MAAG Gear LGD-32 High Vibration

We have a problem in our gearbox related to vibration on high speed shaft both ends horz and vertical and on base bolts. Vibration transmitting to 2nd shaft ( Intermediate shaft ) also. 

    Observed Abnormal Vibrations on Gearbox Input and Intermediate shafts, particularly on horizontal 5.5 mm/s and 7.0 mm/s and vertical 6.4 mm/s and 5.8 mm/s respectively recorded today.  Also High G’s Values on Input and Intermediate shafts 2.6 g’s and 2.9 g’s respectively along with significant impacting & abnormal High Noise.In a Spectrums found Gear mesh Frequencies of Shaft 1 to shaft 2 occurring on 38th order with relative peaks and harmonics. Also some bearings faulty peaks affected by gear meshing vibration energy.  In a waveform high level of significant impacting and amplitudes modulations present once per revolution.However amplitudes of sidebands with GMF are still low and constant and some times fluctuates.

Found High Vibration on Super bolt 1 particularly on vertical direction between 7 mm/s to 9 mm/s continuously and 1.9 mm/s on horizontal. Also on other all three bolts vibration on vertical direction  is higher than horizontal. Collected Phase data between Super bolt base  and concrete base in vertical direction,  giving 165 degree phase difference,. So what I should suggest to Management for maintenance? Need you Opinion.

I have attached the readings and  spectrums waveforms.

Thanks 

 

Attachments

Original Post
John from PA posted:

Is this the same gearbox you asked about almost a year ago?  See https://www.maintenance.org/top...-vibration-and-sound.   

Even if the same or different gearbox I would have the same questions today as I did back then.  See my reply at in the reference thread at 2/5/1710:04 AM.

 

What exactly is this "super bolt" you make reference to?

I noticed that this machine has a relatively complex foundation (again, view the video) I believe designed to provide load sharing at the girth gear by providing mount flexibility.  Have you checked all the various fasteners for proper tightness in the foundation.  Lastly, what exactly makes you think the vibration is high?  Does the OEM (Maag) provide specific recommendations.

 

I daily check the vibration on all four superbolts and base, i find high vibration on bolt 1 as compare to other threes. there is also high vibration on concrete base upto 20 mm/sec on vertical direction near to superbolt. vibration is directional mostly on vertical on all shafts points. I think Damping within the system deteriorated causing a shift in the natural frequency to coincide with the fault frequency so vibration amplifies,the system stiffness might have changed. all the superbolts are properly tightened a week before, all grouting bolts are also tightened.
Can you think i need to check phase analysis there? or what other suggestions to achieve other any valuable analysis?

Hmmm, I'm used to calling them multijack bolts.

It does sound as if some foundation deterioration has been going on.  You mentioned tightening these bolts a week earlier; "all the superbolts are properly tightened a week before, all grouting bolts are also tightened."  Do you know if bolt #1 required any unusual tightening as compared to the other bolts?  

 

Rizwan Sulehri posted:

I think I m just wasting my time here, people dont know what is superbolt

Unfortunate you feel that way.  I didn't know what a superbolt was, and specifically asked that question, and you failed to answer.  Walt Strong pointed me to an answer.  I happen to call these devices a multijack bolt, somewhat more generic as opposed to a trade name.  

You have not been forthcoming in your answers.  When I asked "Do you know tooth numbers for every stage?" you replied "I know the teeths of all gears" but didn't give the actual numbers until I made a 2nd request.  When I asked "Lastly, what exactly makes you think the vibration is high?  Does the OEM (Maag) provide specific recommendations" you didn't reply.  Your old thread, the link I provided, same situation.  When Becar pointed out you had attached the wrong document, I stated we needed tooth counts, bearing numbers, etc. and nothing was provided.  I think you provided a "new" document (not of much use for the problem) as an edit to your original post, but you never again replied to that thread.

I just today read your post. I have a question or two, if you do not mind. 

Other than the 165 degrees phase difference in the base plate and the concrete, did you see any actual movement between the base plate and the concrete?         

Was there any phase difference in the #1 "Supperbolt" and the plate vertically? I think you said the #1 Bolt had 7 mm/second movement vertically.

I am wondering how the bolt would move in the vertical direction without everything moving? Did we check the plate movement next to where you got the 7 mm/sec on the bolt? Is #1 bolt pulling out of the concrete?

Thanks and Have a Great Day.

Ralph

 

 

Rizwan I dont know why but i am unable to open the files you have attached still I have seen a case where the mill was having 2 drives the lifting & the pressing when any of the motor of mill 1 was taken out for maintenance the vibration level in a similar mill close to it sharing same foundation was highly affected & went high so there could be the possibility but Cement mill center drive using a MAAG gearbox must be close to max 10 years old & that is not a long period for foundation deterioration for a cement mill anyways before opening you can do UT for the holding down bolts to see any damage in the superbolts or other holding down bolts

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