6 volt generator question

Charlie M · Apr 20, 2014

I've got a couple of 6 volt generators I've opened up trying to find out why neither work. One is a new one from a couple of years ago and never worked. The other one came on the tractor which hadn't run for years before I got it. Both are 3 brush generator and both have a regulator attached.I've been watching a good U-tube video on how to check these things but the video is for a 2 brush generator. My question is what does the 3rd brush do and do I need it with a regulator? All the tests I have done from the U-tube video have been OK so I'm not sure why the new unit doesn't work. The old one has some bare wires to the brushes so that may be the problem on that one.

John T · Apr 20, 2014

"My question is what does the 3rd brush do and do I need it with a regulator"

The physical location of the third brush regulates the rate of charge. The closer it is to the fixed brush the more charge, the further away the less charge. Some 3 brush are adjustable (can set third brush closer or further away from fixed brush)

Early 3 brush gennys were seen often when a full fledged automatic Voltage Regulator WAS NOT USED but instead only a simple manual Low or High charge selector light switch.

However, in later years they still used some 3 brush gennys even when they went to a full fledged automatic Voltage Regulator. Later they went to 2 brush gennys and full fledged Voltage Regulators.

COMMON PROBLEMS are the brushes are worn down too short,,,,,,,,the fields may be open or shorted out,,,,,,,,,,,,The splice may be open or shorted where the 2 fields connect together,,,,,,,,,the armature may be shorted to case. A physical inspection and an ohm meter can test for much of that while a growler may be necessary for more precise accurate armatures testing.

My troubleshooting procedure may help.

John T
John Ts Troubleshooting

Jim Becker · Apr 20, 2014

Given that you have 2 failing generators and one is brand new, chances are nothing is wrong with either one. You may have a bad regulator or, more likely, you have a bad ground. The problem could be caused by rust or by paint. Clean up all the mounting locations and check it out again.

6 volt generator question

Charlie M

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John T

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Jim Becker

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