I have a little project that I'm currently thinking about, and I'd like a bit of info from those "people who know useful stuff".

* I want to make a cover that will rotate, with a stationary shaft going through the middle.
* I do not want any dirt, dust or water to go through the gap where the cover meets the shaft.
* The shaft and cover will be unlubricated.

What do you define as "dirty envronment"?

I had a set of sealed jockey wheels (those ickel wheels on the rear gear shifter on moutnain bike) and they didn't last too long; less then the standard jobbies.

Water got in and seized the bearings.

If you look up the seal specification e.g. on RS, then maybe that would give some info.

Oh, just another thought. The bottom bracket on bikes is a sealed affair that can see mud, water etc. and they last quite a long time, several 000s miles.

I suspect my jockey wheels were not as well sealed; can't recall if they had metal or rubber seals.

[Edited on 20/11/08 by 02GF74]

Similar (same) question; I want to make a little gearbox, would a sealed bearing stop oil leaks? (bearing to housing & bearing to shaft can be loctited)

BTW the metal seal ones are described as "shielded" rather than "sealed"

[Edited on 20/11/08 by Bob C]

how big does this seal need to be?

i would be looking at valve stem seals, possibly off a tractor/truck if car ones too small.

or motorbike fork dust seals are fairly good.

i cant see how the seal on a bearing will be any better than just a normal seal.

Wil

i know bearings we use for rc car racing, rubber sealed, ptfe sealed, and metal sheilded. none of which are water tight or dust proof, but do keep a lot of gunk out, however running them without seals they last only a couple of months due to the dust that gets in

Try THESE guys, very helpfull and all bearings have online specifications.....

Hi

Might be worth looking at how prop shafts on boats are sealed ......... or if you want to think out of the box ...... air bearings.

Regards Mick

Dirty environment = front wheel hub. Loads of dust, mud, and occasional spraying with water.
How big? = 8mm dia internal fixed shaft, don't care about the outside of the seal/bearing as long as it's not too big.

Rubber sealed bearings are pretty good. The metal ones are more for higher temps or high speeds, but they still have very good seals.

From SKF you would be looking for RS1 seals (which are the plain rubber seals) or RSH seals which are the full contact seals and ideal for dusty and wet environments. These letters are found at the end of the brg description e.g. 607-2RSH

David

As above , I work in a food factory and machinery gets pressure washed each day, the rubber sealed bearings last well unless directly jet washed.Sometimes we have fitted plastic shields to avoid direct jet washing.
The same bearings could be used to retain oil in a gearbox and infact often are on light machinery gearboxes.
Paul

quote:

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Originally posted by flak monkey
Rubber sealed bearings are pretty good. The metal ones are more for higher temps or high speeds, but they still have very good seals.

From SKF you would be looking for RS1 seals (which are the plain rubber seals) or RSH seals which are the full contact seals and ideal for dusty and wet environments. These letters are found at the end of the brg description e.g. 607-2RSH

David

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Thanks! Exactly what I needed to know!

(I've always said that there is always someone who knows stuff on this site...)

What type do you need? I have a few 61905's with seal on one side, shield on other (ID25, OD42 x 9mm thick) and also a few 6203's sealed both sides (ID17, OD40 x 12 thick) that you can have to try.

Also have some small 626Z's but they are shield both sides (ID6, OD 19 x 5mm thick) - probs no good. Ideal for drawer runners.

i should have said the science behind bearing maunfacture ican be quite daunting. Even when bearings are sealed there are different spec seals used and also they can be manufactured with varying torque to rotate specs which indicates how hard the seal contacts the bearing faces (and other factors too deep for discussion).

The 61905's i have are quite tight, you can feel the red seals in good contact. the 6203's are blue seals and feel less tight.