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GE BMY Centrifugal Start sound?


Kyle Koser
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So I'm working on my 12" GE BMY with centrifugal start switch, and got it wired up tonight. This is the first time I've heard one, and I have no idea if it sounds normal or not. Pretty clunky on initial start up, and once the centrifugal switch disengages its quiet. Also, on Medium and Low the fan does not spin fast enough for the centrifugal switch to disengage. If I start it on Hi and let it reach maximum speed, I can switch it to Medium or Low and the switch stays disengaged. Although eventually if I let it run on low long enough the fan starts to slow down and the centrifugal switch engages and makes a bunch of racket.

I still need to clean up the brass, install the oilers, and put some finishing touches on it, but I couldn't help but see the thing run. Interesting modification by a previous owner by drilling and tapping a screw for the bearings, but I think I'll like this fan.

BMY Startup

 

 

BMYStart.jpg

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It seems like the start switch is taking longer than it should to disengage. Mine makes a similar noise, but starts very quickly.

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12 hours ago, Russ Huber said:

That is an early bugger. Are those replacement springs on your centrifugal mechanism? 

 

 

No idea on the springs, but it makes sense! I suspect the same individual who added the bearing screws also could have changed the springs.

2 hours ago, Tom Morel said:

It seems like the start switch is taking longer than it should to disengage. Mine makes a similar noise, but starts very quickly.

Thanks for the reply, it does seem to take longer than it should to disengage. Hopefully I can find some different springs to try.

 

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I would look into a rotor binding possibility. Does the blade spin fairly free with the power off and a flick of your finger? And what is up with those bearing screw additions? Are the bearings worn? Things to look into. 

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13 minutes ago, Russ Huber said:

I would look into a rotor binding possibility. Does the blade spin fairly free with the power off and a flick of your finger? And what is up with those bearing screw additions? Are the bearings worn? Things to look into. 

Blade spins freely, with the exception of the centrifugal starter dragging on the armature. I was actually very surprised how smooth the rotor turned the first time. Bearings don't look worn to me. The bearing screws thread through the motor housing into a drilled and threaded hole in the bearing. 🤷‍♂️

I looked at your other thread comparing centrifugal switches and found a photo of Anthony Lindsey's fan. Springs look different and not as stout as mine.

 

AnthonyLindseyBMY.jpg

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If I remember right, Those are floating bearings and self align. Make sure those screws aren't interfering with them. 

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On 2/11/2024 at 1:21 PM, Kyle Koser said:

Blade spins freely, with the exception of the centrifugal starter dragging on the armature. I was actually very surprised how smooth the rotor turned the first time. Bearings don't look worn to me. The bearing screws thread through the motor housing into a drilled and threaded hole in the bearing. 🤷‍♂️

I looked at your other thread comparing centrifugal switches and found a photo of Anthony Lindsey's fan. Springs look different and not as stout as mine

Hi Kyle. That is a beautiful fan you have there. I need to preface my message by saying I don't own one of these fans; but I do work on a large variety of electric motors. 

It sounds, to me, as if the centrifugal switch is disengaging the start winding before the motor is up to a sufficient speed. You notice there is rapid acceleration for a second or so, then as soon as the centrifugal switch turns off, the speed seems to "hang" for a period of time before continuing to reach full speed. That could mean that the centrifugal switch springs are not quite providing enough tension to hold the start circuit in effect until the correct speed. 

The problem with Low not providing enough speed to keep the centrifugal switch disengaged seems to contradict the above. This makes me wonder if a previous repair was made to the centrifugal switch, in an attempt to allow it to stay disengaged even when on Low; in spite of Low being abnormally slow for some reason.

You mentioned bearing screws and another discussion about the bearings. I looked and can't find that post but it would possibly offer more clues. There is likely something adding drag to the motor, mechanically, and restricting the speed. Unless modifications are made, motors from this era typically run too fast on Medium and Low due to the higher voltages in use now. 

The bearing modification and the other indications of repairs make me think someone has been fighting this problem for a while now! 

 

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On 2/14/2024 at 6:19 AM, Kim Frank said:

If I remember right, Those are floating bearings and self align. Make sure those screws aren't interfering with them. 

Correct, these are a self aligning/floating bearing. I removed the "set screws" but the front bearing easily slides in and out with the rotor shaft. I guess my bearings are worn more than I thought? 

On 2/14/2024 at 8:52 AM, David Allen said:

Hi Kyle. That is a beautiful fan you have there. I need to preface my message by saying I don't own one of these fans; but I do work on a large variety of electric motors. 

It sounds, to me, as if the centrifugal switch is disengaging the start winding before the motor is up to a sufficient speed. You notice there is rapid acceleration for a second or so, then as soon as the centrifugal switch turns off, the speed seems to "hang" for a period of time before continuing to reach full speed. That could mean that the centrifugal switch springs are not quite providing enough tension to hold the start circuit in effect until the correct speed. 

The problem with Low not providing enough speed to keep the centrifugal switch disengaged seems to contradict the above. This makes me wonder if a previous repair was made to the centrifugal switch, in an attempt to allow it to stay disengaged even when on Low; in spite of Low being abnormally slow for some reason.

You mentioned bearing screws and another discussion about the bearings. I looked and can't find that post but it would possibly offer more clues. There is likely something adding drag to the motor, mechanically, and restricting the speed. Unless modifications are made, motors from this era typically run too fast on Medium and Low due to the higher voltages in use now. 

The bearing modification and the other indications of repairs make me think someone has been fighting this problem for a while now! 

 

Good information, this thinking is opposite of what I was thinking! However, your explanation makes sense in regards to the speeds and voltages. 

 

As for now, I'm going to play with the set screws, and find the optimum positioning to allow the fan to run. I ran it without the set screws and all 3 speeds worked properly and fan stayed on low speed with out issues. 

 

Thanks to everyone for the reply's and ideas! I will be sure to post again when the fan is complete. 

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