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Re: [Amps] Resistors

To: Colin Lamb <k7fm@teleport.com>
Subject: Re: [Amps] Resistors
From: David Kirkby <david.kirkby@onetel.net>
Date: Mon, 25 Apr 2005 22:42:44 +0100
List-post: <mailto:amps@contesting.com>
Colin Lamb wrote:
> I used to want ball bearing fan motors for computers.  However, even though 
> they may have a longer period without service, they can become noisy.  

Ball bearning fans are generally noiser than sleve bearings - at least 
that was what I found when I looked at replacing the fan on the DC-DC 
converter some time back on my Sun.

That was a real pain, as it was something like 60x60x15mm. I could only 
find one fan of that thickness (it might have been 10mm in fact), so had 
no choice in the matter.

> I have found that the sleeve bearing fans can be oiled quite easily and 
> continue for a long time.  The sleeve bearing depends upon lubrication.  In 
> effect, the bearing is the oil itself.  Without oil, there is no bearing.  
> Annual lubrication by removing the label and plug covering the bearing can 
> keep the bearing going for a long time.  I can often bring a seized bearing 
> back to life with a removal of the bearing and cleaning of the burned residue 
> and relubrication.  

Papst do some sleve bearing fans that they claim have lives comparable 
to balls. They say, as you do the lubrication is important, but these 
ones are supposed to trap the lubricant in some way (can't recall 
details, but I think it was Papst who had it).

Personally, although I know all about the bathtub curve and infant 
mortaility rate, I would rather keep clear of cheap PC fans.

> A few years ago, I came upon a small hydroelectric power plant undergoing 
> annual maintenance.  The generator used sleeve bearings.  I asked the fellow 
> how long the sleeve bearings lasted at 24/7.  His answer was "about 30 
> years".  

But clearly they were designed to a higher spec than your average PC fan.

> But they regularly lubricate them.  I no longer make slanderous comments 
> about sleeve bearings.  
> 
> 73,  Colin  K7FM



-- 
Dr. David Kirkby,
G8WRB

Please check out http://www.g8wrb.org/
of if you live in Essex http://www.southminster-branch-line.org.uk/


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