McMillan 3hp dc motor over heats at the brushes…

Thread Starter

nitrous2020

Joined Sep 29, 2020
6
Hi guys,
I’ve followed/read several very useful treadmill threads and so wondered if you guys might have some insights for me.

Our treadmill was working (“ok”) but had laid idle for a few years. Was working but the motor was stalling out under load. It was also overheating to the point that the brush cover on the black lead actually melt. I changed the brushes.. but didn’t clean the commutator (which is pretty dark with brush dust) and it seemed to work ok… until it started smoking at the brush cover (it’s a 3hp cont McMillan DC motor)

someone on a treadmill forum suggested “a weak control board “. The board looks fine to me. I’m not even sure what a “weak controller” would be…. I have not put an amp meter clamp on the motor leads to see what it was drawing…

any thoughts that come to mind?
thanks
doug
 

Thread Starter

nitrous2020

Joined Sep 29, 2020
6
Good thought! Thanks
is the controller unlikely to be the culprit?
I’ve got replacement brush caps and new brushes. Will polish the commutator and scrap the commutator segment insulation.

once done, will try it out… tnx
 

Thread Starter

nitrous2020

Joined Sep 29, 2020
6
Do you happen to know what the brush housing is made from? It appears to be injection molded thermoplastic, but I suppose could be thermoset.
It's black, very sense and appears to be quite heat resistant.
Thanks
Doug
 
Top