The fans I've seen, the bolt comes in from the side, and
presses on the flat side of the shaft.

Yes, sometimes they do loosen up. Happens with pulleys,
also. The bolts loosen up and the pulley falls off. I saw
that a couple weeks ago, one of the furnace at my church had
the pulley fall off.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"Jules Richardson" wrote
in message ...
On Mon, 03 Jan 2011 20:47:48 -0800, Molly Brown wrote:

Any centrifugal fan that is secured to the fan motor shaft
with only one
bolt will eventually become loose and begin to hit the fan
cage.

Surely any fan with just one bolt will have the threads cut
in the
opposite direction to the motor's rotation, so that the
motor's turning
will have a tendency to tighten the bolt rather than loosen
it? Or have
you seen designs where this isn't the case?

cheers

Jules