Generator Third brush Adjustment

[Karl]

I am replacing the generator in my car with a more original generator.
However I can't identify the third brush to adjust output. All the Brushes are spring loaded and rock back and forth but none move up or down . Help !

[petehoovie]

Were you able to count three brushes? With the generator mounted and the cover removed, the third brush will be visible toward the top of the armature somewhere between 9 and 11 o'clock. It should move from about 9 o'clock to 11 o'clock as viewed from the rear of the generator....

[Floyd]

In looking at the pics, the one easily seen in the photo is the 3rd brush. It rotates about the centerline of the armature. With a wooden dowel or just a stick, push against the post in the pic. It should move in both directions, ( "up and down It takes a little bit of force to move it. You are on your way.
just an opinion

[koates]

Hi there, as stated by Pete the third brush is near the top of the generator with gen mounted on the V8 engine. Also the third brush is normally somewhat thinner in cross section (thickness) than the other two brushes. The brush will rotate around the circumference of the commutator by pushing on the brush holder post and not on the brush itself. Sometimes they are tight and a LITTLE tap is required. Move brush with generator rotation to increase charge amps and against rotation to reduce charge amps. Maximum safe amps setting for a 1934 generator is 14 amps but for normal daytime driving this is way to high. About 5 amps showing on your dash ammeter when running in daytime (no lights on) is plenty high enough. Remember this 5 amps showing on the ammeter is actually a generator output of around 8 amps allowing for the ignition coil current draw. This setting will not cover all the current draw of your headlights so if doing much night driving (say more than an hour) the brush would have to go up to 14 amps. If left at i4 amps in daytime with lights off then the battery will be overcharged. A "FUN PROJECTS" brand round voltage regulator which replaces the original cut out on top of the generator will overcome this drawback. You must order for POS or NEG ground regulator to suit your electrical system. Regards, Kevin.

[Ian NZ]

Adjusting the third brush which is on top of the generator opposite the oil cap with the dash ammeter is not a good idea, it should be adjusted separately or by an auto electrician on a their machine to 10 amps. I have fitted a " Fun projects" regulator which works very well on my 32 generator and set it at no more than 14 amps on the dash ammeter as they recommend, and I have found the generator was getting extremely hot, and I have just about burnt it out, because those 32 generators do not have any fan blades on the pulley and there are no vents in the casting on front of the generator, so at the moment it is at the auto electrician being set a 10 amps as I do not do much night driving anyway.

[MGG]

Sponsored Links (Register now to hide all advertisements)

I set the third brush on my 1934 generator, also equipped with a Fun Projects regulator, to the letter of their instructions. I have a good battery (6-volt) re-built generator, and a very accurate ammeter also from Fun Projects. After starting the engine, the generator will put out about 6-7 amps as it is replacing the battery starting charge. After about 5 minutes the charge is replaced and the generator charging rate decreases to a steady 2 amps. If I turn on the headlights, the regulator allows the charge rate to go up accordingly so the generator is still putting back about 2 amps +/-. This charge rate should never cause a problem for the generator or battery.

[fourfords]

I'm surprised no one volunteered exactly HOW to adjust the third brush. Standing on the drivers side of the car, remove the band around the generator. I take a small wooden dowel and gently tap the third brush DOWN a bit to raise the voltage output. Gently tap it up to decrease the voltage. If you have a six volt system with no other accessories, and after you make your estimated adjustment, start your car and look at the ammeter. When it is flat at zero when you have your headlights on, you are Good to go. Don't forget to apply a couple drops of oil to the oil ports on the top front and rear of the generator every once in a while.

[koates]

fourfords, Im not sure but Karls ford might be a right hand drive car being in NZ. So therefore your drivers side up/down instruction on the third brush would be arse about would it not ? The ford owners handbook and service manuals always say to adjust the third brush with rotation of gen to increase output and against rotation to decrease charge rate. Also back in the day and even today most people don't own a proper automotive generator test set with a quality amp gauge and voltmeter to connect to the generator to set the third brush. Nor do they have access to an auto electrical repair shop with a test bench. The best they can do is use the dash ammeter which only gives an approximate reading but is usually good enough. Also the 32 and 33 ford V8 generators had no cooling openings in the front or back of the generator and no cast in fan blades on the gen pulley so a maximum charge rate of 10 amps is all they can safely charge. The 34 ford V8 was the first year of the air cooled generators which had a safe output of 14 amps. They will do more amps but 14amps is a SAFE maximum with no overheating. Regards, Kevin.

[petehoovie]

This, from Supereal as posted on the EFV8 Club site
-- 04-11-2010 @ 10:36 AM

"You can adjust the generator by placing a voltmeter across the battery posts, and set the 3rd brush to show just above 7.5 volts at a fast idle. If you drive at night, which most of us don't, adjust with the lights on. Otherwise, leave them off. Most ammeters are like a weathervane. It shows the direction of the flow, but not velocity (current). As for polorizing, it isn't always necessary. If the generator has output, you don't need to do it."

