The Ford Barn

Badpuppy · 11-06-2021, 09:35 AM

Could be as simple as worn out brushes.

Dkrahn · 11-07-2021, 03:49 PM

I have the carburetor off now for a few days. So it be a while before I respond with info. I cleaned up and put new ends on the wires. I was looking at these instructions before and I am confused. Not sure why you say only middle brush is movable. Seems like they all are spring loaded and riding on the generator arm where they should.

Dkrahn · 11-07-2021, 03:52 PM

brushes are good shape

Certimafied · 11-07-2021, 05:11 PM

They are all spring loaded to keep tension on the armature, however there is one brush that can be rotated up or down around the armature the other two brushes are stationary. That third moveable brush controls generator output.

I don’t have the points type cutout, mine had already been converted to the diode/solid state cutout. But I would imagine with battery disconnected and the points closed you could check continuity between the two sides of the cutout with a multimeter. With points closed there should be continuity with little or no resistance.

Patrick L. · 11-08-2021, 10:21 AM

The 'third brush' is the the smaller one and is mounted so it rotates to change the charge rate.

As mentioned, the other 2 normal brushes do not move. They are mounted stationary and only spring loaded to keep tension against the commutator.

Badpuppy · 11-09-2021, 09:33 AM

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Seems to me to be open field connection. Insulate third brush from armature and check resistance to ground = ~1.5 ohms. Could be bad ground connection to case at other end or splice between windings.

nkaminar · 11-09-2021, 11:12 AM

Dkrahn,

As others mentioned, the third brush rotates. Rotating it down increases the charging rate and rotating it up decreases the charging rate. Try change the third brush as I described earlier but make sure you view the ammeter while the engine is at a fast idle. If in doubt as to what a fast idle is, increase the rpm a little more but do not over rev the engine.

If that fails then take your generator to a shop to have it repaired or exchange it at one of the vendors, as I described earlier.

Dkrahn · 11-14-2021, 10:09 PM

OK Nkaminar
lines 4-7.. I started the engine to a fast idle. I moved the generator brush all the way down and still not charging. I then checked the voltage at the generator terminal and on a 20v scale it jumped from 1.8 to 18. So I am making the assumption I need to order a cut out, and the generator is all good..Agree?? I certainly appreciate your help.

I have about 3/8" of generator brush, so I also assume that is good..

Dkrahn · 11-14-2021, 10:11 PM

The brushes are showing 3/8" brush, past the screw..

nkaminar · 11-15-2021, 08:35 AM

Dkrahn,

Good work. You have done well. You now know how to adjust the 3rd brush. It seems that the generator is good. After you get a new cutout, you will have to reduce the charging (move the brush up) so that you have about 10 amps at a fast idle. If you drive the car long distances you may want to reduce the charging rate so you don't overcharge the battery. If you drive it at night a lot then you may want to up the charging rate to take care of the current the lights use. 10 amps is an average and Ford recommended adjusting it depending on how the Model A was driven.

Don't run the car without a new cutout and the generator hooked to the battery. The high voltage can damage the generator. The battery acts like a regulator on the generator.

eagle · 11-15-2021, 10:19 AM

A couple things... You replaced the ammeter as stated in previous post. If you put in a reproduction ammeter I would definitely test the old one and if its good, which is highly likely, put it back in. The repros are not very good quality. Same with the cutout, take it apart, clean it up, dress the contacts, check the insulator and put it back on. The originals are better than the repros. If you need a new one the diode type are better. If you can find it, a voltage regulator is the best.

11-06-2021, 09:35 AM	#21
Badpuppy Senior Member Join Date: Dec 2017 Location: Guthrie, OK Posts: 1,145	Re: Generator cutout Could be as simple as worn out brushes.

11-07-2021, 03:49 PM	#22
Dkrahn Member Join Date: Mar 2018 Location: Thorndale, Texas Posts: 88	Re: Generator cutout I have the carburetor off now for a few days. So it be a while before I respond with info. I cleaned up and put new ends on the wires. I was looking at these instructions before and I am confused. Not sure why you say only middle brush is movable. Seems like they all are spring loaded and riding on the generator arm where they should.

