Hoover Model 707 Motor Hums, But Doesn't Turn

[whistle1]

Since it was my first post, I inadvertently posted this within another thread instead of creating a new one. Despite that, some people there were nice enough to respond. I also wanted to post it here to get some additional advice.

As noted in the title, the vacuum motor hums, but doesn't turn.

I disassembled the vacuum and checked for obstructions - none were found. I reassembled it and it ran fine; but only for several minutes. After that, it was back to just humming, but the motor wasn't turning.

Some people suggested that worn carbon brushes in the motor can cause the vacuum to run intermittently or not at all. I know where the brushes are (and even removed them) when I was checking for obstructions. Since I didn't know they could be causing the problem, however, I didn't really inspect them.

They didn't appear appreciably worn, as they looked to be almost in contact with the commutator. Of course, I have no idea how long new brushes are supposed to be.

Is there a way to tell they are bad simply by looking at them? Is there a way to test them (e.g., with a continuity meter)? Should I just assume they are bad and replace them?

Any advice would be greatly appreciated.

My Mom has had this since new and would hate to have to get rid of it.

Thanks.

 

[super-sweeper]

yes,

As I started in your previous thread, below is an example of a worn carbon brush. These wear down over the many years, and from how you describe it, you should defiantly look into having them replaced. As seen below, this brush has worn down to quite a degree. These brushes should be much longer than below.

 

[whistle1]

Thank you for the response. About all I can see on the picture you provided are the springs - and a little bit (the brush?) on the end.

The ones I am dealing with do NOT look like your picture. They are certainly much longer. If I can get hold of a digital camera, I will try to take a picture of them and post it here.

 

[vaclover]

.....

If there's no obstruction and the armature is turning free,the motor is starting to burn out. The insolation between the windings is braking down with extreme heat and thats causing an uneven magnetic field, it acts as a electro magnet so the armature can't spin when switched on. I can't say for sure that's the problem but that's what it sound like and that's my experience with electric motors. You can test it by measuring the ohms of the field coils.if the one is much higher or lower than the other one that's your problem.

Hope you'll get the problem quickly

Ruan

 

[super-sweeper]

if this motor cannot be fixed,

Then a new one (or even used!) Will be WAY more worth it then a newer, junky vacuum!



http://www.vacsew.com/hoover-convertible-motor-43574140.html#product_tabs2

 

[bnsd60m9200]

try repacking the lower bearing with new good grease and oiling the top bearing. it should work find after. if it worked but slowed down, the bearings need service badly. i had this happen on a 1076 once that i own. if it ran and stopped running and doesnt smell funny when it hums, the field coil is fine.

Will Hemb

 

[whistle1]

Thanks to those who offered advice.

As a follow-up, I removed both carbon brushes and found them each to be about 1/2-inch long. I'm not sure how long they are when new, but replacing them probably can't hurt.

If replacing them doesn't correct the problem, I'll be back...

 

[beko1987]

My 262 slowed down dramatically in use. I found the coil faces were thick with dirt and grease. A good cleanup later and it was running like new.

It span freely by hand but when the crap got hot it obviously slowed things down.

I did a thread on it, search for hoover 262 under my username.

 

[davetranter]

Motor draws current, but doesn't run

Motors with worn brushes don't generally 'hum'... They tend to 'buzz' or 'fizz', producing that characteristic AC arcing sound. If the armature spins freely by hand, this seems to indicate that one (or both) bearings are on their way out, and the magnetic field is pulling the armature into contact with one of the pole pieces when power is applied. This is a very common failure mode for 'Universal' type motors. New bearing, 'bodge' or R.I.P. I'm afraid.... :-(

All best

Dave T

 

[vaclover]

......

Dave your version makes more sense!If the carbon brushes is worn out it will arc around the commutator.Maybe its the bearings that's worn out, when electricity is applied it pulls the armature against one of the fields and it can't spin. I've got a carpet shampooer that spinned slowly and make a loud humming noise when switched on the next moment it was smoke everywhere. So don't let it sit humming for too long.Otherwise it will burn out.

 

[whistle1]

Thanks for the additional advice.

I will have to reassemble the motor to determine if the motor is humming or actually buzzing - as one person noted there is a difference.

As far as the armature is concerned, I can spin it by hand, but it does not spin freely or easily.

 

[whistle1]

Well, I reassembled the motor and turned on the vacuum.

Based on what I'm hearing, I would have to say that it is more of a "buzz" than a "hum".

So, does this then point back to the carbon brushes?