Commutator Bar Shorts

[Hugh Heifer]

A quick question about electric motors. In this case the motor is the Windshield WIper motor out of my '71/'72 40.

The motor did not test so I figured I would start with the simplest thing first. I took it apart and cleaned it and replaced the brushes.

Still nothing.

Here is the question: When checking the commutator for shorts, is it correct that the mica between the commutator bars is there to prevent continuity between bars? I have found that touching one bar with juice, I get juice on all bars. Just want confirmation that this is a bad commutator?

 

[Hugh Heifer]

ttt

Anyone

 

[theo]

The commutator segments should be insulated from each other, but each segment is connected to a coil (winding) and I think it's more common for the windings to short than the commutator segments. Not sure how to test which is your case though.

 

[Hugh Heifer]

The commutator segments should be insulated from each other, but each segment is connected to a coil (winding) and I think it's more common for the windings to short than the commutator segments. Not sure how to test which is your case though.

I believe the only way to isolate the problem properly is on a "growler"

 

[Coolerman]

The FSM agrees with you... Been many years since I tested motor armatures with a hacksaw blade and a growler...

An alternator rebuild shop could test it for you.

 

[venpick]

holy... i got out my decoder ring and the outlook is good blue beer can hacksaw growler toss that fawker and buy a squeegee

 

[Hugh Heifer]

FYI - the motor I was testing that had continuity between commutator bars now functions. So the simple answer is, "Yes - there will be continuity between bars and testing it on a bench without a growler will more likely tell you nothing."

Merry Christmas

 

[Pin_Head]

There should only be continuity with bars 180 degrees apart on the armature. If there is continuity with other segments or the shaft, it is shorted somewhere. It can still run with some shorts, but it won't run as well.

 

[MongoATX]

A quick question about electric motors. In this case the motor is the Windshield WIper motor out of my '71/'72 40.

The motor did not test so I figured I would start with the simplest thing first. I took it apart and cleaned it and replaced the brushes.

Still nothing.

Here is the question: When checking the commutator for shorts, is it correct that the mica between the commutator bars is there to prevent continuity between bars? I have found that touching one bar with juice, I get juice on all bars. Just want confirmation that this is a bad commutator?

Do you happen to have a part # for the brushes on the '71/'72 wiper motor? Trying to get mine up and running and the brushes are flat dead!