Sealed Ball Bearings - Truly Sealed ?

[wgknestrick]

I am designing a individual throttle body and using double sealed bearings for the shafts. I must be able to seal +35psi and 30in vac through the bearing. I just don't have much experience with bearings and cannot find an answer on this anywhere.

Is this possible with just a double sealed bearing or will this require an O-ring? I'd like to avoid an O-ring if possible, because resistance will be critical in this application.

Any guidance is greatly appreciated.

Bill

 

[gerhardl]

.. I'm not able to visualize in my mind your construction, but:

a) The ball-bearing supplier should be able to answer your question, given the necessary details to specify a certain ball bearing commercial available. (There's quite a few to select from out there..)

b) Is your construction such that a rotating joint would be a better solution?

 

[wgknestrick]

http://users.rcn.com/wgknestrick/roller barrel ass'y SECTION.jpg

Here is what I am working with. Roller barrel throttle body for a Subaru engine. Pressurized intake volume is inside the "2 ports" and this needs to be sealed from ATM through each bearing that supports the roller barrel. You can also see my provisions for O-rings (if needed) to seal the ends of this throttle.

 

[wgknestrick]

http://users.rcn.com/wgknestrick/roller barrel SECTION.jpg

 

[btrueblood]

The seals in sealed bearings are generally only there to prevent grease from leaking out during operation, not to support any significant pressure differential. You need a seperate seal (O-ring or similar).

 

[wgknestrick]

That's what I figured. I think they could support some pressure, but I was just fishing to see if anybody has quantified it.