Question about 6 volt charging generator

Have 6 volt 3 brush generator on Farmall C that Had bad bearing. I replaced bearing and bushing and install new brushes.
A low idle it will discharge about 5 amp I have to bring throttle up to low mid range and it will charge about 10 amps.
Can I by adjusting 3rd brush get it to charge at low idle? Or should I not worry about it.

Discharging 5 amps is a bit much unless the lights are on. The cutout in the regulator should "cutout" the gen's connection to the system when the gens output voltage gets about 1 volt less than the battery voltage. Which should be ~6.3 volts when stopped,. The discharge might be expected to be 3 .5 amps (accounting for the ignition draw) The cutout (in the VR can be adjusted with testing instruments and experience.
If you idle the tractor a lot, the best real approach might be a alternator (6v are available). If you don't Idle much ignore it. Jim

There is no way to adjust the stock 3-brush generator to make it charge at idle - it's just how a generator charging system works.

5 amp discharge at idle is a bit high....3 - 4 amps is more normal. However this can simply be inaccuracy in the ammeter itself (its NOT a precision current measuring device!)

If the battery stays up I'd not worry about it. But try to avoid excessive idling (which gradually drains the battery). Better to shut down the engine then restart when needed than to let it idle for long periods.

We do agree. Jim

Thanks guy I will see how it goes. Easy to just keep the Idle higher. I didn't know if the brushes had something to do with that.

Oldiron, yes as others have mentioned the cutout relay is what prevents that. The cut out relay can also be referred to as the reverse current relay because it should prevent discharge due to the current reversing from charge mode to discharge mode. You may want to watch your amp meter. If it's discharging at an idle the cut out relay may not open to stop the discharge when you shut the engine off since it's already in discharge mode. Sticking contact points or incorrect spring tension on the cutout relay will cause this discharge. Reverse current is the current going into the generator at an idle or (even when engine is stopped if cutout is not working correctly). But when the generator starts charging the current flows out of the generator to the battery. The cutout/reverse current relay is the main contact switch (which always has battery voltage present) between the battery and generator. If the contact on this relay stick closed it can let current flow into the generator when engine is off or at low idle when generator is not charging above battery voltage. Basically current flows both ways thru the cutout and if the spring tension is too weak or points are stuck it won't pull the contact open in time to open the circuit when current starts to flow the other way. Current flow direction changes instantly that's why adjustment is important on the cutout relay.

The output of the generator CAN be changed by moving that third brush. That is the intended purpose of it, but in reality it makes very little difference.

You can ONLY adjust a three brush generator IFFFFFFF it has an "adjustable" third brush, some are fixed in place no adjustments. If adjustable the closer its set to the fixed brush near it (within specs and limits) the greater the charge

You might insure the belt is good n tight and all the wiring especially grounds are good.

If the tractor has an extreme slowwwwwwwwwwww idle you might crank it up just a tad

Maybe not worry to much if it keeps the battery charged

John T