Motor armature free to drop down at least an inch too low.

[AlexM]

My Homelite corded electric mower overheated and shorted out the bridge rectifier, which I replaced to get the motor working again, but the armature (if I'm using that term correctly) is free to drop at least an inch lower than where it should be, causing the bottom to rub against the mower body as the blades turn. I can move the armature up and down at least an inch by pushing or pulling on the mower blades underneath, and I can push it up to within around half an inch of where it should probably be, but not high enough to keep it from rubbing. The only obvious damage I can see are two metal "tabs" near the top of the armature that are melted away. In the attached photos, the melted tabs are steel-colored and roughly in the centers of two of the photos, framed by white plastic on the left and right. In the first photo, it's right under the blue wire and the center of the motor. In the third photo, I had pulled the blades and armature down, and you can see the bottom of the armature from underneath the mower.

Were those two "tabs" holding the armature up? (It seems strange, but I can't think of what else might be wrong.)
What are they called?
Is there a way I could fix this for much less than the cost of a new motor? (Makeshift is okay, but I don't have welding equipment.)

 

[sgkent]

my 2 cents - all the electric appliances I have repaired over the years cost me as much in parts as it did to buy a new one. Usually the whole motor should be replaced when it suffers a meltdown. You can have one shorted winding that you can't see, and go thru the whole thing again. Unless you can get the melted plastic parts for $25 or something like that and roll the dice, usually by the time you find new parts, it isn't worth the trouble - at least that is what I have found. I started with EV things, corded and battery 30 years ago and tossed all of them for ICE things because when something like what has happened to you happened, the parts weren't available or designed for replacement.

I might add, one of the techs here posted a thread not long ago how if you overload an ICE mower it will slow, stop or even shear a flywheel or blade key if too fast, even a crankshaft can be bent. But if an EV is overloaded or stops too fast like a root etc., the damage to the electric system is instantaneous.

 

[AlexM]

my 2 cents - all the electric appliances I have repaired over the years cost me as much in parts as it did to buy a new one. Usually the whole motor should be replaced when it suffers a meltdown. You can have one shorted winding that you can't see, and go thru the whole thing again. Unless you can get the melted plastic parts for $25 or something like that and roll the dice, usually by the time you find new parts, it isn't worth the trouble - at least that is what I have found. I started with EV things, corded and battery 30 years ago and tossed all of them for ICE things because when something like what has happened to you happened, the parts weren't available or designed for replacement.

Thank you, sgkent. i definitely won't invest much in trying to fix this, but the two little metal tabs that melted seem as if they might be replaced or replicated at minimal expense with a bit of luck--if they're the problem. Other than its low position, the motor seems to run just fine.

 

[bertsmobile1]

Cheap & nasty electric houshold gear do not have any bushes or bearings and have the armature spinning against the plastic body.
When they get too hot the plastic softens and the holes flog out
In some cases you can modify them to take an oilite type self lubricating bush , like you have in a starter motor .
However the down side is some times this causes parts to become electrically live so you need to be a little careful .
I have some B & D shredders that are now 40 years old .
I keep them because they chop up light garden waste very very fine so it almost explodes when I compost it .
When I fist got them I had the motor replaced twice under warranty because it ran for so long the plastic soften and the armature moved sideways causing an internal short circuit and in one case making the whole machine live , not good in the garden .
Solution was to connect a timmer to the power cord to limit the run time to under 45 minutes .
I have 3 flymows in the workshop that have done the same thing, they are being kept for parts.
Electric mowers are a big problem if the owners allow the grass to grow too long.
This loads up the motor so it runs slower
Running slower has the high amps running through the individual winding for longer than the engie was designed for and they start to overheat , which raises the resistance which generates even more heat in a self feeding loop

 

[AlexM]

I'm guessing my questions were too specific. Much more generally, what holds the armature up in an electric mower motor?

 

[StarTech]

Usually it is a spacer between the bearing which sits in the housing end caps. In your case what it was is melted as is shown in your images. In the last it look the housing end has failed itself. Motor is now scrap metal as most replacement parts are not available.

As SGKent said they are not worth the trouble any more as replacements are usually just as cheap as one or more replacement parts if they are even found. It is like replacement lawn mower starters OEM starter parts are often not available and if even available cost more than a complete replacement after market starter.

Here is an example repair job last week, Customer needed a solenoid for his solenoid shift starter on a Kawasaki. My cost of a 27010-7005 is $135.02 plus $15 shipping. But a complete DB starter was only $84.19 including shipping. So I sold starter for $135.00 and if the customer had gotten a new Kawasaki starter it would had been 4235.02 for and cost me $177.25 plus $15 shipping.

So the customer got a good deal, I got a good deal, and we both are happy; John Deere is not because their starter was $198.49 cost and the solenoid itself was $208.64 cost; therefore they lost the sale.

 

[sgkent]

Alex, put the model and serial number down, all the pertinent information so if there at least someone can Google it to see if any parts come up. There are a million different motor designs in the world, and until that mower is apart you won't know exactly what is wrong. But based on my experiences with other electrically driven yard equipment that I have owned, they are not impressive in how they are engineered, and not generally designed for repair. If they are reasonably new sometimes parts are available. Usually if they fail under warranty, the manufacturer just gives the owner a new one.

 

[AlexM]

Usually it is a spacer between the bearing which sits in the housing end caps. In your case what it was is melted as is shown in your images. In the last it look the housing end has failed itself. Motor is now scrap metal as most replacement parts are not available.

As SGKent said they are not worth the trouble any more as replacements are usually just as cheap as one or more replacement parts if they are even found. It is like replacement lawn mower starters OEM starter parts are often not available and if even available cost more than a complete replacement after market starter.

Here is an example repair job last week, Customer needed a solenoid for his solenoid shift starter on a Kawasaki. My cost of a 27010-7005 is $135.02 plus $15 shipping. But a complete DB starter was only $84.19 including shipping. So I sold starter for $135.00 and if the customer had gotten a new Kawasaki starter it would had been 4235.02 for and cost me $177.25 plus $15 shipping.

So the customer got a good deal, I got a good deal, and we both are happy; John Deere is not because their starter was $198.49 cost and the solenoid itself was $208.64 cost; therefore they lost the sale.

Thank you, StarTech.

What did those two tabs that melted on my mower attach to in order to hold the armature up? I'm thinking I might be able to fabricate something, as parts for this mower are no longer available. A new motor, if I could find one, would cost almost as much as a whole new mower, so I'm trying to find a way, however funky, to save this one.

When you say the bottom housing end has failed, it looks to me as if there never was one, which seems strange, or the whole thing somehow disappeared, which seems even stranger. Do you have any theory about how what you're seeing could come about?

 

[AlexM]

Alex, put the model and serial number down, all the pertinent information so if there at least someone can Google it to see if any parts come up. There are a million different motor designs in the world, and until that mower is apart you won't know exactly what is wrong. But based on my experiences with other electrically driven yard equipment that I have owned, they are not impressive in how they are engineered, and not generally designed for repair. If they are reasonably new sometimes parts are available. Usually if they fail under warranty, the manufacturer just gives the owner a new one.

Thank you, sgkent. It's a Homelite UT13120, for which I've searched pretty thoroughly for parts, all of which are discontinued and out of stock. If I can just find some way to hold the armature up, it should work well. First, I have to figure out exactly how it was held up originally.

 

[bertsmobile1]

Good chance what ever held it up has mented or broken off
Usually it is nothing more than a boss cast into the end cover .
There is not much axial load on the rotor when the motor is running as the magnetic fields will tend to centralize the armature inside the field windings / magnets
What pulls the armature down is the action on the blades which trys to suck the air ( and grass) up so of course pulls down with equal force .