31 model A generator field wiring

[Billybob57]

I was given a 31 model A generator that was unwired. My question is where do the two field wires connect to? From what I've found one appears to connect to the 3rd brush and one to a ground. Is this correct and if it is, where should the ground wire be connected? And does it matter which one is the ground and which is the 3rd brush? Thanks.

 

[rotorwrench]

That is correct. The third brush controls current to the field as it receives it from the commutator. It receives more or less current depending on the position of the 3rd brush in relation to the fixed brush that is connected to output terminal. The opposite fixed brush is grounded to the rear bearing/brush housing plate. Moving the 3rd brush toward the output fixed brush which is usually rotating it down, increases the amperage output. Moving it farther away from the output brush decreases the amperage output.

This link is a good one. https://lesmodela.files.wordpress.com/2017/10/wiring-diagram.pdf

On the later cylinder type generators, there were two ways to ground the one end of the field coils. One was grounted with the output terminal assembly to the case there and the other was to a ground screw that was attached to the case in a separate location.

This link has a video of a generator overhaul. https://www.santaanitaas.org/technical-videos/