How to protect a bearing from the elements

[shaeff]

Yeah! What in the world is a (hand crank trap kit)?

My best guess, maybe talking about skeet shooting?

 

[mcfarmall]

Here's my take on the matter. A shielded bearing has metal shields that ride very close to, but never touch, the inner race of the bearing. Shielded bearings are designed to keep large particles out of the bearing and are typically specified for higher speed applications >3500 rpm or thereabouts. The metal shields can be removed if needed such as in an oil filled gearbox or on a greasable electric motor. Rubber seals in high speed applications will overheat and fail, this is why you'll find shielded bearings on your Porter Cable 690 woodworking router.

Sealed bearings are designed for lower speeds <3500 rpm and have rubber lip seals that contact the inner race. Good for keeping dust and moisture out, but they aren't submersible. The rubber seals can be removed and re-installed at will or if you want to pump a little grease in there down the road.

So back to the OP question of slathering some silicone (I presume RTV silicone sealant) on the topside of the shielded bearings, I'd say no. Simply realize that just like the belt idlers on your mower deck, they will be replaced a little more often due to their inherent design and move on.

 

[IH3444]

Try using a high quality synthetic marine grease which repeals water to pack the shielded bearing with.

 

[Egon]

About the only way to properly seal a bearing is to have a positive pressure system in place.

 

[mitch becton]

okay to answer first and seems to be the most foremost question about my statement tarps systems on trucks and other equipment are e 12v electric motor driven .Small 5 yard trucks and trailers use the true hand crank to move the tarp from front to rear and back to somewhat secure the load i am doing for these for state road dept and they have about 30 of these in service now and having sold many bearings in the last 53 years the metal shield by far is better for extreme exposure not only is it oil resistant and most any element mother nature throws at it. and by the way the tarp kits i am working on are mostly only used on salt trucks. The interior of bearing requires only a very small amount of grease mostly the ones sold by chevron the rubber seals will shrink to a point they let the elements in the metal seals have very little room for shrinkage and as someone has mentioned true bearing that are run in oil all them time 1 side is exposed to the oil to keep in running cool the other side is mostly metal sealed.

 

[CalG]

Just a note of comparison.

Automotive practice for "front of engine" ancillary elements such as water pumps, alternators, fan pulleys and belt idlers is to use SEALED bearings. One never sees shielded bearings for these applications.
RPMs can easily exceed 3500,

My choice for nearly any application is double SEALED.

Just an anecdote, and not relevant to environmental exposure, but.... In my younger days, I built a racing motorcycle with a two stroke engine. I used Double SEALED bearings on the crankshaft to better "stuff" the crank case in efforts to improve flow and breathing. The particular engine had "direct oil injection" for the crank bearings, but still required a light oil gas mix to assure lubrication to the piston skirt etc.
Sealed bearings would seem contrary to an open lube system that easily exceeded 10.000 rpm. The bearings served for several years. They even survived a top end piston failure without a hitch. Perhaps the rubber seal lips burnt away due to friction and heat, but even then, the DOUBLE SEALED bearings were no worse than SHIELDED bearings.

For me, Sealed bearings are a first choice.

 

[Spanner]

... i am doing some work on hand crank trap kit all the bearings...

okay to answer first and seems to be the most foremost question about my statement tarps systems on trucks and other equipment are e 12v electric motor driven .Small 5 yard trucks and trailers use the true hand crank to move the tarp from front to rear and back to somewhat secure the load i am doing for these for state road dept and they have about 30 of these in service now and having sold many bearings in the last 53 years the metal shield by far is better for extreme exposure not only is it oil resistant and most any element mother nature throws at it. and by the way the tarp kits i am working on are mostly only used on salt trucks. The interior of bearing requires only a very small amount of grease mostly the ones sold by chevron the rubber seals will shrink to a point they let the elements in the metal seals have very little room for shrinkage and as someone has mentioned true bearing that are run in oil all them time 1 side is exposed to the oil to keep in running cool the other side is mostly metal sealed.

TARP kits!! You wrote Trap kits!!! No wonder we were confused.:confused2:

Not saying I would have immediately known what a 'Hand Crank Tarp Kit' was ... :ashamed:

Thanks for clarfying Mitch.

 

[Egon]

"From past experience, the metal shield is better than rubber. This is because the metal shield is designed to run oil, which is much more of a sealer than it's rubber counterpart. I am doing some work on hand crank trap kit(?), all the bearings are exposed to the elements at all times. Does anybody else understand this to be true?"
Fixed?

For this type of situation step back a few years and use greaseable wooden bushings.

 

[shaeff]

For this type of situation step back a few years and use greaseable wooden bushings.

I was just "translating"- I have no opinion on bearing types or seals.

And Mitch- Tarp kits, gotcha!

 

[dieselscout80]

For this type of situation step back a few years and use greaseable wooden bushings.

This idler pulley is on a diesel engine, so I doubt a wood bearing would last even one day.