A sleeve bearing is a ring or collar that surrounds the shaft.  The sleeve
is made of a softer metal (typically a bronze alloy) which wears away
while protecting the shaft.  As the bronze sleeve wears away (from the
inside) the shaft eventually can wobble in the enlarged inner diameter,
which we hear as the whirring/buzzing noise.  Back in the days before we
became a disposable society, the sleeve bearing was (and still is) the
cheapest to produce AND repair.   Repairing a CPU fan isn't practical but
there are many products that still use this type of bearing.  The beater
bar of a vacuum cleaner is one example.   For something that large, it is
a relatively simple task to pop out the old sleeve and insert a new one.
But in today's society, it is easier and (unfortunately) cheaper to toss
out the whole unit and buy a new one.

A roller bearing, as the name implies, uses small cylinders (rods) which
rotate in one direction only.  Sometimes these bearings are referred to as
pin bearings or rod bearings because the bearing is a metal cylinder.

A ball bearing, as many people have previously said uses tiny balls as the
bearing and is the best design of all.
Jim Meagher
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----- Original Message -----
From: David Gillett <[log in to unmask]>

> On 1 Jun 99, at 10:48, Roberto Safora wrote:
>
> > 1- What is the main difference between sleeve and ball bearing fans?
>
>   Sleeve bearings are little rollers -- they only turn on one axis.

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