I need to save this burning motor

[Mishael]

Hi, all. I've got quite the predicament. In short, I have an arcade game in the "pusher" category (coins drop down, drop on a moving platform, platform pushes coins into a hopper and tickets are dispensed accordingly) and the motor that drives the 8 different pushers stopped working.
I've got a Parvalux motor running 115 VAC, .77 amps, 35 watts, 1700 RPM with a gearbox attached that takes it down to 20 RPM, which powers the pushers. Until tonight, the motor wouldn't even rotate. I took it apart and cleaned it, and it turns now but it runs for about 30 minutes before getting hot enough to burn my hand.

Into the weird parts:
-run and start windings have the same resistance; each are in the 30-some Ω range
-the resistance readings add up properly and none have contact with ground (it starts and runs alright, after all)
-the gearbox lubrication is what i would describe as golden-brown, dried caulk but the armature still turns the shaft smoothly and quietly. there is one bearing that is noisy and could be replaced but that is not a concern at this point.
-the 10 μF capacitor is wired with one lead on the run winding, one on the start winding, and thats what the diagram printed on it says as well
-the power into the motor wired as the game is supposed to run it has a connector with hot run to the common, and neutral run to only one winding, leaving the other winding not having power

ideas? a new motor is $895 and is not a viable option

 

[shortbus=]

Have a look on the Grainger web site, they may have a motor that can be adapted. They have a lot of different types of motors, so it may take some looking to find what you need. https://www.grainger.com/Grainger/d.../ecatalog/N-9ww?Ndr=basedimid10071&sst=subset

 

[alec_t]

there is one bearing that is noisy and could be replaced but that is not a concern at this point.

If it's noisy there is excess friction. That will cause heating which, if sufficient, could result in metal expansion enough to cause increased friction or even bearing seizure, which in turn will cause more heating.......

 

[Mishael]

I had already been looking over the Grainger options and nothing really seems to be able to fit my need/budget relationship, plus I really don't have much to work with when it comes to adapting something because of the space where the motor is installed, and on top of that I can't actually find one that my superiors would be satisfied with. It needs specific torque and RPM
I ruled out the bearing being the sole cause of the overheating because it doesn't actually have much friction. When I get home tonight I am going to lubricate it with a few drops of oil and see where I get but I'm not holding my breath on that solving anything

 

[pfofit]

Show the diagram.
Is it a start or run cap?

 

[Mishael]

its a start cap, ill work up a diagram for it

 

[Mishael]

View attachment 69098

 

[panic mode]

what is the rated duty cycle of that motor? are the gears of bearings worn out? small gearmotors like this should not cost $900, more like $100-300.
Oriental motor has big selection, but they are pricey. here are some 40W models:
https://catalog.orientalmotor.com/r...9&prodid=3001139&action=&forward=&backtoname=

if you can live with lower speed such as 18RPM, you can get one for $160:
https://catalog.orientalmotor.com/i...&by=prod&filter=0&categid=1056&prodid=3001023

also check the specs, for example temperature rise (your motor may be just fine)

 

[cowboybob]

Couple of years ago I restored a basket case 1946 Seeburg jukebox.

The 64 yr old motor in it, not unlike the one you describe and which ran everything, got extremely hot even though the RPMs were OK.

ALL the problems ceased when I oiled (with 10W40) the motor and all shaft bearings. Mutiple times. Even if the motor only has bushings the oil will, in time, get into them and help.

And the gear box definitely needs to be cleaned out, run with a light oil for while (to get into and clean the bearings/bushings), then cleaned again and re-stuffed with a heavy gearbox grease.

Only reason I suggest this is that you said you cleaned the motor but made no mention of oiling it and, apparentely, did nothimg with the gearbox.

As an aside, my family (in the 50's) vacationed at Crystal Lake (Pilgrim) in the summers. Absolutely LOVED it. Sleepying Bear dunes with the stripped Cadillac dune buggies, etc.

 

[Mishael]

Did i mention that this motor was made in the UK by Parvalux? Its expensive because it is. I found out that my distributor had a 80% markup on their price, and direct from the Parvalux US branch I can get the motor/GB for $550, the motor only for $465 which is much more reasonable.
SINCE MY FIRST POST, i obtained some very interesting information.

-Year of manufacture: 2002
-Start to run winding resistance rated: 70Ω (why in the hell is mine 74Ω?)
-Motor amp draw measured: .71 amps no load (.77 rated)
-Shaft diameter: 12mm (which means 1/2" shafts are no good, 12mm=.47")
-Gearbox condition: Full of mostly worn grease, some now more like rubber-in the process of removing it, but i cant get any of the bearings off so I dont know how to clean most of the garbage off of the gears in the back of the box. The Parvalux rep recommended axle grease
-Capacitor tests out fine
-under load, the motor will pop its thermal overload after a half day of running, consistently. it does this every day (forgot to mention that earlier)
-current motor has a torque rating of 8.18 Newton Meters, or 72 inch-lbs

I dont understand a lot of things about this.
-Why does it pull less than the rated amperage but still heat up so quickly?
-What is causing all of this excess heat if everything is in a normal operating expectation?
-How would the windings increase in resistance...?

 

[alec_t]

Why does it pull less than the rated amperage

Because the winding resistance is higher.

What is causing all of this excess heat

Probably friction because of the noisy bearing and gearbox gunge.

How would the windings increase in resistance...?

They haven't; it's just manufacturing tolerance and entirely in line with the reduced current draw.

 

[dr pepper]

I remember those, they were great.

Try running the motor disconnected from the gearbox, just on its own and see if its gets hot still, if its doesnt then you can suspect the box or the machine.

If you have access or can borrow, do an insulation test at 250v using a megger, old motors like that can sometimes have degraded insulation and shorted turns, and can leak to earth, at the very least you need to see if its safe, 2mohm is the min, but I'd like to see an infinite reading.

You can if your carefull and really patient rewind motors like that, a friendly rewind shop can supply you with wire and sheets of insualtion material.

 

[Mishael]

I can't get the motor apart from the gearbox...but i reinstalled it into the game because I did everything i could to it. One of my bearings was pretty bad but i put a few drips of oil on it and it spun like there was no tomorrow.

I know it has no leak to ground and I am completely sure of that, and I know the windings are not shorted between another

Also, there are no motor shops within 50 miles of me. My part of Michigan is great for weed, education, and banking, but thats about it.

 

[dr pepper]

Well if you got it working thats ok then.

I have several rewind shops, a major electronic component distributor and a couple of engineers merchants within a few miles of my place.

But no weed.

 

[Mishael]

It hasn't overheated yet, which is fantastic. I realized the heat issue was that this motor is in an area that has 8 large ballasts about 18" above it mounted on wood boards, plexiglass sheets on all 8 sides about 10" away, and it has a 4" diameter hole directly beneath it, being the only opening to other air. There is no air movement and on top of all of this, there are about a dozen halogen lights, a dozen tiny fluorescent lights, 10 separate motors different from the one that was overheating, a computer roughly the size of your television, and a power supply that seems to be large enough to deal with your house. I'm throwing a pancake fan directly on the motor and I'm going to most likely install 2-3 more fans on the top and bottom then figure a way to get more air inside the motor compartment. This game gets very hot inside.

I really appreciate the support and answers