pillow block bearing failure

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I am experiencing pillow block bearing failures in our cooling towers. the bearings support 6 blade fans. driven by 75 hp motors, 8 rib belts. (vertically mounted) 3" shafts
The manufacturer recommends greasing these quarterly with Mobil 28. The manual states"grease until a small bead of grease is seen at the edge of the seal". I had the field rep on site last week, and he also recommended that method, and said anywhere from 25-30 shots of grease.
here lies the problem. None of my millwrights will agree with the recommendations. They do not agree with greasing until you can see it?
However, I have seen two failures, on two seperate fans. Obviously what we have been doing, is not working. ( 3-5 shots) per quarter. The bearings were installed 6-14-04, greased quarterly. Very wet conditions in cooling towers.
We do not have remote monitoring capabilities yet, and it is too dangerous to monitor while running.
I would like to hear opinions?
Thanks,
Rob

4/15/0510:53 PM

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buckhntrMember

Training and Leadership. 3-5 shots of grease per quarter in a pillow block bearing on a 3" shaft is not nearly enough even if it were not located in a high stress environment like a cooling tower. Regardless of what your millwright/mechanics think is correct, you should base your regreasing quantilty on appropriate DN calculations. Water washout will be a concern in this application and a good water tolerent grease should be used. If you can run remote lines to the outside of the cooling tower cell you could apply grease more frequently (weekly or monthly). Install a purge valve in the bearing also to relieve excess pressure. Your regreasing strategy might inclulde pumping enough grease in to completely purge the bearing housing to drive the water out. The relief plug will help prevent problems associated with overgreasing.

4/19/056:01 AM

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jonasMember

These are tough applications. You are probably using a lithium or lithium complex grease available through most major oil companies. These are unacceptable for pillow block bearings. L and LC have little resistance to water. Contact your local Schaeffer Oil rep or email me. Schaeffer's has solved this very problem for a number of pillow block users. Their Aluminum complex thickener base is 100% waterproof and will hold up much longer. You can also find some success with a polyurea based grease but that is totally incompaatible with L and LC greases and could cause problems if it ever found it's way into other bearings in the plant.

5/13/052:29 PM

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deanmaierMember

What is the speed of the shaft? Many applications if running too fast may get longer life if run in oil instaed of grease. Generally for a bearing with a 3" shaft that will be if it is approaching 2500 RPM.

Your best results will be with an automated system, that way it will apply a small amount often and be able to maintain the film required, as well as use a small excess to flush the contaminants. I have done many fan applications in kilns and cooling situations and the results have been dramatic.

Dean.

3/28/067:15 PM

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hawkMember

I agree with the above procedures of application in this situation, however you probably should contact the engineers at this company
www.huskey.com
I have encountered many situations involving pillow block bearings in a high moisture situation. What I have found is that all the commercial greases from the majors are "Water Resistant" not "Waterproof" (correct me if I'm wrong forum members)The huskey Co. has at least two products that I have used in these situations thaat have worked extremely well. What I would recommend is that you go to thier website, call thier engineers and discuss your situation. They supply most of the major Hydroelectric operations in the U.S.
I also have used these products to great advantage in the marine and fishing industries in both Florida and California. Also I have used in water immersion mining operations.

4/7/067:53 AM

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rttechMember

G'Day Hynix,

All the answers so far have good info and as the info states all the grease choices have compatibility difficulties so with me being reluctant to do any more work that necessary I'm inclind to shorten the greasing duration and reduce the amount as BuckHntr suggests as then only one thing is changed, the condition of the grease being expelled can then indicate whether the weekly grease can be extended but a couple of pumps per week wiil keep a steady flow of clean new grease thru the bearing.
Reagrds Rob S

4/9/062:11 PM

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hawkMember

rttech,

With the LVI50 or the Lub-o-Seal from huskey, both being synthetic silaceous base there should not be a compatability problem. Whenever I ran into a Lithium or Lithium 12 base that was being used, I just had the customer keep adding new until the old was out. Primarily the waterproof abilities of the new are a little dilute. However the ability of both of these products to adhere to any metal parts overcame any problems with the mixing and loss of protection.
Once all you get out is clear, you can cut your grease times at least in half.
Being in OZ may be a problem with quick delivery, but in the long run, in a wet situation this may save you time & money. However still check with the engineers to verify all of my spiel.
Sorry about my grammar last time,I sounded like a martian. What you get for typing too fast.
Regards
Hawk

4/9/065:13 PM

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lubtechMember

Dear Hynix,

For pillow block bearing lubrication always people recommands water resistant grease. I surprised you used Lithium grease which is not so good to resist moisture. There are many options are with you like silicon, bentonite, polyurea or calcium complex. Slicon is quite costlier affair, I suggest you polyurea base grease which not only resist moisture & water but also being non carbonizing.

To know more about the grease you can mail me on romesh_enjoy@indiatimes.com

Romesh sawant

4/16/069:30 PM

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