Fan Motor Bearing

[hammermill]

when my son was a wee tadpole i received a old junk cash register from the dump. in the next couple of months he learned a lot as it was disassembled to basic parts.

[scmods]

When my son was growing up, I would hand him a part and ask him to speculate as to what was going on. I, of course, knew what the ultimate failure was, but felt that a forensic examination of selected components was important to his understanding of mechanical interactions between components. The idea was to give him exposure to as many different types of surface conditions and underlying causes as possible. I have always tried to autopsy as many of the failures I have been called upon to remedy as possible, just to learn what was going on, and what the wreckage would tell me, and I wished to convey the interest and ability to him.

It seems that kids today have less opportunity to be exposed to how things actually work than my generation, and the best and brightest are channeled into a college-bound school program, while the skilled crafts are relegated to the vocational school ding dongs. I shudder to think where this is going to lead.

Bill Walck

[tornitore45]

Often the higher learning received in college is pitted against the practical experience gained via a trade and hands on labor.
These two seemingly opposite way of learning are not incompatible, there is noting preventing to acquire knowledge and experience throug both method. Is rare a person lucky enough to learn manual and observational ability by practice and acquire theoretical knowlege to support guide and validate what is learned experimentally.
In past centuries all great minds were experimenter, thinkers and scolar all wrapped up in one person. Is only recent history that segregated society in sutes and blue collars just to use two classist espressions I do not particularly like.
Far from being a great mind, my experience came from both fields, eperiences in "the sop-lab" reinforced and clarified the learning in the classrom.

I shudder to think where this is going to lead.

To loosing the technological edge we have enjoyed for a long time.
I see many new college graduates reciting book knowledge like parrokeets but having no clue of the deep meaning of things.
Getting a practical experience on the job is becoming more and more difficult, employes want to get instant results the bid for the small pool of experts rather then developing skilled technicians.

[whateg0]

I'm lucky in that my son loves to take things apart and figure out how they work, then put them back together. He's 9. It's such a joy and it's fascinating to see that he really understands mechanisms so well. We once stood by an antique clock taken from a clock tower somewhere for close to 20 minutes while he walked around it figuring out which way each shaft turned and what it did. Then he explained it all, starting with the pendulum and escape wheel. He's also a bit of a perfectionist, so after disassembling an old office phone that was bound for the trash, he put it back together only to find that he put each button upside down. So, he took it all back apart and flipped them over before reassembling it.

Back to fan motors, there is one sitting on my bench that I had hoped to salvage, because I really do like the look of the fan. Unfortunately, a couple of years ago, it started to slow down, so I took it apart, cleaned it up and put some lightweight oil in the bearing/bushings. It ran much better for a bit, but as others have said, its life was shortened. The next time it happened, I wasn't there and one of the bearings seized, causing the motor to get hot and cook itself. It sat collecting dust, until I could confirm that it was really the motor itself that was bad. So, now most of it sits on my bench waiting for disposal, I suppose. I did salvage the guard and blades, though and made an adapter to put it on an old HF drill press motor and it now keeps me cool while I crank the handles on the mill. I do wish I could find a suitable motor to make it look like it did before.

Dave

[Ganesh1199]

Nice Thread...

[John Hasler]

Bill Walck writes:

A popular motor design in the past for table fans and other low-powered applications was the shaded pole. This is what is shown in the electromagnet application photo. With DC, there is no fluctuating magnetic field to induce a counter EMF in the heavy wire, so its removal is operationally unnecessary. In it's original application, however, the fluctuating field of the AC powered coil induces a current in the heavy wire coil. This current creates it's own magnetic field which weakens the overall field in one part of the pole and causes the rotor to turn. If not particularly powerful or efficient, it is a simple and durable power source, and it is self-starting. The newer fans all seem to be multi-speed, and I am at a loss to see how multi-speed could be accomplished in a shaded pole design without losing the simplicity that is it's strong point.

They simply have tapped stators and run at very high slip. This works well for fans because the torque is roughly proportional to the square of the speed.