"Leif Neland"
Phil Allison:
"Bob C"

I have an old 12 volt 3 phase model railroad motor


** You mean 12volt 3 pole ?

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.


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.

Back in the 90s, I raced 1/10th scale RC cars on both tracks and a
elodrome - 3 pole motors were the norm with 7.2 V SubC NiCd packs. The
motors lasted quite well.

Add one more cell and the motor life was cut by a factor of about 10, add
two more and the same motor was lucky to last two minutes.



..... Phil