RE: front bearing, zz or rs shield??  
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RE: front bearing, zz or rs shield?? - 3/19/2006 4:04:42 AM   
Kweasel


 

Posts: 1087
Joined: 1/7/2004
From: fort worth, TX, USA
Status: offline 		OS knows its engines will be used casually with out being thoroughly flushed after use. Since they now offer a three a year warranty they are paying for corrosion related failures. A common and cheap sealed bearing buys the company some time and is more cost effective than stainless steel.

(in reply to cu. in.)
       Post #: 26

RE: front bearing, zz or rs shield?? - 3/19/2006 5:00:36 AM   
loughbd


 

Posts: 2111
Joined: 11/29/2003
From: Bremerton, WA, USA
Status: offline
quote:

ORIGINAL: Kweasel

OS knows its engines will be used casually with out being thoroughly flushed after use. Since they now offer a three a year warranty they are paying for corrosion related failures. A common and cheap sealed bearing buys the company some time and is more cost effective than stainless steel.


OS has never used a stainless steel bearing except in four engines The FS60, FS75, FS80, and FS90. It was the 15x20mm bearing used on the camshaft.

Little hard to be cheap and cost effective by not using stainless bearings if you never have. Very few if ANY companies use stainless bearings. If your read the warranty on an OS engine it doesn't cover rusted bearings and damage caused by rusted bearings. That comes under the heading of neglect so it doesn't cost the company anyway as they wouldn't cover rusted bearings under warranty. Seems like everyone is bad mouthing OS these days. Still the number one engine maker in the world. Been around 70 years.


(in reply to Kweasel)
       Post #: 27

RE: front bearing, zz or rs shield?? - 3/19/2006 8:32:20 AM   
asmund


 

Posts: 1909
Joined: 11/20/2005
From: Floroe, NORWAY
Status: offline 		thanks Ed: your top post on this page makes sense. I had just reinstalled my asp(was switching back and fourth my asp and mvvs 49 to compare) when this happened on the first takeoff, maybe I just had a kink in the lines somewere, but it did make me aware that my bearings was going bad anyway. I`ll be back

(in reply to Kweasel)
       Post #: 28

RE: front bearing, zz or rs shield?? - 3/19/2006 10:33:27 AM   
Ed Cregger



Posts: 7746
Joined: 1/31/2002
From: Ringgold, GA, USA
Status: offline 		Also keep in mind that silicone fuel line grows with exposure to model fuel. It is also possible that your fuel pick up line has grown enough to be forcing the pickup weight against the back of the fuel tank's wall. Good luck.


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(in reply to asmund)
       Post #: 29

RE: front bearing, zz or rs shield?? - 3/19/2006 11:09:39 AM   
DarZeelon



Posts: 7108
Joined: 4/9/2003
From: Rosh-Ha'Ayin, ISRAEL
Status: offline
quote:

ORIGINAL: Flyboy Dave

The rubber shielded bearing is always superior to the metal shielded, or
the plain ball bearing.


Dave,


There are several engine manufacturers that don't necessarily see things as you do.

Webra and Rossi are among them. They use a front bearing that is neither shielded, nor sealed.
It is a fully open bearing that has nothing to seal the fuel/air/oil inside the crankcase.

It is the crankshaft's job to seal the crankcase.


A bit strangely, the front bearing in these engines, although open, is not even more susceptible to dust, sand, other FOD than are sealed and shielded bearings, in other engines...

If the engine's manufacturer thought his engine was designed too loose to use open bearings (...), do use a bearing with the same type of seal/shield as the original.

If your engine had an open bearing, I would not recommend substituting a sealed bearing for it.
If anything, the engine's designers knew a thing, or two about this engine, to select the right type of bearing.

Don't second guess them.


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(in reply to Flyboy Dave)
       Post #: 30

RE: front bearing, zz or rs shield?? - 3/19/2006 5:02:41 PM   
Flyboy Dave



Posts: 13467
Joined: 3/20/2002
From: San Bernardino County, CA, USA
Status: offline 		I see you found something to nit-pic about. The fact is the Rossi's, Webra's,
and the open bearing racing engines have better quality control and tighter
clearances, so the crankshaft/crankcase seal is satisfactory. The Rossi
uses a tight fitting prop hub that fits over the front portion of the case
and probably seals the front of the engine almost as well as a metal shielded
bearing.

Super Tiger uses a full blown rubber seal on some of their engines for a
total 100% seal, at all times. Asp engines come with rubber seals. Some
OS engines are using totally sealed bearings now.

It not second guessing to install an improved bearing with a better seal
in the front of the engine....where either too much fuel is pouring out, or
an air leak is causing problems.

I've been using rubber shielded bearings in my rebuilds for many years, and
it works fine.

Do you have a problem with that ?




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(in reply to DarZeelon)
       Post #: 31

RE: front bearing, zz or rs shield?? - 3/19/2006 6:24:54 PM   
DarZeelon



Posts: 7108
Joined: 4/9/2003
From: Rosh-Ha'Ayin, ISRAEL
Status: offline 		I am nit-picking about nothing, Dave and I resent that attitude.

If an engine of a high quality (tolerance control, actually) that has a good crankshaft seal, has its open bearing replaced with a sealed bearing, it gets seal friction, where there was none before and the seal is none better...

I don't think there is anything "always superior", as you wrote, in a sealed bearing...

It depends on the specific engine you are looking at.
The sealed bearing is only superior, if the engine had a 'runny nose' that was fixed by its substitution for the non-sealed original bearing.

_____________________________

Dar Zeelon - ISRAEL - ddzeelon@gmail.com
MVVS - Jett - Nelson - Bolly - Mejzlik

(in reply to Flyboy Dave)
       Post #: 32

RE: front bearing, zz or rs shield?? - 3/19/2006 9:54:34 PM   
loughbd


 

Posts: 2111
Joined: 11/29/2003
From: Bremerton, WA, USA
Status: offline 		You guys should read Clarance Lee's Book, The R/C Model Egine. It has a good write up about sealed, shielded and open bearings and a great description on how they work. What he writes is pretty much what Dar Zeelon and MOST engine types feel about the bearing issue. AS do I.

I would think that a guy like C. Lee who has been designing and writing about model engines for over 50 years knows what he's talking about. He designed the K&B61, the K&B 40 and the Veco 19. Funny, these were great engines and they came with open bearings and later with just shielded bearings. But what would he know? Right???

Again read what he says about bearings.

(in reply to DarZeelon)
       Post #: 33

RE: front bearing, zz or rs shield?? - 3/19/2006 10:23:00 PM   
speedster 1919



Posts: 1467
Joined: 12/17/2004
From: Martinsville, IN, USA
Status: offline 		When manufacturing a product most of the time it's a question of economics. When I buy bearings the cheapest is open , then metal seals , and then rubber seals. Sometimes quite a price spread. An engine maker has to make the same choice. If they have a close fitting hub the only advantage of an open bearing would be no friction from seal drag. There's one engine I never seem to read about bearing failure. That would be Super Tigre. They seem to use a little better quality bearing. Usally it's a planned obsolensence factor. Will the part last for average use past the warranty period. When I worked for RED WING SHOES we tested soles all the time for the perfect wear. NOT to fast and not to long. WE could make a sole that would last long after the leather fell apart. You would look at the sole and see hardly any wear and the bad leather upper and say what a crappy shoe. (even thou it might be 4 years used as every day work boots ) Sorry to ramble I'll bet engines like JETT and NELSON have better bearings.

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(in reply to DarZeelon)
       Post #: 34

RE: front bearing, zz or rs shield?? - 3/20/2006 1:21:57 AM   
loughbd


 

Posts: 2111
Joined: 11/29/2003
From: Bremerton, WA, USA
Status: offline 		I bet Dubb Jett uses the same bearings that most of the big manufacturers use. OS uses NTN and NSK bearings and if you do the minimum maintenance they will last for years. Saito uses NSK too. My Saito 45 bearings lasted 24 years before they needed replacing. Don't know how many gallons of fuel I've run through that little engine.US companies used to use Fafnir. I have use SFk bearings with good luck. All my japanese engines came with single shielded bearing in the fron and open in the rear.

(in reply to speedster 1919)
       Post #: 35

RE: front bearing, zz or rs shield?? - 3/20/2006 5:13:22 AM   
DarZeelon



Posts: 7108
Joined: 4/9/2003
From: Rosh-Ha'Ayin, ISRAEL
Status: offline
quote:

ORIGINAL: speedster 1919

....I'll bet engines like JETT and NELSON have better bearings.


Randy,


Yes, they do!

They are made by WIB of Swizerland and are also used by MVVS in their engines.



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MVVS - Jett - Nelson - Bolly - Mejzlik

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       Post #: 36

RE: front bearing, zz or rs shield?? - 3/20/2006 6:48:59 AM   
Piet Le Roux



Posts: 156
Joined: 4/22/2005
From: BloemfonteinFree State, SOUTH AFRICA
Status: offline 		I had an ASP 52 and that also had a rubber seal in front. The two OS motors I have have NSK bearings with a metal seals in front and the rest is open. I stay in a place that gets very dry and dusty in winter time and I don’t think a bearing will last very long when dirt get in it.

(in reply to asmund)
       Post #: 37

RE: front bearing, zz or rs shield?? - 3/20/2006 7:14:20 AM   
loughbd


 

Posts: 2111
Joined: 11/29/2003
From: Bremerton, WA, USA
Status: offline 		That's why the front bearing has a metal shield. To keep dirt out. That's why it's called a shield.

(in reply to Piet Le Roux)
       Post #: 38

RE: front bearing, zz or rs shield?? - 3/20/2006 2:34:00 PM