Posted on behalf of Dale Thrasher, Line Mechanic

How often and how much grease should I put in a bearing 8 feet in diameter and 4 inches thick? There are 8 grease points on it; rotating 7.5 times per minute. Operating 24/6 for production and humid area with temperature of 95 degrees. This is a carousel ball bearing; some grease always seeps out the seal.

Dale Thrasher

This is a slow moving large diameter rolling ball bearing. What is unknown is the characteristics of the OD and ID mount. Each ball is rolling 3 times a second or traveling 3 feet per second. This seems to be a low rate and so not much heat is being built up in the races. Grease is a oil lubricant mixed with a soap to fix it in location. Thus putting grease above the seal ID line would result in seepage. How often due you grease the bearing? Do you use and ultrasonic grease gun to determine if enough grease is in the roller path? What is the function of the eight tap points on the bearing? Perhaps a phone call to the manufacturer and designer of this bearing is in order! Questions to ask, 1.) Can ultrasonic grease guns be used to determine proper grease application? 2.) What is their expectations of maintenance on this rolling element? 3.) Should the old grease soaps be washed out on some periodic time frame and how should the flushing be carried out? 4.) Double check the grade of grease recommended! 5.) What parameters does the designer use to determine that a bearing of this type should/need to be replaced?
Ralph 651-388-1121

With this type of application is will be important to monitor the used grease to see what is occuring in the bearing. We don't think VA will offer good info @ this slow RPM.

To start pre pack as per the bearing makers instructions, this should work well and we don't want to void any "warrentees".

When the bearing is being installed it is very important to ensure there is a grease relief path so as the lubricant is applied there is an easy path for the used grease to escape and this path must be through the rolling elements so used grease is removed from the loaded area and as the used grease escapes samples can be taken and the used grease condition monitored.

We think the new grease should be applied via an auto greasing system as this will apply a continuos film of new lubricant removing any wear debris generated from the load zone off the rolling elements flushing to the sample point allowing accurate trending of the application.

We think the applied grease should be a Calcium Sulfonate with passive EP, base oil > ISO 400, this is avery firm stable grease and seepage would be nil to minimal,
mineral oil should be OK as the grease will be continously replaced by the auto greaser.

Exon/Witco make this product I think it is called WR 2500.

This should be monitored by microscope, we would filter @ 11 µm and then again @ 3 µm and the amount of grease being applied is decided by the amount of black oxides and wear debris generated, we increase the grease flow until there is normal rubbing wear debris being produced and the amount of heat damaged lubricant is acceptable,

Hello, I just joined the sight and saw this post. In answer to your question of how much grease is required of an 8 ft. dia. bearing that is 4inches wide , use the SKF formula bearing O.D.(in inches) times the bearing width times .114 (O.D. X W X .114) this will give you the quantity of grease in ounces by wt. required for initial lubrication. based upon the speed quoted for this bearing I would think that re-lubrication should only require about 25% of that amount based upon SKF recommendations. The answer is 43.7 oz. of grease on initial lube and 10.9 oz on re-lubrication. If you are using a high quality grease and enviromental heat is not a problem then I should think that regreasing on a semi-annual basis is sufficient according to skf recommendations. SKF also recommends that the grease be replaced every 3 re-lube intervals, I however do not necessarily agree with that recommendation. I would monitor the bearing with a lubrication analysis every 6 months. If the seals are in good shape and contaminants don't get into the bearing, it should provide years of trouble free service. I hope this has answered a few of your questions. Most of this information can be found on the SKF websight.