11-07-2021, 03:52 PM	#23
Dkrahn Member Join Date: Mar 2018 Location: Thorndale, Texas Posts: 88	Re: Generator cutout brushes are good shape

11-07-2021, 05:11 PM	#24
Certimafied Member Join Date: Aug 2020 Location: Belmont N.C. Posts: 85	Re: Generator cutout They are all spring loaded to keep tension on the armature, however there is one brush that can be rotated up or down around the armature the other two brushes are stationary. That third moveable brush controls generator output. I don’t have the points type cutout, mine had already been converted to the diode/solid state cutout. But I would imagine with battery disconnected and the points closed you could check continuity between the two sides of the cutout with a multimeter. With points closed there should be continuity with little or no resistance.

11-08-2021, 10:21 AM	#25
Patrick L. Senior Member Join Date: May 2010 Location: Largo Florida Posts: 7,225	Re: Generator cutout The 'third brush' is the the smaller one and is mounted so it rotates to change the charge rate. As mentioned, the other 2 normal brushes do not move. They are mounted stationary and only spring loaded to keep tension against the commutator.

11-09-2021, 09:33 AM	#26
Badpuppy Senior Member Join Date: Dec 2017 Location: Guthrie, OK Posts: 1,145	Re: Generator cutout Sponsored Links (Register now to hide all advertisements) Seems to me to be open field connection. Insulate third brush from armature and check resistance to ground = ~1.5 ohms. Could be bad ground connection to case at other end or splice between windings.

11-09-2021, 11:12 AM	#27
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 3,897	Re: Generator cutout Dkrahn, As others mentioned, the third brush rotates. Rotating it down increases the charging rate and rotating it up decreases the charging rate. Try change the third brush as I described earlier but make sure you view the ammeter while the engine is at a fast idle. If in doubt as to what a fast idle is, increase the rpm a little more but do not over rev the engine. If that fails then take your generator to a shop to have it repaired or exchange it at one of the vendors, as I described earlier. __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past.

11-14-2021, 10:09 PM	#28
Dkrahn Member Join Date: Mar 2018 Location: Thorndale, Texas Posts: 88	Re: Generator cutout OK Nkaminar lines 4-7.. I started the engine to a fast idle. I moved the generator brush all the way down and still not charging. I then checked the voltage at the generator terminal and on a 20v scale it jumped from 1.8 to 18. So I am making the assumption I need to order a cut out, and the generator is all good..Agree?? I certainly appreciate your help. I have about 3/8" of generator brush, so I also assume that is good..

11-14-2021, 10:11 PM	#29
Dkrahn Member Join Date: Mar 2018 Location: Thorndale, Texas Posts: 88	Re: Generator cutout The brushes are showing 3/8" brush, past the screw..

11-15-2021, 08:35 AM	#30
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 3,897	Re: Generator cutout Dkrahn, Good work. You have done well. You now know how to adjust the 3rd brush. It seems that the generator is good. After you get a new cutout, you will have to reduce the charging (move the brush up) so that you have about 10 amps at a fast idle. If you drive the car long distances you may want to reduce the charging rate so you don't overcharge the battery. If you drive it at night a lot then you may want to up the charging rate to take care of the current the lights use. 10 amps is an average and Ford recommended adjusting it depending on how the Model A was driven. Don't run the car without a new cutout and the generator hooked to the battery. The high voltage can damage the generator. The battery acts like a regulator on the generator. __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past. Last edited by nkaminar; 11-15-2021 at 08:40 AM.

11-15-2021, 10:19 AM	#31
eagle Senior Member Join Date: Aug 2011 Location: Eagle Bend, MN Posts: 2,025	Re: Generator cutout A couple things... You replaced the ammeter as stated in previous post. If you put in a reproduction ammeter I would definitely test the old one and if its good, which is highly likely, put it back in. The repros are not very good quality. Same with the cutout, take it apart, clean it up, dress the contacts, check the insulator and put it back on. The originals are better than the repros. If you need a new one the diode type are better. If you can find it, a voltage regulator is the best. __________________ "There are some that can destroy an anvil with a teaspoon and shouldn't be allowed to touch anything resembling a tool."