Split phase motor question

Even if I didn't know at least one other group that you frequent, I'd STILL suggest that you ask over on r.c.m -- this group tends to be best for asking why your 555 doesn't work so that we can give you the 3rd degree to find out that you're using a 10 megohm resistor in the discharge path, or why your drive transistor always blows out after one use, so that we can find out you're not using a snubber.

Yes, a loose winding is a believable theory, but I'm just nodding my head at your guess, not adding anything valuable of my own.

I've seen some with a centrifugal switch inside, dunno if for speed regulation or for start/run

Yeah I've got an oldie that runs a little bench grinder. It's got said centrifugal switch inside. I can hear it click in when it comes up to speed.

George H.

This motor does indeed have a centrifugal switch inside. I thought about out of balance but the noise stops as soon as power is removed. If spun up with a drill motor it does not make the noise. Only when powerd up does it exhibit this behavior. Eric

when you turn the power off the motor doesn't get faster so the switch won't cycle. can you do a speed measurement, does it click while speedinng up, or only at full speed?

Long-term overheating can make brittle the plastic insulating lining between copper and steel, allowing the windings to move slightly. If it is winding movement, it would sound like 60Hz buzz. If its possible to lock the rotor, this noise would occur without rotor movement. A loose winding like this can short to the core and be a possible shock hazard. Scott

It is not the centrifugal switch, it operates normally. It clicks once wehn the motor is nearly up to speed and then again when the motor has slowed down to about 50% speed. The sound it makes is a knocking sound, like someone was pulling and pushing on the shaft so that it hits the thrust bearings at either end. But the shaft isn't moving back and forth. Maybe I can look at the sound with a 'scope and determine the frequency. Eric

Greetings Scott, This motor is about 80 years old. There is no plastic inside. It does have two bakelite knobs on the outside that screw onto the wire terminals. Eric

The old motor I have does rattle back and forth some times... but it is the shaft moving. I switch power on and off and that will usually stop it. It won't get up to speed in the rattle mode. Hey maybe we have the same motor? (I'll try and remember to go get a part number off it.)

These motors are pretty simple in construction. Why not take it apart and see if you can locate a loose centrifugal switch part or such?

d.

I have had it apart to clean and oil it. It is not the centrifugal switch. It is not the rotor causing the shaft to bang back and forth against the thrust bearings. I am, frankly, mystified. That's why I posted here for help. I think I really need to hook up a mike to my 'scope and check the frequency. If it is 60 cycles then it most likely is caused, I think, by changing magnetic fields. It may also be caused by the pulsating nature of the single phase power making the motor speed also pulsate at 60 cycles, but I don't think so. Eric

The switch kicks out when the motor starts running, well before reaching full speed. Another method uses a potential relay and a starting capacitor.

I just had to rebuild a dual capacitor pump control for my well. Then the 22 year old pump quit pumping water even though the motor is running. A clamp on ammeter shows the right current on each of the three leads. Now, I get to pull the pump of of the 80' casing to put in a new pump. Of course, I've found no one to help lift it.

The above ground pump on my dad's well failed. The well driller refused to repair it, and charged him $3800 to drill a new well because it was over 10 years old.

It would use 'Fish Paper' to insulate the windings from the laminations.

This is what I have. (Well almost I have style 2452171)

There is a certain beauty that new motors lack.

George H.

Sounds like you are saying you know what is wrong. The shaft moving back and forth along it's axis?

Then you either need to limit the travel of the shaft, or fix whatever is wrong with the load causing the shaft to move.

Thrust bearings? Often as not a thin metal washer, the bearings are there mostly to deal with radial loading.

Is the rotor balanced?

Sink a couple of posts and put a beam across, then use a come-along (ratchet lever cable hoist) or block and tackle.

I lifted a big fiberglass boat and motor off a trailer using four posts, just so I could repair the trailer. (I cheated and lifted the boat and motor with hydraulic jacks then tied the boat and motor off with 1/2" ropes and lowered the trailer and pushed it out)

Considering the problem was the pump and not the well why did your OM go for it? Sand being sucked up into the pump? 10 years old is nothing, my above ground pump (driving a deep well inductor type thingee) has been in service for 30 years that I know of.

I was planning on a tripod made from three 16' 2x4s, and my chain hoist. Much safer than a come along, when you only have one good hand. :)

The problem right now is it's too hot to work during the day, and you have to be careful about disease carrying mosquitoes in the mornings and evenings. I'll have to keep hauling water for now. :(

They simply refused to work on it, and he won't admit it but he can barely walk due to a bad hip. I offered to repair it, but he's become a pushover in his senior years. They convinced him that the piping and hardware inside the casing was bad, instead of the old pump.