RCM-2009 Reliability Centered Maintenance Managers' Forum - March 23-26 - Daytona Hilton Ocean Walk Village - Daytona Beach Florida Join or Manage Your Profile Posting Boards Machinery Condition Monitoring and Predictive Maintenance Posts About vibration/alignment/balance Vertical Motor/Agitator issues
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Good afternoon all. I need help on a vertical mount motor/Gear reducer set. Motor is AC 1780 rpm. Output speed for the Gear reducer is 93 rpm. There are 6 units exactly the same and this one is showing substantially higher readings. I have attached some data for you to view. Should I be thinking along the lines of a resonance issue?? I have bearing info and no luck there. I have not received all the gearbox info, should have soon!! ANY comments would be helpful.
Thank you so much for all the help!! 1760.doc (88 Kb, 30 downloads) |
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A wild guess, 6 blades rotating at 100 rpm for the agitator maybe the 3 peaks are harmonics.
Maybe a damaged blade? Steven van Els, CMRP |
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vib01,
We have a few of these vertical agitators. One style uses a "vertical" motor (c-face, sits in a machined boss) the other uses a normal horizontal motor (sitting on a scoop mount that is turned vertically). With the second style we have to be careful during motor installation/alignment...it's easy to let the motor slip down & the coupling will take the full weight of the motor and ruin any coupling gaps that we were supposed to have. The vibration data looks KINDA similar to yours...hows coupling life? Any coupling debris in the area? |
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Hi Keith,
Actually the set up is similar to what you said " c-face, sits in a machined boss. This is exactly what it is. There is a coupling in there as well and I am told that they have "never" had problems with that. Can this style of motor with c-face have problems and that is why the high axial? |
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vib01,
Hmmm, we've only had trouble with the other style. Has anyone worked on this machine recently? Just thinking out loud...suppose the motor was replaced and the motor side coupling hub was not positioned correctly...Come to think of it, what type of coupling is this? Splined, flex? If this is a small agitator (10 or so HP) we have seen high motor/input 1x and found looseness at the reducer/tank top connection. It never made sense to me (I expected output speed harmonics) but it might be worth a look. Good luck & let us know what you find. |
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I've had problems with the C-face fit! Rigid coupling? Remember your tolerance for alignment is; 80% of the diametrical clearance of the bearing. Set it up as perfect as you can and use taper dowels for indexing and repeatability else it'll be different every time.
Cordially, Sam Pickens pdmsampickens@gmail.com |
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Wow! Great feedback! Thanks!
Keith, As for the recent work done to this unit, yes in June the motor was replaced. Unfortunately, we do not have data that goes back that far, so I cannot tell you what the data looked like before and after the motor was replaced. As for the motor coupling hub, they tell me that the coupling cannot be aligned, that there is only one way to put the coupling in due to the machining of the c-face!? Does this sound correct?? I am pretty sure it is a rigid coupling. More to come on that as well. |
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The coupling is a BIPEX BWN 202, rigid. |
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If I am reading your spectrums correctly, it seems the motor inboard has a higher amplitude than does the actual gearbox point. Also the outboard end of the motor is lower in amplitude than the inboard end. Is this saying the whole system is not moving together at the same frequency. Have you checked the phase between the points?
How big is this system? Like the distance between the gearbox and the motor and the distance from the motor inboard to the motor outboard? Which spectrum is the gearbox horizontal to compare to the motor inboard horizontal? Is it possible that the 1312.5 peak is the speed of an intermediate gear in the gearbox or a resonance excited by one of the other peaks around it? |
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Yes it is possoble, I am still getting gearbox info trickling in. |
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RCM-2009 Reliability Centered Maintenance Managers' Forum - March 23-26 - Daytona Hilton Ocean Walk Village - Daytona Beach Florida Join or Manage Your Profile Posting Boards Machinery Condition Monitoring and Predictive Maintenance Posts About vibration/alignment/balance Vertical Motor/Agitator issues
Join or Manage Your Profile Posting Boards Machinery Condition Monitoring and Predictive Maintenance Posts About vibration/alignment/balance Vertical Motor/Agitator issues
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