Generator Questions

Afordman31

Afordman31

Well-known member
My generator on my Model A quite working while driving home the other night, I had two miles to go so I drove on home. My Dad said I should have unhooked the wires on the battery side of the cutout and taped them together, then made a jumper wire from the armature terminal to the screw that mounts the cutout to the generator case, thus creating a ground. He said driving without charging could cause the generator to throw lead and ruin it. I don't doubt this so thought I would share.

Another question is this same generator will motor when you hook a
battery charger to it, the positive to the armature terminal and the negative to the generator case. I thought that if they would motor that the generator would be a good one that would also charge, I guess I was wrong. I have a generator test stand made up and it won't charge using the stand, so the problem isn't in my Model a wiring. Maybe someone could enlighten me as to why it won't charge and still motor before I disassemble it to try and figure it out.

I also have a generator that has the armature terminal near the pulley end and not the brush end. This makes the cutout 180 degrees different from the other generators I have. Is this a different year, or manufacture? It looks (pulleys and end cap) to be Model A. I put this one on my A but had to mount the cutout the other way.
 
The 1929 thru early 1930 generator, which followed the earlier Powerhouse, did look like the early 30 thru 31 generator but did mount the cutout differently, did have a different taper on the armature shaft where the pulley mounts, and did have a slightly different back plate.
 
Making the generator motor is a good sign, but not proof that the generator is good. When you made it motor by connecting the negative to the case, you polarized the generator backwards, so you should repolarize the generator the correct way, with + ground. Does the generator charge if you jump across the two cutout terminals? If yes, then try another cutout or repair this one. If not, then take the generator apart to check it out.
 
Tom Wesenberg said:
Making the generator motor is a good sign, but not proof that the generator is good. When you made it motor by connecting the negative to the case, you polarized the generator backwards, so you should repolarize the generator the correct way, with + ground. Does the generator charge if you jump across the two cutout terminals? If yes, then try another cutout or repair this one. If not, then take the generator apart to check it out.
Click to expand...

Thanks Tom
I now can see about polarizing the wrong way. My cutout has a diode installed, I checked it with a continuity meter and it is good, continuity one way and not the other. I put the cutout back on my Model A with another generator, started the car and set the third brush. Got my charging back. If brushes look good and not frayed wiring rubbing, where else should I look?
 
You can lift the adjustabe brush off the commutator and slip a piece of paper under it to isolate the field windings. (If the generator is apart, of course you can skip this step). Then connect a battery charger + to the case and - to the wire on the adjustable brush. A good field winding should draw about 4 to 5 amps. If this checks OK, then use a growler to check the armature. If the armature has thrown solder, you may get lucky and be able to resolder the wires at the commutator bar, or they may still have enough solder to work OK.

Check for continuity between the commutator and armature shaft. There should be NONE. Do the same for the field winding, but you will have to remove the ground end of the field winding to make this check.

Sometimes the twisted connection between the two field coils isn't a good soldered joint.

Make sure the commutator bars are smooth, not burned, and undercut at least .006" with no grit, carbon or copper in the undercut. Make sure the brushes ride square to the commutator, not cocked in the holder, or with a bent holder.

The long side of each of the 3 brushes is mounted AWAY from the pivot point of the brush holder, and the thin brush is the adjustable brush.

Make sure you don't mistake the 2 wires that connect to the brushes. I've seen generators burned up because some shop put the field wire on the output brush, instead of the adjustable brush.
 
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Tom Wesenberg said:
You can lift the adjustabe brush off the commutator and slip a piece of paper under it to isolate the field windings. (If the generator is apart, of course you can skip this step). Then connect a battery charger + to the case and - to the wire on the adjustable brush. A good field winding should draw about 4 to 5 amps. If this checks OK, then use a growler to check the armature. If the armature has thrown solder, you may get lucky and be able to resolder the wires at the commutator bar, or they may still have enough solder to work OK.

Check for continuity between the commutator and armature shaft. There should be NONE. Do the same for the field winding, but you will have to remove the ground end of the field winding to make this check.

Sometimes the twisted connection between the two field coils isn't a good soldered joint.

Make sure the commtutator bars are smooth, not burned, and undercut at least .006" with no grit, carbon or copper in the undercut. Make sure the brushes ride square to the commutator, not cocked in the holder, or with a bent holder.

The long side of each of the 3 brushes is mounted AWAY from the pivot point of the brush holder, and the thin brush is the adjustable brush.

Make sure you don't mistake the 2 wires that connect to the brushes. I've seen generators burned up because some shop put the field wire on the output brush, instead of the adjustable brush.
Click to expand...

Tom, thanks again. I am sure your information will be helpful when I open up the generator. I appreciate you enlightening me on the subject.
 
I also have a generator that has the armature terminal near the pulley end and not the brush end. This makes the cutout 180 degrees different from the other generators I have. Is this a different year, or manufacture? It looks (pulleys and end cap) to be Model A. I put this one on my A but had to mount the cutout the other way.[/QUOTE]


I also found in Brattons Catalog that the terminal post was located near the pulley end from October '28 to April '30. The terminal post near the rear of the generator April '30-31
 
Bratton's is right, the generator up to April 1930 had the terminal in the front and it also used a ball bearing in the rear. After that the rear used a bushing with an oling wick.

Be extra careful on the generators with the terminal in the front when you put it back together, since the output wire is taped to the field coil, it makes it much easier to mix the two wires up. If you accidentally install the field wire to the output brush and the output wire to the adjustable brush, you will cook the generator in short order.

I've seen shops make this mistake 4 times in the past few years.
 
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