# Bearing failure help



## Jabberwoky (Sep 2, 2012)

That looks almost exactly like a motor I had fail from eddy current arcing through the bearings. Was this running on a VFD? I had a blower motor fail from this but I have yet to see a pump motor fail from this. The only difference I could tell between a standard bearing failure and the eddy current arcing was the pitting in the steel balls from arcing.


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## backstay (Feb 3, 2011)

Is the motor bearing rated for vertical? Smaller ones may not matter, but the larger motors need a bearing that can handle the down pressure.


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## chrisfnl (Sep 13, 2010)

No VFD, and no pitting. Very smooth consistent wear all the way around.

Not sure if it's rated for vertical operation, but I certainly hope so! We've got a number of these mounted to a number of generators, all installed at the factory by the oem.

Would that be in the spec for the bearing itself?


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## Southeast Power (Jan 18, 2009)

Was the sound it was making coming from the inner race bottoming out after the outer race was in that groove?

I think I would pull another motor and see if it too had any signs of this.

It would take some friction to cut that groove. You didn't mention any signs of heat. Is it possible that groove is supposed to be there?


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## CADPoint (Jul 5, 2007)

backstay said:


> Is the motor bearing rated for vertical? Smaller ones may not matter, but the larger motors need a bearing tha t can handle the down pressure.


One can easily use a long paper towel ring and place it you you ear and
isolate the sound, and surprisingly from a safe distance.

Any shifting shaft would could easily cause the motor to be out of OEM manufacturing specification and help to describe this failure. 

Most motor tolerances could easily be in the realm of .05 to even .005 of an inch, getting away from those numbers is a problem.

Do you think the motor was exposed to improper loading and usage?

You can have the metal fragments tested and qualify that in fact there the shaft, if in fact the OEM or their supplier wants to walk away from the motor.


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## John Valdes (May 17, 2007)

You have already cleared up any discussion of VFD and this looks like a small motor so there would be little if any need for a thrust bearing.
But I would inquire to the manufacturer if indeed this motor is designed to be run in this position. 
The next thing we would address is mounting. How much care is being taken as far as alignment? Just because your coupling has a rubber spider does not mean you are not exerting axial pressure on the shaft.
Alignment would be my major concern. :thumbsup:

Lastly. Now that you must replace this bearing and its evident the inner race of that end bell is out of tolerance, (it needs to be bushed and turned) you must take precise measurements using the bearing manufacturers tolerance chart to machine the end bells back to acceptable limits. Or you can use the OEM specifications as far as tolerances. I would use the bearing manufacturers chart.
This is very important.
Do not use locktite to repair the end bells. Have a machinist measure and repair the end bells properly. The shaft should also be checked for wobble and to check inner race tolerances. A good machinist will check all these things if he works with electric motors.

Note: You have to decide if this motor is worth repairing since its OEM.
You may be better off replacing it. Check new (OEM) price vs repair and decide.
Also, please include nameplate info. Especially frame number so we can look at any possible shaft modification.
Maybe we can cross it to stock?


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## chrisfnl (Sep 13, 2010)

Warranty replacement isn't a problem, new part is already on the way.

I'm more concerned about the life of the new motor, there's only 6 months warranty left on the system.

I'll get a few shots of the mount/coupling, I'm not quite sure how to go about aligning it, aside from making sure it's torqued down equally.


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## sarness (Sep 14, 2010)

Most likely it's not vertically rated, that much weight on a ball bearing setup can cause that kind of wear.

I've had horizontal shafts do the same thing from too much side loads. Swapped everything over to tapered roller bearings and much longer service time between now.


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## John Valdes (May 17, 2007)

chrisfnl said:


> Warranty replacement isn't a problem, new part is already on the way.
> 
> I'm more concerned about the life of the new motor, there's only 6 months warranty left on the system.
> 
> I'll get a few shots of the mount/coupling, I'm not quite sure how to go about aligning it, aside from making sure it's torqued down equally.


Get a shot of the nameplate while your at it. Make sure we can see the frame number if it has one.


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## chrisfnl (Sep 13, 2010)

So here's a few more pics, one of the name plate, one of the coupling, one of another identical motor installed...


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## chrisfnl (Sep 13, 2010)

Did I frighten everybody off with the iec plate?


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## John Valdes (May 17, 2007)

No not frightened, but it is an OEM motor.
Do you want to try and cross it to stock? Its right at 1hp and its a four pole motor.
But we have no frame? OEM does not want you to know what frame it's on. I do see an 80 in the long number....
If you want to try and cross it, get a pair of calipers and a ruler and look in any IEC motor catalog and find the standard IEC frame for a .75 kw motor at 1800 rpm. Its an 80 frame.
Take frame measurements using a standard frame chart like in pocket engineering handbook. See what you actually have vs an 80 frame.
It looks like a "D" flange BTW. (flange holes not threaded)?

As far as your bearing failure. Make sure you align the coupling half's and make sure you are not putting to much down pressure when you pull the motor down. Make sure you have measurable space between both coupling half's.

You don't have much you can do for alignment. You might want to consider a better ball bearing if you cannot pin point the issue.
Bearings do fail and that may be all it is. So replace with a very good quality bearing designed for the application and rated for hard duty.

I see the window, to look in for coupling alignment. Look at the coupling specs to see what tolerances you should be adhering to.


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## chrisfnl (Sep 13, 2010)

Flange holes not threaded, matching holes on the pump side are threaded. 

Not sure where you're seeing a window, might be a shadow, the coupling is fully enclosed once the pump is mounted. 

I'll have a look and see if I can find a frame number.

Hopefully it was an issue with the installation, could be bearing failure, but the bearings are surprisingly still quite smooth, given the condition of the race.

Found the data sheet, seems the bearings are 6004 2zc3


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## John Valdes (May 17, 2007)

chrisfnl said:


> Flange holes not threaded, matching holes on the pump side are threaded.
> 
> Not sure where you're seeing a window, might be a shadow, the coupling is fully enclosed once the pump is mounted.
> 
> ...


That tells you its a "D" flange.

I saw the cone shaped part that covers the coupling. There is no plate to remove to look inside? I guess more OEM trouble making.
If you have a machinist or someone with some skills for this, have him make an inspection cover for the coupling.

You are supposed to be able to leave the coupling loose from both ends of the shafts. The motor shaft and the machine shaft.
When you set the motor, you should be able to move each one up and down and to place it over the spider.
Then with using the coupling specs, set the clearance between the two coupling half's. This is important as you must be able to see and adjust the coupling. How do you know you are putting the coupling on the shaft in the right place? Get someone to make you a window. A "inspection door".

The motor is .75kw at 1800, which is on a 80 frame stock. There is an 80 in the number across the top. That tells me we are in the ball park and this might be a stock motor? But to be certain you will need to look at a stock 80 frame to see. You must check all frame dimensions. 

Now that I know you are mating the two coupling half's by luck? That you cannot see the coupling once the motor is installed, I will assume you have alignment issues or to much pressure is being applied to the coupling. You must be able to separate them on both of their perspective shafts to be able to have a measurable distance between the two coupling half's.

Using the bearing number, ask your bearing supplier if he can recommend a better bearing. Many years ago we used to buy what we called "Maxi Ball". They were rated close to that of a roller bearing. That would make it a superior bearing in comparison to a ball bearing. 
Good Luck and get into the cone so you can see the coupling once the motor is mounted. This is the only true way to be certain you have it on there correctly.


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## chrisfnl (Sep 13, 2010)

Much appreciated!

Motors are definitely where I'm weak in experience, I'll try what you suggested.


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