I've spent the last 4 hours or so reading all about early Flathead generators and how they work, in an effort to get my T charging system working. I have the type of generator that has a bolt-on cutout on top, as shown in the picture below. I've got like 6 or 7 of these things and I'd like to bench test them to see if any might be good. I've read a lot of references to hooking them up to a battery to see if they'll turn like a motor, I know that's not a definitive test of how well they work but it's a good place to start since I have so many of them to try. But I can't find any reference to how EXACTLY I'm hooking them up to try to get them to "motor". They do not have any studs on them whatsoever. There's two wires coming out, one goes to a field coil inside and typically would get grounded to the generator's case using one of the bolts that holds the cutout on. The other wire goes to the third brush and would get hooked to the "ARM" stud on the back side of the cut out. Can anyone tell me how to hook these up to a 6V battery to see if they'll spin? There's tons of reference to this test on the internet but not a single reference I can find that tells me what specific wires to hook to what.
So apparently, through trial and error I've figured out that the method is to bolt the "field" wire down to the case using one of the little screws that holds down the cutout (which, when installed, is also screwed down to that same cutout screw), then jumper a wire from that same bolt to the positive side of a battery. Then use a jumper wire from the negative post of the battery (since this is a positive-ground system) and hook it up to the "arm" wire coming out of the generator (the one that would normally go to the back side of the cutout). The wires aren't labeled or necessarily color coded, if you don't know which one is which, you have to take off the little inspection cover sleeve thing and follow them into the generator. The "Field" wire will connect to one of the "field coils", which are the big coils that sit up inside the generator case and don't move. The "arm" wire goes to one of the brushes, which are the little spring loaded contacts on the back plate of the case. The spinning center part of the generator is called the armature, and the shiny brass end of it that the brushes ride on is the commutator. The brushes make contact with the armature at the commutator when it spins, that's why that wire is called "arm". I'm going to add some pictures a little later, maybe someone in the future will find it and this will help answer their questions, saving them the hours of guesswork I just had.
I’ve done it on a Ford tractor generator, but it didn’t have a cut out as I recall. I do remember when looking for the info there were a few different ways to do it, depending what you have. Good find and thanks for sharing!
Some pics to help explain what I had talked about earlier. This is how my jumper wires were hooked up to "motor" test the generator. "Field" wire bolts to the case, along with a jumper wire going to the positive battery terminal (for positive ground), negative battery terminal jumpered to the "Armature" wire, and the generator spins like a motor. If you're trying to figure out which wire coming out of the generator is which, you have to take off the little inspection band and trace them back inside. These next pictures show a generator that's all apart, you don't have to take the end plate off to trace the wires, it was just easier to show using this disassembled generator. In this picture I'm touching the "field" wire, which goes into the case and connects to the big "field coils" inside the case, those do not spin. In this picture, my toothpick is touching the "Armature" wire, which goes into the case and mates up to one of the brushes, which ride on the commutator end of the armature, hence the name. The wire colors mean nothing and they aren't marked, so you have to look for sure. If I come up with any more useful pics I'll post them, but hopefully, at some point in the future, this will help someone out and it won't take a day of struggling to figure out what can be easily explained with pictures and a few paragraphs.
Again, just for the benefit of anyone who might find this thread doing an internet search, what led me down this path was the use of the Stromberg E-fire 6V positive ground distributor. The car was running poorly at high RPMs, "breaking up" like it had a weak spark. I initially thought the distributor wasn't advancing but a check with a timing light confirmed that it was. I talked to the guy in England who makes the distributors (who was quite helpful and responded quickly, very good customer service I will say) and asked about my problems, he told me that the 6V distributors run "on the razor's edge" for voltage, meaning if your charging system works well they're fine but if you're trying to run it off the battery alone they can have issues. That's how I first discovered my generator wasn't working at all. So if you're reading this and you have a Stromberg E-fire 6V distributor and your car is running poorly, check your charging system first before blaming the distributor itself. Now that my charging system is working my distributor issues seem to be resolved. My car would dip way down under 6V when running with no generator (and the voltage was really uneven), now with the generator working it seems to be about 6.5V at idle and 6.7V at higher RPMs, and the voltage stays nice and even, which is all it took to get the distributor to work nicely. The info in this thread took me a long time to figure out on my own so I really hope posting it here helps someone in the future.
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