Phil Allison har bragt dette til os:

Typically, 12 volt DC motors have 5 poles - with only three, arcing
across the comm segments will be severe with 12V input.

Depends.

** What I wrote is accurate.

What is typical can be depending on many factors, including date.


** What I wrote is accurate, what you are saying is absurd crap.


The model racing cars my dad imported while I was a kid (Jouef) had 3
poles,

** IME they spend only a faction of the time with 12V applied.

while the trains, especially the higher class models, had 5 poles, to be
able to drive more slowly and smoothly.

** Not the reason at all.

It's easy to get 3 pole motors to run slowly, SCR and pulse controllers
have been doing it for decades.

It was also decades ago, i was a kid.

** Try making an actual point sometime - pal.

If you re-read the original post:

I have an old 12 volt 3 phase model railroad motor that has a dead spot
between two segments of the commutator.How can i fix it because to get a
replacement is almost impossible

The "old 12 v railroad motor" might be so old my points were valid.

Leif


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