Generator question

D

Dennis/CT

Senior Member
Hi Guy's,generator is rebuilt,hooked up voltage to it and it motors the correct direction.Here is the problem,took the generator off my engine,that charges fine,took off the cut out,which works fine too,and put it on the rebuilt generator and put back on the engine.The generator charges and adjusted the third brush,at idle the ammeter needle is steady, at a higher RPM the needle jumps from one end to the other end.I remember a post on this and searched the forum but could not find tne post. This generator will be going on my rebuilt engine that will be ready sometime in September. Any and all help is appreciated. Thanks to all,Dennis/CT
 
Sticky brush?
Weak brush spring?
Commutator not centered?
Loose connection?

Electrical can be tough without being there.
 
It could be any of the things that Tom said. Sometimes the brushes are not fitting the commutator just right. You can remove the generator band and CAREFULLY with the engine idleing hold some light pressure on the brushes one at a time to allow each brush to wear in a good fit to the commutator. If the brushes don't match the curve of the commutator the brushes can bounce at higher speeds and cause the needle on the ammeter to fluctuate.
 
I agree, it can be any one of the things the boys said.. You could also fit the brushes to the commutator with some emery cloth or fine sand paper, but, you'd have to remove the generator and the rear plate to do this.. Wrap a short length of the paper around the commutator between it and the brushes and turn the commutator/armature back and forth to sand down the brushes..
 
i was at a generator shop one day and watch them fit some brushes he took a wood end stick while the car was running and push against the brush, I thought this was crude but is worked
 
Its an old mechanic trick and works good. I always use my finger. Years ago I tried it with a screwdriver, the screwdriver slipped and messed up a good armature.
 
I had the same problem.I set the third brush to give a 15 amp charge which caused the needle to fluctuate at revs.Lowered charge rate to 10 amps and now the ampmeter is steady.What is your generator set to? Vic NZ
 
Hi Vic, sorry I don't have a meter to go by just the ammeter in the car.At an idle it is around 5 amps rev it up and before it starts to jump it is around 15 amps.I haven't tried to set the brushes yet. Thanks for the input
 
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