Electric motor struggles to start up

May 19, 2010 17 Replies

Hi,



Is there anything I can do to get the electric motor for my favorite desktop fan to start up properly again?



When I turn on the fan, the motor axle/propeller try to rotate (while the motor hums), but if they do, it's usually only very slowly and for just a few moments before they stall completely. However, I can usually get the propeller rotating steadily at full speed by quickly rotating it by hand several times right after I switch on the fan.



Thanks in advance for your replies, Darro


how are the bearings? Does it turn freely? use sewing machine oil for lubrication. use wd40 if you want to ruin it.

are the brushes and commutator visible? signs of wear?

If it's a cheap POS, you should just replace it.

Try blowing out the motor with a can of air. Perhaps there is dust/lint, etc. in the housing.

I've found to dissemble, clean (brake cleaner spray works nicely). Relube with zoom spout turbine oil.

Oils such as sewing machine, three in one, or WD-40 tend to dry up and stop working in a few weeks or months.

99.9999% sure it has no commutator or brushes. Because about 99.99999% of fans don't (except blower motors in automotive heating and airconditioning systems - which are technically blowers, not fans.)

If automobiles had an AC system instead of DC, then they too would have no commutator or brushes. But they don't. So they do.

Well, depends on duty cycle... somewhere around a year IME, though. Buys you time to source a replacement, but that's pretty much it.

cheers

Jules

On 5/19/2010 7:31 PM Tony spake thus:

Where do you get "automobiles" from any of this? The other person said

*except* automotive heating & AC.

OP described the motor as belonging to a "desktop" fan. Therefore a common garden-variety induction motor, therefore no brushes. Sheesh.

On 5/20/2010 5:36 AM Jules Richardson spake thus:

Why replacement? If it starts slowing down again, just shoot some more oil in them bearings.

My guess is it'll last a lot longer than the nay-sayers here say it will. I've done this many times--rescue sluggish motors by lubricating them--and usually they for for *years* before needing attention.

And a great number of "DC" motors don't have brushes either. But they are on higher end equipment than car blower fans.

The 1958 SeaBreeze fan I "resurrected" about 6 years ago with SM oil is still going strong.

Sheesh yourself, what is the big deal? I was commenting on why the blower fans in autos have brushes.

On 5/20/2010 4:08 PM Tony spake thus:

OK; I guess my trigger's been set pretty low lately, as there seems to be more than the usual Usenet bullshit flying around.

About this time off the year I take most of my fans apart, then clean and oil the shafts. I have a couple of fans that are over 25 years old still going strong. A few of them are the small cheap clip on ones.

I'll get over it. OK, I'm over it.

Just an update to my inquiry....

After lubricating the motor shaft with sewing machine oil, my favorite fan works perfectly again. I intend to do this every so often to keep it running for as long as possible. A big thank-you to everyone who took the time to help me get my fan going again.

Cheers, Darro

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