Vibration problem

[nanuuk]

I have a Mycom 6B recip compressor that has a viration to it it. Opened up the compressor and did a top end overhaul with no unusuall signs. Opened the crank and checked the sump and found no signs of metal, bearing caps where fine a little wear but again nothing out of the ordinary which takes away the the thought there is a problem with the main or thrust bearing? Belts are good and and its a new motor all the mounting bolts to the compressor and the motor are tight any suggestions on what else we can check?

[chillerman2006]

I have a Mycom 6B recip compressor that has a viration to it it. Opened up the compressor and did a top end overhaul with no unusuall signs. Opened the crank and checked the sump and found no signs of metal, bearing caps where fine a little wear but again nothing out of the ordinary which takes away the the thought there is a problem with the main or thrust bearing? Belts are good and and its a new motor all the mounting bolts to the compressor and the motor are tight any suggestions on what else we can check?

HI nanuuk

could be due bottem end overhaul (visual can be deceptive), not sure of intervals or oil problems can cause noise/vibration

Your obviously not a novice so dont mean to sound like teaching you to suck eggs.

Does the motor run ok without the belts - could be a dud from new

R's chillerman

[benijoseph]

Mr, nk

vibration is cyclic or continuous ?

rgds.

[nanuuk]

cylclic as in 2 seconds there then smooth for 2 seconds and so on.

[benijoseph]

Mr, NK

most probably your oil pump is not supplying proper oil to shaft it might defective, (if it is oil pump type)OR pipe connecting oil pump might have short length or small peace might have broken,OR oil level might not be proper check floor alignment or check entry of liquid into your suction side.

rgds

[RANGER1]

nanuuk,
Could be a number of things as sometimes when machine is unloaded with belt drive the belts can get a flap up. Not much you can do except keep belts to correct tension.

Has it started vibration suddenly or since any particular work was carried out?

Some "V" belts are like rubber bands & are not suitable like cog type belts.

If motor is out of balance problem can also occur, maybe run motor without belt on & see if any vibration.

Compressor base should also be firmly secured to plinth, with no part of base not touching.
This can act like a trampoline with harmonics.

Check that flywheel is tight on shaft.

[chillerman2006]

Mr, NK

pump proper shaft pump pipe pump have short length or small peace

I'm with you on this beni, but I would not be letting everyone know what one has down below :rolleyes:

[chemi-cool]

I would have a check on the valves, any crack or a broken piece changes the balance of the compressor.

I dont work though with such big compressors but up to 80HP demaged valves have that influance.

[RANGER1]

I have a Mycom 6B recip compressor that has a viration to it it. Opened up the compressor and did a top end overhaul with no unusuall signs. Opened the crank and checked the sump and found no signs of metal, bearing caps where fine a little wear but again nothing out of the ordinary which takes away the the thought there is a problem with the main or thrust bearing? Belts are good and and its a new motor all the mounting bolts to the compressor and the motor are tight any suggestions on what else we can check?

We had a new Teco motor out of balance cause something very similar to this, which also caused belt flapping.

You have tried to eliminate compressor as best you can without full overhaul.

If main & thrust bearing is worn excessively, I would have though shaft seal would have some problems.

What about motor pulley, is it new as well,is it running true?

[Yvan]

I have a Mycom 6B recip compressor that has a viration to it it. Opened up the compressor and did a top end overhaul with no unusuall signs. Opened the crank and checked the sump and found no signs of metal, bearing caps where fine a little wear but again nothing out of the ordinary which takes away the the thought there is a problem with the main or thrust bearing? Belts are good and and its a new motor all the mounting bolts to the compressor and the motor are tight any suggestions on what else we can check?

This is a minimal amount of info with which to complete proper vibration diagnostics. But based on the above info, the internals have been checked so hypothetically internal issues could be ruled out. I believe that you mentioned cyclic vibration, high for 2 secs, then gone for 2 secs. First thing that comes to mind is that the vibration is coming in and out of phase possibly with another machine in the same room. Someone mentioned motor imbalance, again based on the info, I would rule this out. Motor vibration will cause a high 1X amplitude at motor running speed, but it should be a consistent vibration.

[Magoo]

I would suspect the v/belt setup and sizing, tension etc., as Ranger said have you checked the flywheel on compressor. Could be the pulley on the new motor, is it running true and the taper loc pulled up square.

[mbc]

how was sump in your compressor ? is it too much? how was sump on head of pistons and cylinder ?
I agree with ranger1 might be from those items, but if one of your valves plate was broken or does not fit or one of unloading does not works might we get vibration in compressor ,
also check all mounting bolts might they loose

[Yvan]

If there is a vibration issue, then you need a vibration analyzer to study the spectra and/or waveform in order to take corrective actions. Checking this and checking that can be time consuming and not yield proper results, I see it simply as "grasping at straws". The OP mentions "cyclic" vibration which is but one clue which in itself rules out certain issues.