Need help identifying Baldor motor (ilder for phase converter)

[Deude-Mann]

Good afternoon all

I need help identifying this motor for bearing replacement.

Background:
I have a large surplus Baldor three-phase motor that is being used as an idler motor with a North America CF-30 phase converter panel. It is all installed and running, except that one or two of the bearings on the motor are howling when running. I have lubricated them through their grease fittings with the proper grease and there is still no improvement. The motor starts and runs fine except for the bearing noise.

Long story short I can return this motor with some hassle; the supplier is not local, and is a 250 mile drive one-way. I could also replace the bearings myself which may be the easier approach overall; the motor supplier has offered to pay for the bearings and labor. I have the tools and knowledge to replace the bearings as long as they are nothing strange and are readily available. However I do not want to tear down the motor to get the bearing numbers directly since the motor is under warranty so to speak.

The tiles in the photo are 12"x12".

Does anyone know how I can get a part number for this motor or the part numbers for the bearings? All the information I have is in the attached photos. Thanks

 

[dalmatiangirl61]

Tear it apart, the bearings will have numbers on them, electric motors use plain jane bearings available just about anywhere.

Edit: Is there no data tag? Sometimes bearing part#'s can be found on the data tag. If no data tag, how do you know what HP and voltage it is?

 

[Deude-Mann]

Again, I am avoiding tearing down the motor to get the bearing numbers since the motor is under warranty so to speak.

No data tag I can find. The motor was supplied with the phase converter panel. Would it be under the fan housing?

 

[dalmatiangirl61]

Typically it is riveted to outside of case. Maybe the supplier knows the part#? Without HP, voltage rating, and rpm, how did supplier match it to the panel? Without a motor part#, or bearing info from data tag, I see no way to positively identify the bearings without disassembly. Remove fan cover, remove fan, remove the 4 bolts holding endbells on, hopefully whomever installed the bearings did so with part# visible without pulling the bearings.

My WAG based on eyecrometer measurement of the pics is its a 6208 or 6308 bearing, common motor bearings, but that is just guessing.

 

[dalmatiangirl61]

In post 1, pic 2, the 4 bolts around bearing housing will need to be removed also, they hold a bearing retainer plate. You should be able to remove the endbells and leave the rotor inside the stator while replacing bearings.

 

[Deude-Mann]

You were right on with the bearing retaining plate. I spoke with the motor supplier, who is being very helpful, and said to go ahead and open up the motor. Here is what I found when I removed one side of the housing...




The bearing retaining plate also holds a seal against the backside of the bearing. The bearing has a large spanner type retaining nut holding it onto the shaft, with a bent tab style retainer locking the nut in place. I know roller bearings are incredibly precise things, and it does not take much for them to be damaged, but this one appears to be in decent shape. The rotation feels smooth and I do not see any discoloration or debris in the grease.
The bearing markings are:
FAG
KOREA
6311.C3
F0528-2347

I cannot remove the other side yet since there is a key that is stuck in the shaft; it is the key that drives the cooling fan. It is in rather snugly so I need to be careful removing it.

 

[rons]

I had a few whines in my time. Rotating a motor from horizontal to vertical when running.

Problems I fixed was not due to bad bearings. The washers and springs on the shafts were the issue. One time I shaved down a spacer a few thou. Sound of silence.

 

[dalmatiangirl61]

Most likely that key is a woodruff key (half moon shape), use a punch and smack one end and it will roll out, or use a pair of side cutters to grab it and lever it out, if damaged in removal its cheap to replace. Check endbells and make sure the bearings are not spinning in them. When you greased the bearings did it feel like they were accepting grease? Most likely both bearings are the same, but check before ordering.

Cheapest name brand set of 6311 bearings I'm seeing on ebay is here, no affiliation, check your local supply too, and make sure to ask country of origin. NEW SKF 6311K OPEN BALL BEARING | eBay

 

[dalmatiangirl61]

I had a few whines in my time. Rotating a motor from horizontal to vertical when running.

Problems I fixed was not due to bad bearings. The washers and springs on the shafts were the issue. One time I shaved down a spacer a few thou. Sound of silence.

I seem to remember making a thicker spacer once to fix a similar problem.

 

[johnoder]

Fun to know stuff - with the 55m bearing bore it likely has a 2 1/8 shaft - making the frame size at least 324

 

[neilho]

I'm with Rons here, could very well be that the noise isn't bearing related.

 

[BT Fabrication]

bearing numbers are ususally on the name plate on those.

 

[Deude-Mann]

OK one more related question. The bearings I found are sealed and I am inclined to leave them this way. After checking the bearing calculations per the manufacturer guidelines (SKS) the predicted service life of the bearing is good for 40 hours a week for 25 years. This is well beyond what I will use it for. No washdown, clean environment, light loading, climate controlled temperature.

So... If I leave the seals on, I am thinking I need to remove the grease seals that are part of the lubrication system. Correct? Here is one of the two. It presses on the inside race of the bearing on the opposite side (rotor side) of the lubrication inlet and outlet.

 

[Deude-Mann]

I seem to remember making a thicker spacer once to fix a similar problem.

Circling back to this comment... Are you talking about adjusting the bearing preload by shimming? This one has a wave washer for the bearing preload.

 

[dalmatiangirl61]

Circling back to this comment... Are you talking about adjusting the bearing preload by shimming? This one has a wave washer for the bearing preload.

It was an older style motor that used a washer as a spacer, it had worn too thin. Just use the wave washer as intended. The sealed bearings should be fine, its what I used in rpc, after having to clean out the excessive grease that had been pumped in over the years in an attempt to quiet the bearings. If the grease seal gets in the way, remove, or just put it back in if not in the way, let the next owner ponder why

 

[Deude-Mann]

Thanks. Yeah with just a washer for a shim I could see that being an issue. It sure would not take much wear to throw the preload off.

I'm going to remove both seals and retainers, and even though I'll probably have this motor forever, I'm going to remove the grease fittings and put a 'no grease' label or something like that on it.

 

[Deude-Mann]

OK, follow up...

I heated the new bearings at 200F for about 24 hours to expand them and they both installed easily onto the room temperature rotor shafts. The larger 55mm bore bearing slid right on; the 40mm bore bearing needed a few light taps on the inner race using a sleeve tool I 3D printed.

The motor reassembled with some gentle tapping on the housing end caps with a dead-blow hammer; the bearing outer races were a nice close fit with the end caps. I considered heating the end caps to expand the bores but it was not necessary. After incrementally tightening and torquing the housing bolts I started up the motor and the bearing howling was gone. Now it is nice and quiet with the normal hum one would expect from a 3-phase AC motor. I ran it for about 20 minutes (no load) and everything sounds fine.

Since I mentioned it above, I elected to install it with the seals on the bearings, and removed the grease retainers from the motor.

Mission accomplished. Thanks for the input.

 

[Deude-Mann]

The motor running before the bearing replacement
[video]https://photos.app.goo.gl/3hKWu9gSWLrXCtMB8[/video]


The motor running after the bearing replacement
[video]https://photos.app.goo.gl/ZLZJbBdnREyw4vA87[/video]

 

[Bill D]

You say roller bearings with precise preload. The one shown looks like a ball bearing to me. Since there is no load on this device the rotor can float a bit axially.
Bill D

 

[Deude-Mann]

Sorry, I should have said ball bearings.