Autolite 2-tower regulator questions ....

I have an 6V Autolite generator (model 4809) that has an Autolite 2-tower regulator that attaches directly to the generator case. One of the towers is a generator cut-out, the other tower is controlling voltage or amperage I think, but that's really not my question.

If you click on the link below you will see a picture from the internet of the same regulator that someone had for sale. In the picture, you will see a small cylindrical metal fuse cap (I think it's a fuse cap) on the lower right of the base. Someone has put a little metal "blank" inside to replace the fuse, not sure why ..... maybe he couldn't find a fuse that fits. It seems like a shorter fuse length than most glass-bodied fuses would be.

Second, on the right side base (barely visible in the photo) is a ceramic or carbon block or bar. I suspect it is some kind of a resistor. The block on my regulator is broken, the middle 1/3 is actually missing but the two ends are screwed to the regulator. So two questions ...

1) What is the purpose of the fuse I describe assuming it is a fuse) ??
2) What is the purpose of the carbon or ceramic resistor block (assuming that's what it is) ??

This will make more sense once you see the photo in the link ....
Untitled URL Link

Here's a second photo from a web search of a similar regulator (not exactly the same for wiring hookup location) but it shows the ceramic or carbon resistor block on the side much better. Here's the link for a better photo ....
Untitled URL Link

A resistor on a regulator is often used to provide a base level charge rate. Autolite generators are often B type circuits that use an internally grounded field in the generator, and voltage supplied from the regulator. Very different than the typical Delco A type system. A generator is not self current regulating. They will burn up when trying to do more than intended unless a current limiting aspect is built into the (non-cutout) tower, or the design is moderated by a third brush system. Alternators are self limiting to their amp rating. Though not common, a fuse in the regulator applied to the armature output would prevent meltdown. A shorted fues holder would not. Jim

The two charge regulators replace the 2 position switch for charging using a 3 brush generator. It will switch the resistor in and out of the field circuit to control the output voltage and the charge rate. The voltage, and therefore the charge rate, will be either high or low, only two choices with this type of regulator. The current is limited by the 3rd brush.

The fuse is to protect based on the FIELD current not the output current.

For the regulator in your first link the fuse should be a 5 amp fuse and the resistor is 2.85 ohms.

All "A" circuit that I know of.

Thanks JA .... this generator is likely of the type you mention. Obviously, this little metal fuse that someone fabricated was subbing in for a proper fuse, like I said it would be shorter than the normal glass-type fuses I have had experience with. And if the carbon block resistor I mentioned is there to limit something, then for sure it is not working since it is in two pieces separated by air space.

When I run my Massey Harris 20 tractor (this generator and regulator has been robbed from elsewhere), the generator charges but at a very high rate, at higher revs it will pin the ammeter at close to 30 amps. Once it is at those higher revs, the needle will fluctuate wildly. Reducing the engine revs steadies the needle and it drops back to about 10-15 amps.

The actual specs for this generator are 3.8 to 4.0 field current amps ..... with an 8V output with 14-16 amps of charge. This is all Greek to me though. Anything more you can add is appreciated.

There should be letters in addition to the 4809 on your generator tag. It should be a 3 brush generator and the output current is self limited. The field current is why the TC regulator has a field fuse.

You may want to double check to see if you have a 3 brush generator that will work with that regulator.

Electro .... you mention 3rd brush, this generator has a third brush but perhaps is not "adjustable" like other ones I have dealt with, does
that make sense? Those generators had the light switch built into the charge control system.

So it would appear that I should find a 5 amp short fuse for the missing one (replacing the steel plug) and then a 3 ohm external ceramic
block-type resistor, I have some of those here at home. I don't think those carbon block type resistors are available anymore like the
original ones on this regulator. Perhaps this might solve some of the crazy readings and needle jumping I described in another reply I made
to JA. Once again, any follow up replies are welcome. Thanks ....

Electro, yes additional letters ...... GBM 4809 B 5 if that makes any sense. Yes, the regulator is TC 4324.

Resistor on side could likely be the limiting/regulating resistor for the field circuit of generator.

Don't know what it is on, but if it were mine (one man's opinion), at that price I'd be looking for an alternator.

RV ..... that's just a photo from the internet that I found to clarify my questions about the fuse and resistor. I'm not buying anything. There certainly are crazy prices ..... I think this one was from an Indian Motorcycle which would explain the price probably.

I think Deere used a 5 ohm resistor so if the three doesn't work out you might try one of those.

Never seen one of those Autolite relay's before so thanks for the pic. Basically the same as Deere systems just the components are all on the relay instead of being on the relay, switch and harness.

Hi again Electro ..... I posted the question immediately below here on the Tractor Talk forum just a few minutes ago (Monday suppertime).
I'll post it here as well in the original thread on page 3 today just in case you miss it in today's post. Here goes ... I hope you reply
to either one.


You replied a few days back to a post I had made here on Tractor Talk regarding my Autolite generator and regulator (current regulator I
think). You mentioned that the outside carbon "brick" resistor on the regulator had an approximate 3 ohm resistance value. Here's your
reply ....

"For the regulator in your first link the fuse should be a 5 amp fuse and the resistor is 2.85 ohms."

Sounds to me that you know what you're talking about. Here's my question ... How do you know (or where did you get the info) that the
resistance value of that resistor block is about 3 ohms? If you reply, I will tell you the reason why I ask this question.

Looking forward to your reply .... Crazy Horse