Comments on: Dissection of a Furnace Fan Motor

By: James

James — Fri, 09 Dec 2011 01:49:07 +0000

“Daestrom” is a well known troll who has been polluting engineering forums for as long as I’ve haunted the usenet. Arguing with that sort is a fool’s errand, they’re best ignored.

By: Pete

Pete — Sun, 23 Oct 2011 23:11:45 +0000

Another great article. I looked up your name on the suggestion of someone on the subject of generator backfeed and the “poor linemen” and I uncovered a mess of information and this site. Glad I did.

By: neonjohn

neonjohn — Wed, 19 Oct 2011 00:06:55 +0000

Hi Rudy,
The sad fact is that in most cases you can’t replace the bearing because no one stocks the replacement bearings anymore. Off-shore manufactured motors are so cheap that even if it only took 30 minutes to change the bearing, it would still be cheaper to scrap the motor and install a new one. Oh well.

At the shop where I moonlight some, they quit replacing bearings some 20 years ago. However I think there may be some old stock laying around. It’s like that in many shops. So just in case you can find the bearing, here’s how to change it.
1. Remove the case bolts and open up the motor.
2. Examine the shaft where the bearing contacts the shaft. If it is worn there then the motor is irreparable.
3. On the end-bell you’ll find another little housing, usually on the outside but sometimes not. It is held in place with 4 rivets. That’s where the bearing and oil retaining felt is.
4. Drill out the rivets or brads and open the housing.
5. You’ll see the bearing sitting there on some steel fingers that hold it in place while letting it rotate a little.
6. Replace the old with the new.
7. Saturate the felt with a good light machine oil such as 3-in-1 oil.
8. Put the housing back in place and either rivet or screw it in place.
9. Put the motor back together. You’re done.

John

By: Rudy

Rudy — Tue, 18 Oct 2011 15:59:18 +0000

How would you replace the sleeve bearing. Thanks

By: bill21842

bill21842 — Mon, 17 Jan 2011 20:36:36 +0000

Great article. Thank you for taking the time to do it and to make it available to the public. You do a great job with the photography too
BD

By: GEORGE mELTON

GEORGE mELTON — Sat, 03 Jan 2009 19:30:07 +0000

Glad to see your still the same old “Givem Hell” John we all know and love. Drop me a email some time and let me know how your doing…

By: dan

dan — Mon, 13 Oct 2008 16:07:51 +0000

Good Job John,

I too have had “fun” with some of these sites… A good deal of the instruction on the web, should really be call “destruction”… :>)

I’ve gotten into it with people tell others how to solder and desolder SMD devices, people using high gauge wire to hookup low current electronics (man yur not arc welding here) and a interesting delete and redact session on wikipedia regarding CFL lights, power factor, and that CFL lighting instruments are actually not even close to being a good and green replacement to incandescent light fixtures… oh don’t get me started… ;>)

Keep the faith brother!
Dan

By: Don Young

Don Young — Thu, 02 Oct 2008 02:19:05 +0000

Nice work, John. I knew that very small squirrel cage motor fans could be speed controlled; I have a 10″ Kenmore fan right here now that has a sliding contact resistor for speed control. I was not aware that furnace blower motors could. I was also not aware that the motors would overload if ran without back pressure until it happened to me! I believe in learning by experience.