I have a question concerning how one would determine while looking at an FFT spectrum, when the oil level would be over filled, or under filled in an SKF split pillow block bearing with spherical roller bearings? Since you really cannot see real good at the bottom of the housing where the oil level is, at the 6o o'clock position on the roller bearing...

We have alot of our people here installing bearings, and they are guessing at the oil level adjustment...Had a problem or two in recent years where the oilers we set too low, and the bearings burned up...!

Any suggestions, or links on the web where I can research this? About all I know is how to detect oil whirl at sub-running speeds.

Thanks,

R. Bell

I'm not expert in lubrication but I thought don't you need to top up until half full on the sight glass and this level will drop once the machine running ie after the oil film is formed? Did your operator complain the bearing oil level is low while the machine is running?

These bearings don't have sight glasses. These are all SKF split pillow block bearings with self feeding oil bowls, and adjustment trees...
Unless you can actually see the bearing rollers while putting the oil in, it's more or less guess work..If oil leaks out after start up. then you have to crank down the level adjustment.

R. Bell

SKF_Housing.JPG (13 Kb, 25 downloads) SKF Housing

For gearbox? Ask SKF who is the designer then...

All our gear box's have sight glasses, as well as our Gould Pumps.

RB

RB,

It is important for the mechanics installing the bearings to make a mark on the outside of the bearing housing, that corresponds to the height inside the reservoir where the oil will be at 1/2 the height of the roller element at it's lowest point of travel. This is the standard oil height level for rolling element bearings, but check with the vendor manual just to be sure that this particular bearing configuration calls for that (sometimes recommended levels are lower than that, with the presence of a flinger or oiler ring, for example). Then using that mark on the outside of the housing as a guide, a bubble-level must be used to extend that out to the position of the oiler cup, where a mark is similarly made. Then the wing-nut adjustment can be made to position the bottom of the oiler ball opening at this height.

Seems like a lot, but it is necessary to ensure proper lubrication. In some bearing arrangments, an access plug can be removed and the bearing can be seen visually while in operation using a boroscope (I don't think you'll be able to do it with these pillow blocks. I had done this on several critical pumps and found that the standard settings being used by the mechanics (and measured from the pedestal or stand of the pump) was off by about 3/8", which was sufficient to completely starve the bearing of oil. We visually watched the oil level in the housing while adding level at the sightglass, and were able to determine exactly where the level should be while running. We marked this point, and adopted an acceptable range that would provide adequate lubrication. We then turned the pump off, and found where the shutdown level settled to after cooling, and marked and labelled that as well.

If there is no visual access, and you want to confirm proper lubrication, then I would use ultrasound rather than vibration. It is fairly easy to differentiate the dB levels of a lubricated vs. dry bearing. It is quite a step change in amplitude. You need to baseline the particular bearing type and application, and then look for significant increase in the dB level as indication of either bearing damage or loss of lubrication.

Hope that helps.

Rich Wurzbach, CLS
rwurzbach@mrgcorp.com
MRG Power Labs

A few years back we made a database on the oil levels of our various sizes of housings, by putting the bearing housing level on our table in the office...This included the pipe nipple, & oil level w/tree...

We leveled the housing and the oil leveler, then filled the adjustment tree holder until it stabilized 1/2way up the bottom bearing roller like you were talking about...After this we measured the distance on the tree stem. We documented this on all housings up to the SKF 628 size...We also used the SKF book for all the measurement points on the housing. I wrote up a set of procedures on this with the attached drawing, for the mechanics, but no one uses the info unfortunately...

We also devised an adjusment block with two small adjustment bolts so we could raise the pipe nipple to the level position. This has worked well...

The ultra-sound may be the way to go, but I'm not familiar with this method. I'll have to do some reading on this...

Thanks,

RB

Oil_Leveler.jpg (10 Kb, 26 downloads) Oil Leveler

Just going outside the box here. What about using MATH? You have a known cavity volume and a fluid with a set specific gravity. Couldn't you do a volumetric mass equivalent and weigh out the appropriate fill volume?

Secondly, the bearing manufacturer (SKF) has great pull with the constant level oiler manufacturer. Call SKF and have them give you the proper lube level. I worked for a manufacturer of Constant Level Oilers and we did this calculation about 3 times a week for SKF, FAG, Timken and quite a few other companies. We never heard back and in engineering, no news is good news!

Hi RB,

We are using Ultraprobe Grease Caddy-201 for determining the Overgreased/Undegreased bearings. I think the same thing you can use for oil lubricated bearings also. It is just a headphone connected to a sensor through an instrument showing the db levels. Very handy and uselful tool!!

Have a nice day!!

Here is the link to Ultraprobe grease caddy:

http://uesystems.com/prod_up_201.asp

Article on Constant level oilers:
http://www.machinerylubrication.com/article_detail.asp?articleid=821

Is the pillow block bearing not self-lubricating?
http://en.wikipedia.org/wiki/Pillow_block_bearing

Lubrication for SKF plummer block roller bearings:
http://www.skf.com/portal/skf/home/products?paf_dm=shar...ng=en&newlink=6_2_39

What is your application? Trucks?
http://www.skf.com/portal/skf/home/solutions?contentId=...001112.004102.000792

Whatever, this maybe is the info you need:
http://www.skf.com/portal/skf/home/products?paf_dm=shar...ng=en&newlink=2_6_14

I've been wanting to use ultrasonics to check on the lubrication within the bearings. We have an SKF 400 series ultrasonic gun, and my ear muff headset just came in last week, so I'll be delving into that...Guess I'll need to locate some sort of chart so Ican have a baseline on the db levels...

Rod

quote:

Originally posted by Jenish:
Hi RB,

We are using Ultraprobe Grease Caddy-201 for determining the Overgreased/Undegreased bearings. I think the same thing you can use for oil lubricated bearings also. It is just a headphone connected to a sensor through an instrument showing the db levels. Very handy and uselful tool!!

Have a nice day!!

Hi Josh,

Sorry to be slow in responding....Been very hectic here of late.

I'm hopping a plane to Midland, TX at 12:00 today to go to our other plant and train someone there to take readings, and work with the Machine Analyst 3.1 software...Seems our guy out there is out with a bad back...I'll be back here in Baton Rouge on Friday.

I'll monitor the vibration forum from my laptop...I want to look at these links you sent...Thanks for the input and the efforts...

Best Regards,

Rodney

The sealed bearing are, which we use on conveyors, and in our shipping dept. but we use split housings, and double row spherical roller bearings on our fans, which require lubrication.

Rod

quote:

Originally posted by Josh:
Is the pillow block bearing not self-lubricating?
http://en.wikipedia.org/wiki/Pillow_block_bearing