rate you will likely be able to observe this modulation in the timewave form which will relate to sidebands in your FFT spectrum.

If you have access to the appropriate equipment I suggest you perform phase analysis which will be of great help as it is a very powerful diagnostic tool.

I suggest you check for the presence of sidebands, this will point you in the direction of the problem gear as the sideband spacing will be at the rotating speed of the "offending" gear.

This might not solve you problem but give you something to work with, good luck.

I think you are right we have 2 harmonics in 1XGMF was having lower amplitude than taht of 2 X GMF and we had side bands which were very low values
is that a misalignment then can we find out through other means - I think I can do that with Temperature Meter

Check your gear wear pattern. It will be most prominent at the pinyon gear. More wear on one side = horizontal misalignment. Both sides near the edges = vertical.

Look for modulation at pinyon shaft speed and mill speed to indicate gear runnout. Gear runnout on the mill is very common.

quote:

Originally posted by Arupanjan:
I have a question
in an open gearing drive system in ball mills the pinion free end vibration two dominant peaks are observed in 1 and 2 X GMF and 2GMF the amplitude is higher and is around 13 mm/ sec
can we determine the problem from this in theis drive system
the values are RMS values
any one for help

I think that you are having a misalignment problem in that gear. one year ago I had a problem in a gear of mill (cement) and the 2GMF was higher than first GMF. The diagnosis was misalignment. If one of the shaft gear is the same as the distance between the sidebands around the GMF, that will be the offended gear (victim).