Thread Number: 18966
Odd Hoover Convertible Model 33 motor
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Post# 208968   12/6/2012 at 10:17 (2,053 days old) by kloveland (Tulsa, OK)        

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Recently, I took the hood of the 33 that was one of the prize vacuums in Sean Curry's mini meet. It appears that someone has drilled a hole in the upper portion of the motor and I'm not sure why they did this. I've never seen this before in any of my other Convertibles. Could it be for seating brushes?

Post# 208974 , Reply# 1   12/6/2012 at 11:39 (2,053 days old) by s31463221 (Frenchburg, KY)        

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I'm not sure what the purpose of the hole is, but I had a Convertible motor that had one in it too, that motor is long since gone, but when I found it I thought it was just a design flaw in the motor, but never really gave it much thought. Interestingly enough, yours is only the second motor I've seen like that and if memory serves right, it was a metal based convertible I took the motor off of. Couldn't begin to tell you the model number of it though. Thanks for starting this thread, I'll be interested to see what the reasoning behind this was too!

Post# 208980 , Reply# 2   12/6/2012 at 12:16 (2,053 days old) by madabouthoovers ()        

Just took the hood off one of my 652A's and there is no hole in this motor - I can only think maybe it was there for extra ventilation maybe?

I notice yours doesnt have a suppressor either?

Post# 208981 , Reply# 3   12/6/2012 at 12:34 (2,053 days old) by kloveland (Tulsa, OK)        

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I noticed that the motor also has a strong odor coming from the carbon brushes. The carbon brushes look like they have been replaced recently. The odor is very noticeable when using the attachments.

When I replaced the carbon brushes in my 704 it had the same odor. When I put the old carbon brushes back in the odor stopped. Could it be that the vac shop or individual who replaced the brushes put the wrong type of carbons in? The carbon brushes used in my older Convertibles have a gold spring and the newer ones have a sliver spring. The newer ones look like they could be used in a Kirby as well.

Post# 208983 , Reply# 4   12/6/2012 at 12:55 (2,053 days old) by kloveland (Tulsa, OK)        

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It's interesting that the UK models of convertibles had fabric bags. We had them way later in the later model convertibles. None of my convertibles have suppressors. Some of my Electrolux canisters have suppressors. I'm not sure why some had them and some did not.

Post# 208984 , Reply# 5   12/6/2012 at 13:16 (2,053 days old) by madabouthoovers ()        

I dont think the bags on mine are the originals, but I think they would have been fabric whatever the colour.

The carbon springs on mine are copper coloured - but I dont think it matters what colour they are. They are more likely to spark if they are new and not bedded in yet.
I noticed on a junior I was working on the other day that I got grease on the commutator from lubing the back bearing and it smelt of burning for a while afterwards - is there any way that bearing lube might have got on the commutator and is just burning off?
You need to hope that the armature aint arcing, or thats big trouble.

Post# 208987 , Reply# 6   12/6/2012 at 14:38 (2,053 days old) by kloveland (Tulsa, OK)        

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Just thought some of the newer carbon brushes might not work well in older motors. I've had the same experience twice! I have a couple of spare motors and two other model 33s, so I thought I would just switch motors. I didn't lube anything because it clearly says "Do not oil" or something like that on the top sleeve bearing. Hoover must have put that there for a reason. So, I just leave the top bearing alone.

Post# 209021 , Reply# 7   12/6/2012 at 23:32 (2,052 days old) by kirbyvertibles (Independence, KS)        

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This would very much make since, I would say a vac shop did this so they cold polish the armature when giving it a service. The best way to polish all armatures is to do it while the cleaner is running but some cleaners you just can't get to them.

Post# 383876 , Reply# 8   1/8/2018 at 17:03 (194 days old) by hooverU4089 (CT)        
I think I have an explanation!

I suspect the owner of this unit drilled the hole to insert a commutator stone to seat the new brushes. Check out my thread, the last couple of posts in which the use of commutator stones was discussed.


Post# 383934 , Reply# 9   1/9/2018 at 11:14 (193 days old) by Phaeton (Los Angeles )        
Sort of a common practice when needed

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Hello All,
Some re-builders and vacuum repair shops would do that when replacing carbon brushes and or replacement of the armature, so hooverU4089 is correct.
The owner of the shop I worked at for a few years in the late 70's years would do that only if the motor was arcing and sputtering.
On the 28 there was a paper like dust cover at the rear of the motor which gave access to the commutator which could be removed.
Canister and tank vacuums were less of a pain to seat the carbon brushes.
We would cut the bar down to a long piece about a 1/4" thick with a hack saw blade, like that small piece in the picture.
I have done this for years and worked with electricity since I was 14. I helped my dad back then pull wire as he was IBEW and taught me a lot.
I believe there was a way to do this when the armature was out of the motor in a jig that would hold the armature and spin it.
I know Ben Condo had one and I vaguely remember using it at the shop.
**Please understand it is done while the motor is running and for the unskilled and skilled a wrong move can shock you and could cause death.
Thank you for looking,

  View Full Size
Post# 383961 , Reply# 10   1/9/2018 at 16:41 (193 days old) by hooverU4089 (CT)        

My convertible is arcing considerably, so I and several other members feel this this process would be necessary.

This would be my first time using a commutator stone, so safety tips would be greatly appreciated.

Post# 383971 , Reply# 11   1/9/2018 at 19:31 (193 days old) by vacman1961 (North Babylon, New York)        

When I had my Vac Shop, we used to chalk the commuter on all vacuum motors, especially after we changed the carbon brushes, We made a special top bearing plate that we used to chalk the motors. We took an old bearing plate and drilled a hole in it, removed the cooling fan from the motor and while the motor was running suck a piece of 1/4 X 1/4 inch commutator seater in there, after we were don't, we removed the bearing plate, blew all the dust out of the motor with a compressor, replaced the cooling fan and reinstalled the original bearing plate. It is amazing how much better a machine runs after you cut the commutator, no arcing, no carbon brush smell, higher RPM's.

Post# 383980 , Reply# 12   1/9/2018 at 22:17 (193 days old) by hooverU4089 (CT)        
I think I get the idea.

Do you (could I, perhaps) use the old Hoover bearing (I plan to replace it), drill a hole in it, and just stick the stone in the small gap between the commutator and the plastic housing around? A picture would definitely help if possible.

As mentioned in my other thread, I sanded the commutator with 1500 grit wet/dry sandpaper and then followed a brush seating procedure, suggested by some YouTube videos, in which I stuck a strip of the sandpaper around the commutator with the rough side against the brushes while turning the armature in place with a low speed drill.

When I ran the unit, it sounded very raspy, definitely not that classic Hoover purr! I noticed that the motor's RPMs were not quite as high as before and the sparks coming from the brushes looked like a sparkler show, or an angle grinder on metal!

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