32E generator, will it hurt to run without the third brush

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32E generator, will it hurt to run without the third brush


Post by King » Wed Feb 09, 2005 1:24 pm

I recently pulled my three brush generator to clean it up a bit. When I removed the end cap about 1/2 of the third brush carbon fell out. Question is, will it hurt to run it without the third brush until the new one arrives?


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Re: 32E generator


Post by VintageTwin » Wed Feb 09, 2005 2:56 pm

Seems like since it's the regulating brush, with it gone, you would have unregulated voltage. Might fry the gen.

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Re: 32E generator, will it hurt to run without the third bru


Post by awander » Sun Jul 24, 2011 3:27 am

The way the 3-brush generator works:
-With the light switch OFF, one of the 2 field coils(the "regulating" coil) gets a voltage from the 3rd(Regulating) brush(the other end of this field coil gets full generator voltage). This excites the field, and allows the generator to , well, generate. In this scenario, the 2nd field coil(the "Shunt" coil) is grounded on one end, but the other end is not connected, so it contributes nothing to the field.

-when the light switch is turned on, the Shunt coil gets full generator voltage on the end that was unconnected. This allows the shunt coil to contribute to the field, and increases the generator output.

With the 3rd brush missing, the Regulating field coil will get no voltage across it(the end that should get a voltage from teh 3rd brush would be, in effect, unconnected), and so the generator will not generate, unless you turn the lights on(which activates the Shunt field coil). And with only the Shunt Field coil contributing to the field, the generator output will be low. This will not damage anything, but you won't get too far without recharging your battery.

I put about 150 miles on my '52 last week, and somewhere in there, the wire between the 3rd brush and the regulating coil opened up, leading to the symptoms described above. No harm done, except to my pride.

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