12 volt electrical diagram for a 420

[theshanmand1!]

howdy all,

my 58 420 was converted to 12 volt b4 I purchased it, the 6 volt amp meter was left in it & hooked up to the regulator, wich I think is original & 6 volt also. so when I put new gauges in it, mechanical temp, oil pressure, & a 12 volt ammeter, I unknowingly hooked it up the same way as the old one, and something smoked, now she wont even go click.
one of my buddies said that since its 12 volt I shouldn't need a regulator.

I cant find a wireing diagram for 12 volt for my 420 only 6 volt.

could one of you fine gentlemen enlighten me, thank you in advance.

[jtrichard]

need pics of the alternator to tell if you need a regulator ....as for the amp meter it is NOT voltage sensitive..... i don't think you will find a 12v wiring diagram for a 420 but all you need is a generic 12v diagram with alt and point type dist.

[theshanmand1!]

I researched it and found out that I do have a 12 volt single wire G.M. style alt.
and because I don't have any accessories, such as lights, etc. I shouldn't need a regulator.

next step will be to clean up the wiring

thank you for your help, and have a happy new year!

[Lavoy]

That is not totally correct, with any charging system, you will need a regulator, in your case it is contained within the alternator, accessories have nothing to do with regulator itself. Even if you had lights and a stereo on the crawler, you would still not use the factory regulator, there is no way to hook it up anyway.
Lavoy

[theshanmand1!]

Ok, good to know, thanks lavoy.
Happy new year to you all & go seahawks!

[Stan Disbrow]

Hi,

Except for the M with that third brush. I suppose you can call the gassing of the battery the regulator in that case. That is all there is....

Stan

[Lavoy]

Good call Stan, forgot about cutouts.
Lavoy

[theshanmand1!]

hi Stan, & Lavoy.

would you too be kind enough to explain what it is that you just posted, because it went rite over my head

thanks again,

Shanon

[Stan Disbrow]

Hi,

Well, all generators and alternators have field coils that build a magnetic field. This is what produces the current that charges the battery. The regulator sits ahead of the field coil raising and lowering the current in the field, so the battery sits at a given voltage.

This is a more sophisticated way to do it, but fits almost all of the machines we talk about here. I recalled the older way it was done on the M series. They have field coils, but the power to feed them come from a third brush on the armature. This is a fixed power - no regulator - feed and the current produced by the generator is set by rotating the band that holds that third brush.

My comment is that in this system, any overcurrent into the battery will produce excess gas as it converts the water into hydrogen and oxygen. In effect, this is the simplist form of voltage regulation there is.

The term cutout is referring to how the case of the generator has, well, a cut out section in it to allow the adjustment of that third brush to set the charge current.

Not to be confused with the cutout relay in the later electromechanical voltage regulators....

In retrospect, I probably should not have mentioned it. It would only confuse the discussion of modern internally regulated one-wire alternators. Not many folks here have M series machines with their differences that don't really make much sense these days.

However, it popped into my head, so I stuck in my two cents!

Stan

[theshanmand1!]

Hi Stan,

thank you for taking the time to explain that to me, I want to learn as much as I can about these old work horses. and I love listening to my elders,as you have more experience and wisdom to share. thanks again.
shanon.

[whiteclipse16]

I'm glad you mentioned it Stan. I makes pretty good sense to me. The voltage regulator and charging system has always been slightly mysterious to me and it's kind of tough to find detailed information on it.

Do you have any pictures of the generator with the "Cutout" section? I'd like to see this.

[Stan Disbrow]

Hi,

The only one I have is on my M, so the third brush band is in place. You can't see the cutout in the housing. Maybe Lavoy has one on the shelf with the band off of it.

As far as how they work, whenever a current passes thru a wire, it produces a magnetic field. Whenever a wire passes thru a magnetic field, there is a voltage and current induced in the wire.

So when we run a current thru the field coil, it makes a magnetic field. Then, as the armature rotates, the wires in it cut thru that mag field, and voltage and current are produced. That, in turn, is put into the battery. So, we convert mechanical power into electrical.

As the battery charges, the power in the field rises, and the output also rises. This is a positive feedback loop, and will cook the battery if it is not throttled. Enter the voltage regulator. In most of these old machines, that consists of two relays. One is the cut out relay that drops all power to the field coils when the generator stops rotating. The other is the regulator relay.

