Blackened washing machine commutator
 

On Mon, 7 May 2018 12:14:16 +0100, "Dan S. MacAbre"
wrote:

The washing machine packed in this morning. Filled up with water, and
then nothing. I expected I was going to need to replace the motor
brushes (although they're only about two years old), but they are still
quite long. I noticed that the commutator lands (or whatever you call
them) were blackened, and that the face of one of the brushes was quite
rough, like anthracite. I also remembered that last night, it was
making what I now realised was an arcing noise, and not a chattering
noise that I'd normally associate with the brushes getting too short.
Anyway, I cleaned them up, and it's working fine now, but I'm wondering
what caused it. Is one of the brushes malformed? Or has low spring
pressure? Or something else?

If you have replaced the brushes previously did you use like for like.

I never suspected that brushes were anything special, but they are
made to a tight spec in a lot of cases, and although the end purpose
is the same i.e taking current to copper, there are significant
differences in binders/ fillers used. I assume it's dependent on
rotational speed, current and insulating material.

I noticed that with my last washer, the brushes went, I replaced them
and a few weeks later the pump went.

Coincidence, or is manufacturing quality so good it can hit the
expected lifespan with accuracy on multiple components?

AB

Blackened washing machine commutator
 

The washing machine packed in this morning. Filled up with water, and
then nothing. I expected I was going to need to replace the motor
brushes (although they're only about two years old), but they are still
quite long. I noticed that the commutator lands (or whatever you call
them) were blackened, and that the face of one of the brushes was quite
rough, like anthracite. I also remembered that last night, it was
making what I now realised was an arcing noise, and not a chattering
noise that I'd normally associate with the brushes getting too short.
Anyway, I cleaned them up, and it's working fine now, but I'm wondering
what caused it. Is one of the brushes malformed? Or has low spring
pressure? Or something else?

Blackened washing machine commutator
 

On Mon, 7 May 2018 13:20:16 +0100, "Dan S. MacAbre"
wrote:

Archibald Tarquin Blenkinsopp wrote:
On Mon, 7 May 2018 12:14:16 +0100, "Dan S. MacAbre"
wrote:

The washing machine packed in this morning. Filled up with water, and
then nothing. I expected I was going to need to replace the motor
brushes (although they're only about two years old), but they are still
quite long. I noticed that the commutator lands (or whatever you call
them) were blackened, and that the face of one of the brushes was quite
rough, like anthracite. I also remembered that last night, it was
making what I now realised was an arcing noise, and not a chattering
noise that I'd normally associate with the brushes getting too short.
Anyway, I cleaned them up, and it's working fine now, but I'm wondering
what caused it. Is one of the brushes malformed? Or has low spring
pressure? Or something else?

If you have replaced the brushes previously did you use like for like.


I bought brushes that were supposed to be the correct replacement for
the model (i.e. they were ostensibly identical to the old ones); but I
realise that there is always going to be 'good' and 'bad' stuff out
there, and that one pretty much takes one's chance when buying things
online. I've never seen one with such a burnt appearance before,
though. Even when worn right down, all the old brushes I've seen in the
past have a shiny surface.




Assuming the brushes were identical, can the suppression caps be
changed or swopped?

If you can fire up the motor while watching the aramature/ commutator
it might save a bit of work dismantling the thing a second time.

It probably is the brush, but if it's fairly easy to swop the caps to
see if the arcing follows the cap change, then it eliminates the only
other possibility.

AB

Blackened washing machine commutator
 

Archibald Tarquin Blenkinsopp wrote:
On Mon, 7 May 2018 12:14:16 +0100, "Dan S. MacAbre"
wrote:

The washing machine packed in this morning. Filled up with water, and
then nothing. I expected I was going to need to replace the motor
brushes (although they're only about two years old), but they are still
quite long. I noticed that the commutator lands (or whatever you call
them) were blackened, and that the face of one of the brushes was quite
rough, like anthracite. I also remembered that last night, it was
making what I now realised was an arcing noise, and not a chattering
noise that I'd normally associate with the brushes getting too short.
Anyway, I cleaned them up, and it's working fine now, but I'm wondering
what caused it. Is one of the brushes malformed? Or has low spring
pressure? Or something else?

If you have replaced the brushes previously did you use like for like.


I bought brushes that were supposed to be the correct replacement for
the model (i.e. they were ostensibly identical to the old ones); but I
realise that there is always going to be 'good' and 'bad' stuff out
there, and that one pretty much takes one's chance when buying things
online. I've never seen one with such a burnt appearance before,
though. Even when worn right down, all the old brushes I've seen in the
past have a shiny surface.

