Re: (ET) Pulling bearings on mower motors - Thank You Dean & Chris !

[Rod Hower <rodhower ameritech net>]

 If anybody has a drawing or part number for the brush springs I may be 
able to find a new replacement at work (Ametek-Bison, we manufacture a 
wide variety of PM brush motors).
    On Thursday, May 9, 2024 at 11:08:04 PM EDT, john <johnreinhard 
rochester rr com> wrote:  
 
 I completely dismantled an old spare deck today, to prepare to weld 
cracks, Re-make the inner blade surrounds, and sand blast & paint it all 
(Imron maybe ?).

It had only 2 motors on it, both need bearings.

I followed Deans recommendation and bought the bearing puller set.

Then I followed Chris' suggestions (including thread chaser to get max 
turns of socket head screw into shaft).

The hubs on both motors did not budge.

So, I wrapped a custom coil for my induction bolt heater around the hub, 
heated for about 60 seconds, and tried again.

It was still difficult, but I got it to move.  60 more seconds of 
heating & it came off. I used a large long screwdriver to prevent the 
puller from twisting as I turned the puller screw with a crescent 
wrench.  I should have used a socket & long breaker bar for the screw, 
but I am not sure how I could better hold the bearing puller setup to 
prevent turning.

Any suggestions ?

Similar process 2nd motor, except only took 60 seconds heating 1 time.

The bearing puller set worked better than a previous setup I had tried 
(similar style press plates, but 2 jaw puller instead of the Deans 
recommended setup): this time the blade end cap came off without cracking !

Following Chris' step 10, I did NOT use socket head screw, - but I 
SHOULD have (or something similar), because the puller damaged the end 
of the shaft, and I had to run chaser through again. The 2" bolt was too 
long for the bearing pull, so for the next motor, I will try a short 
bolt, or even a thick washer.

This was a non functional spare deck that had been sitting outside for 
years.  So the blade end bearing was seriously rusted.

I ended up using a chop saw (14" abrasive blade) to cut through outer 
race & pry it off. (Super careful - a slip would cut the windings or 
into the shaft)

Then I held the armature with one hand, and pulled saw carefully down, 
held a position, and moved armature back & forth to shave inner race 
until it was close to the shaft.

Nicked the shaft a tiny bit.

A couple taps with a cold chisel split the race, and it slid off easily 
with channel pliers.

Armature needed cleanup on wire wheel bench grinder.

for corrosion on end caps I used Dremel tool & 1" wire wheel - worked 
great.

Brushes were seized (corroded aluminum) but gentle taps with hammer & 
punch moved them, then scraped inside each rectangle brush holder with 
tiny slotted screwdriver & utility knife.

The brushes now go back in with firm finger push, but still drag too 
much for proper operation (spring push).

Again, any suggestions for a better method ?

SADLY, the brush springs had rusted & broken.

Anyone know where I can buy these ?

Bearing note: the small bearing was not very rusty, but did not turn. I 
put drops of oil at the shield groove & freed it up. The bearing did not 
feel 'BAD'.  I ran outer race against wire wheel bench grinder (NOISY 
!). EASY way to tell your bearings are not as good as you hoped !

I hope anyone else attempting this has less trouble than I have had.

I really appreciate the suggestions people have posted on this subject.

I welcome any more suggestions (especially brush spring #'s, sources, etc).

John


On 4/21/24 16:28, Christopher Zach via Elec-trak wrote:
> Ok, so I went out to the shed and pulled the bearings on an older fat 
> motor armature. Here are some thoughts:
>
> 1) The screw to take off the blade hub (hat) needs to be a 2 inch, 
> 7/16 thread socket head screw. ACE hardware stores have 1.5 inch steel 
> and 2 inch stainless. Get the 2 inch one.
>
> 2) When screwing it in you should be able to go 10 full turns. Note 
> that although the hole is threaded the blade bolts didn't really go in 
> far, so most of the thread in there is crapped. Might want to clear it 
> with a thread cutter, just don't break the thread cutter off in the 
> hole or that's probably that.
>
> 3) I went in 5 turns with my bolt before it got tough to turn on my 
> motor (another spare I had went in 10) which I figured was "good 
> enough". In my case it was.
>
> 4) The bearing puller set Dean posted is what I have, it's great, when 
> you hook it up to pull the hub remember not to tighten it so tight it 
> grips the shaft. Use the big puller for all work, there are reasons.
>
> 5) Put some grease on the head of the bolt so the puller can turn 
> easier against it. Wheel bearing grease is always nice to have.
>
> 6) Turn, wait, turn a bit more. Slow. It will eventually come.
>
> 7) Removing the bottom bearing from the bottom of the motor housing 
> case is a pain. It should not be that tight.
>
> 8) When removing the bottom bearing do NOT try to grip the bearing 
> from the inside race. Doing so risks nicking or cutting the armature 
> wires down there especially if the factory bearing was driven too far 
> and popped the circlip
>
> 9) Speaking of which make sure the circlip is proper on the motor 
> shaft. Sometimes it's bashed back.
>
> 10) Pull the bearing slowly, you don't need the bolt once the blade 
> hub is off.
>
> 11) I clean up the shaft with a wire brush on the grinder to get rid 
> of the crud, and put on the new bearing with a tiny bit of grease on 
> the inside and tapping it on with a socket plus wood buffer plus 
> hammer that's just the size of the inner race. Don't pound it too far, 
> just to the point where it touches the circlip. You can go too far and 
> drive the circlip down, then you have to pull it and start over.
>
> 12) Top bearing is easy to replace, just needs to be put on flush with 
> the shaft.
>
> 13) I put a thin bit of anti-seize on the new hub just so in 50 years 
> someone will try to remove it and go "wow this was simple. Thank you 
> old man from 50 years ago!"
>
> Now I need to find a fat motor top and assemble this with the 
> shattered magnet to see if/how it works. Then pull the new thin motor 
> so I can get the hub off of it, then the armature out, then take a 
> look at what I can do to press the high commutator bars back down....
>
> Never dull. Glad I have a stash of bearings, the old ones are really 
> in pretty sad shape. New ones are so nice and quiet....

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