It has a resistor, usually wire wound, on the bottom side. It is calculated to lower the current in the coil such that it opens the contacts at a certain voltage. This allows the generator to put out whatever power is necessary to run the load. Like ignition only, or ign plus front lights, or both of those plus rear light.

With the old three brush gen, it has two output levels, selected by the ign switch. Lo and Hi charge, and Hi is barely enough to run the ign plus two light bulbs. This is why M tractors only had one front light and one rear, or two fronts and no rear.

Obviously, too, all the parts are figured out for a specific voltage. You cannot mix 6, 12, and 24 volt parts. So if you change the battery to 12 volts and put on an alternator, you disconnect the 6v regulator behind the dash. This is easy these days as the alternators have their electronic regulators built in. All you need do is hook that one terminal on the new alternator to the new battery. Leave the old wires taped off somewhere.

Now, generators vs. alternators.

Generators are direct current by nature. They have armature coils on the shaft, called a rotor, and field coils in the housing, called the stator. There are permanent magnets inside the windings of the field coils. These are really iron plates, and turned into fairly weak magnets by running some current thru the field coils. This is polarization. It was important in the days when some were positive ground and others negative, as you could change it as necessary.

As the rotor turns, it cuts the magnet field, and when rpms are high enough to raise the output voltage far enough, the cut out relay in the old regulator pulls in and sends battery power to the field coils in the stator. Most of you probably see the ammeter at zero or below on start up, then see it jump as the throttle is increased.

As the battery voltage rises from the starting drain, you see the ammeter drop. This is the regulation relay in the regulator doing its thing.

Alternators are somewhat different. Two things are different. Instead one set of DC windings, there are three sets. And, they produce AC instead of DC. There are diodes inside to convert the AC into DC.

Another difference is the field coils are in the rotor and the armature coils are in the stator. This is because as the power load kept going up, it overran the ability of brushes to carry the much higher current. There are no iron plate magnets, either. You have to have a good battery to fire off an alternator.

Yes, there are some alternators that incorporate a small, separate, DC generator on the end of the shaft to make them self exciting. Probably not going to put one of those on a crawler, tho.

Used to be that alternators used external regulators which work exactly like they did on generators. Most of those had a third relay that regulated by current alongside the one that regulated by voltage. Later on, they became transistorized, but still external. Eventually, they stuffed the regulator into the alternator housing.

I hope that was not too long winded.

Stan

[Lavoy]

The cutout on the M series is under the dash just like a regulator, you can see it behind the battery, it is spot welded to the little 3 X 5" plate there. The primary difference in the two is a regulator can control current output of the generator. As the battery becomes more charged, the regulator reduces the output of the generator.
A cutout is just a small electric on/off switch for lack of a better term. The output of the charging system on an M is controlled by the ignition switch, that is why it has "low" and "high" on the ignition switch. Generators will run like an electric motor if you hook a battery to them. If you did not have a cutout, when you shut the machine off, the battery will try and motor the generator. A cutout "senses" electric flow from the generator, and when none is present it "breaks" the connection between the battery and the generator to prevent discharge. A regulator has this ability as well I should mention.
I remember as a kid walking by our M International tractor. At some time the gen belt had broken and had not gotten replaced yet. As I walked by, I could hear this odd noise. Upon closer inspection, the generator was merrily motoring away because the cutout or regulator had failed and was backfeeding power from the battery to the generator.
As an aside, I now have available electronic cutouts for the M series crawlers and tractors. Significantly more reliable than the old mechanical cutouts, but absolutely ZERO tolerance for reverse polarity and boosting with 12 volts if you happen to do so, so you have to be more careful.
Lavoy

[Stan Disbrow]

Hi,

Ha! I thought you were referring to the fact the third brush generators are different in the case design, for the third brush to stick thru.

Of course, they all have to have a cutout relay to disconnect the generator from the battery when it stops. I have seen plenty stick closed and try to play motor.

Next up, let us discuss the 24 volt starter, 12 volt generator and everything else systems. The ones with two 12v batteries and solenoids to change them from parallel to series for starting, and back to parallel for running.

Then, again, let's *not* talk about those migraine-inducing designs! Ugh!

Stan

[Lavoy]

You know, I have never seen one of them intact, I think everybody gave up on them.
We have a 4020 diesel that is (was) 24 volt. Not as complicated a system as the 1010 used, but still could be a pain in the ass at times. Finally put a complete 12 volt conversion kit on it several years ago, and no more problems.
Lavoy