I never suspected that brushes were anything special, but they are
made to a tight spec in a lot of cases, and although the end purpose
is the same i.e taking current to copper, there are significant
differences in binders/ fillers used. I assume it's dependent on
rotational speed, current and insulating material.

I noticed that with my last washer, the brushes went, I replaced them
and a few weeks later the pump went.

Coincidence, or is manufacturing quality so good it can hit the
expected lifespan with accuracy on multiple components?

AB

Blackened washing machine commutator
 

On 07/05/2018 12:14, Dan S. MacAbre wrote:
The washing machine packed in this morning.Â* Filled up with water, and
then nothing.Â* I expected I was going to need to replace the motor
brushes (although they're only about two years old), but they are still
quite long.Â* I noticed that the commutator lands (or whatever you call
them) were blackened, and that the face of one of the brushes was quite
rough, like anthracite.Â* I also remembered that last night, it was
making what I now realised was an arcing noise, and not a chattering
noise that I'd normally associate with the brushes getting too short.
Anyway, I cleaned them up, and it's working fine now, but I'm wondering
what caused it.Â* Is one of the brushes malformed?Â* Or has low spring
pressure?Â* Or something else?

I remember the dynamo on my old MZ Trophy used to get through brushes.
The reason was that the commutator copper had worn down leaving mica
insulation a little proud between the segments, and this is what was
eroding the brushes. Disassembly followed by raking the insulation with
an old hacksaw blade, then polishing fixed it.

Cheers
--
Clive

Blackened washing machine commutator
 

On Mon, 07 May 2018 11:42:30 +0100, Archibald Tarquin Blenkinsopp wrote:

====snip====


I noticed that with my last washer, the brushes went, I replaced them
and a few weeks later the pump went.

Coincidence, or is manufacturing quality so good it can hit the expected
lifespan with accuracy on multiple components?

Probably not but I admire your cynicism. :-)

--
Johnny B Good

Blackened washing machine commutator
 

"Archibald Tarquin Blenkinsopp" wrote in
message ...
On Mon, 7 May 2018 12:14:16 +0100, "Dan S. MacAbre"
wrote:

The washing machine packed in this morning. Filled up with water, and
then nothing. I expected I was going to need to replace the motor
brushes (although they're only about two years old), but they are still
quite long. I noticed that the commutator lands (or whatever you call
them) were blackened, and that the face of one of the brushes was quite
rough, like anthracite. I also remembered that last night, it was
making what I now realised was an arcing noise, and not a chattering
noise that I'd normally associate with the brushes getting too short.
Anyway, I cleaned them up, and it's working fine now, but I'm wondering
what caused it. Is one of the brushes malformed? Or has low spring
pressure? Or something else?

If you have replaced the brushes previously did you use like for like.

I never suspected that brushes were anything special, but they are
made to a tight spec in a lot of cases, and although the end purpose
is the same i.e taking current to copper, there are significant
differences in binders/ fillers used. I assume it's dependent on
rotational speed, current and insulating material.

I noticed that with my last washer, the brushes went,
I replaced them and a few weeks later the pump went.

Coincidence,

Yep, hardly anyone gets that result.

or is manufacturing quality so good it can hit the
expected lifespan with accuracy on multiple components?

Nope, and the evidence for that is that hardly anyone gets that result.

Blackened washing machine commutator
 

On 07/05/2018 12:14, Dan S. MacAbre wrote:
The washing machine packed in this morning.Â* Filled up with water, and
then nothing.Â* I expected I was going to need to replace the motor
brushes (although they're only about two years old), but they are still
quite long.Â* I noticed that the commutator lands (or whatever you call
them) were blackened, and that the face of one of the brushes was quite
rough, like anthracite.Â* I also remembered that last night, it was
making what I now realised was an arcing noise, and not a chattering
noise that I'd normally associate with the brushes getting too short.
Anyway, I cleaned them up, and it's working fine now, but I'm wondering
what caused it.Â* Is one of the brushes malformed?Â* Or has low spring
pressure?Â* Or something else?

In my experience, worn washing machine motor brushes do appear to be
quite long UNTIL you compare them to new brushes!

When I had a Hotpoint that went through a set of brushes every couple to
three years I initially mistakenly assumed that the brushes were not
that worn when the motor first became intermittent. Removing,
inspecting and replacing the same always seemed to get the machine
working again for a month. In the end I always had a spare set and on
the first sign of a problem I immediately replaced the brushes.

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk