Ball Bearings

These are some ball bearings taken from computer fans. Really, the term "ball bearing" is very misleading; it's much more accurate to call these "bearing assemblies", since each donut shaped unit has a number of round BB's sealed inside.

A "dual ball bearing fan" is a fan with two of these bearing assemblies supporting the fan shaft; a "single ball bearing fan" has one assembly.

Q. My fan says "ball bearing" on the label. Is that a single or double ball bearing?
A. It depends on the company, but it typically means a single ball bearing.

Q. My fan says "one ball, one sleeve bearing"; what does that that mean?
A. With most computer fans, "one ball, one sleeve" is just another name for a single ball bearing fan. Here's what it looks like on the inside:

Fan Hub Bearing

Peeling up the hub label reveals the fan shaft and the lock-washer that holds it in place. Removing the lock washer allows the impeller to be removed from the other side:

With the impeller removed, the hub bearing can now be seen clearly. In this case, it's a sleeve bearing. You can tell just by the color. Sleeve bearings are made of an alloy, and have a bronze or copper color. Hub Sleeve Bearing

Impeller Ball Bearing Turn the fan frame around so you're looking at the stator, and you can see the other bearing. This is the ball bearing.