heavy bearing grease 1

[duk748]

hello - i have a situation in a existing design that has 2 taper roller bearings on a shaft mounted to a single housing - there is no room on either side of the bearing housing to put a grease seal to keep the grease from seeping out - the grease will stay inside of the housing but will seep out on the out side of the bearings - i thought i have seen a particular bearing grease that is heavy or like a wax type substance - sort of like motorcycle chain grease that will not attract dust, dirt or water - it will stay put on the chain - any help or suggestions would be greatly appreciated - thank you

 

[MintJulep]

Grease is oil bound in some sort of goop. The goop used to be soap, but these days is probably something similar.

A properly selected grease works by allowing the oil to separate out of the soap to allow it to lubricate.

So with no seal, it's gonna' seep.

A not grease might work. Something like Dow Corning Molykote G807 or 112. But it's really very dependent on loads and speeds and temperatures. Talk to the tribologist from the bearing manufacturer.

 

[dvd]

I've designed applications with bearings that had no seals. The bearings were constantly supplied with fresh grease via spring-loaded lubricators.

 

[rmw]

I might take a different tack here than Mint. The soap is a carrier of the oil component of the grease. The oil is the lubricant; soap the carrier. Common carriers include lithium soap, calcium soap among others. Go to any reputable grease manufacturer's site for a complete list.

The grease which as said above is oil carried by soap is designed to flow in and out of the bearing as the bearing works and is heated by the work. This not only keeps the bearing supplied with a fresh supply of oil, it cools the bearing. If the grease is too thick, it can't flow. If it can't flow, it can't lubricate and cool.

After a time, the soap and the oil break down - separate, and the depleted soap has to be pushed from the bearing by fresh grease.

Some bearing housings have tubes located high in the housing for the spent grease and oil exit point, and some just push it out past the seals.

In theory if the grease never wore out (broke down) it would just stay in there forever and do its thing. Unfortunately the world doesn't work that way hence the need to re-grease bearings to replenish the depleted grease.

Specific soaps and specific grades are recommended for specific bearings and specific applications. Your bearing manufacturer can provide you with what type or types of grease is required for your bearing and application and any alternate grades that might suffice.

Your job is to put the bearings in a housing where they can be properly lubricated, or use a sealed bearing which works as described above and keeps its grease contained inside (until the grease and soap separate when you will have to replace the bearing.)

Using a grease too thick or stiff can and will result in a bearing failure. I suspect you can find pictures on the net somewhere of bearings that are blue completely surrounded by new virgin grease that has never entered the bearing. If you can't find any, I can send you some if I can dig them out of my files.

This is not new science. You can probably find the above description on any reputable grease manufacturer's site, especially if they make grades for bearings.

rmw

 

[duk748]

hello again & thank you for the help - i appreciate the info & i understand how things should work when properly done - this design is very old & our department was asked to help find some alternatives to the problem of the grease seeping out after time - if the space was not so tight you colud put a seal or seal retainer on each end but no one to this point has be able to come up w/ something - as always this forum has some great people on board & i thank everyone for there help & info - just looking for some other ideas

 

[Tmoose]

Hi duk748,

Don't even have room for these ?

http://www.bearing-king.co.uk/data/images/3837.jpg

this wouldn't be a conversion from loose balls to TRBs on some motorcycle component, would it?

Dan T

 

[duk748]

hello again & thank you for the help - yes these i believe are nilos rings - i have found these & have contacted the manufacture
great find & i thank you - unfortunately no not for a bike (wish it was!!) - still in the saddle but no time for riding anymore - hence my handle duk748 (my last ride was a ducati 748) - miss that very much!! - once again great help here - nice people too - have a great weekend

 

[Tmoose]

I bought a non-Harley US made motorcycle ca 1974 and they had those integrally sealed Taper roller bearings . First and only time I have seen them