[Brian]

I love three brush generators; they are so simple. However, the concept seems to freak people out these days. Tighten up the cover band sufficiently that it will stay in place, but can slide back to reveal the cutouts in gene case. Then, when darkness is approaching, and you're still out on the road, it is easy to pull off the road, open hood, slide back cover, move brush down, slide cover back, close hood, and carry on driving. Takes longer for me to type it than to perform it. You don't even need to switch off the engine!

Once you become familiar with the two positions you'll need to position the brush, you'll be able to do it blindfolded!

[Ian NZ]

As the three brush generator on my 1932 has a mount on the back to the manifold I cannot remove the back cover, I used to have a short bit of an artists wooden brush and insert it into the holes number 1 & 2 on the back cover to rest against the brush holder to move it for more charge on hole 1 and less charge on hole 2. The photo shows the large wooden brush on hole 1 on the generator removed from the car.

[koates]

petehoovie, I do not agree with your volt meter method of adjusting the third brush and neither does the ford shop manuals. The third brush system has no voltage control as such and even if you set it at 7.5 volts at the battery you still don't know what the amps are doing. If it is a two brush gen with a separate voltage and current control regulator then you set the voltage and current outputs with the regulator. Correct way to set the third brush type is by using an ammeter and limit the generators safe maximum amps output to the recommendation OR LOWER as required by your vehicles loads. Being doing it this way for more than 50 years Pete. Just make sure the amps charging don't exceed the generators safe maximum at any time. Regards, Kevin.

[petehoovie]

Originally Posted by koates

petehoovie, I do not agree with your volt meter method of adjusting the third brush and neither does the ford shop manuals. The third brush system has no voltage control as such and even if you set it at 7.5 volts at the battery you still don't know what the amps are doing. If it is a two brush gen with a separate voltage and current control regulator then you set the voltage and current outputs with the regulator. Correct way to set the third brush type is by using an ammeter and limit the generators safe maximum amps output to the recommendation OR LOWER as required by your vehicles loads. Being doing it this way for more than 50 years Pete. Just make sure the amps charging don't exceed the generators safe maximum at any time. Regards, Kevin.

@koates - Re-read my post. I quoted 'supereal's' method...

[Karl]

Thanks to all replies . I found the the third brush it was just so gummed up on the plate that it wouldn't move- it does now . My car being an early 34 and an export model is fitted with the early post generator with no cooling fins (ie 1933) I have an oval cutout which John Reagan aka FunProjects has altered for me -as my car has a radio I believe this cutout is correct. Of course to fit it I need the later 2 wire generator which I suspect is a better generator to use as Ian has eluded to with less chance of over heating. I will keep all the original bits to reinstall so I can take it back to stock if desired . There seem to be quite a few early 1934 differences! Also I suspect overseas cars used up the last of the previous models parts -Karl

[Capt Kirk]

Reviving an old thread. I may be having a similar situation as has been discussed above. I just checked voltage at the cutout. It's 7.5 at idle and goes to 9 with the engine spooled up. My amp gauge shows positive charge at idle but it's near the 0 line. When driving, it stays at 10 amps charging. It's a 3 brush generator with a Ford Script cutout from Macs (10 years old by now). I also have an Optima installed on its side. As I read the above thread, I'm getting some mixed messages so I have to employ some reasoning.
It seems to me that the cutout is designed to interrupt the generator when battery voltage is at whatever the voltage setting of the cutout is...correct? If the cutout interrupts the generator then doesn't the amp gauge read only whatever electrical load there is on the car? Engine, lights...etc? Wouldn't the amp gauge read negative in this case? Then, when the battery voltage gets low enough, wouldn't the cutout bring the generator back on line and the cycle starts all over again?? I'm wondering if my cutout is bad because the generator seems to be doing its job.

As a matter of future reference and off topic...I wasn't sure if I should revive this thread or start a new one on the same topic. What is forum policy on this? kirk

[VeryTangled]

Originally Posted by Capt Kirk

As a matter of future reference and off topic...I wasn't sure if I should revive this thread or start a new one on the same topic. What is forum policy on this? kirk

I like to see things stay in one thread, makes it easier for me to stay on topic.

[fourfords]

Hi Koates, I think you're right about the right hand drive. I didn't look close enough at the origin of the post. I hope I didn't screw him up too badly!!

[J Witt]

As a child, on family trips from Savannah to Chattanoga we would see cars (ours too) on US 41 running with the lights on too avoid the dreaded boiling battery from overcharging.

This was in the late 40's to early 50's when my dad was stationed at Hunter AFB and most of the relatives lived in Chattanooga. We sometimes rode the dog when the family car wasn't reliable enough for the trip.

John

[Jeff/Illinois]

karl, get Tom Wesenberg's Electronic Voltage Regulator and change it out for your third brush.

I swear by it, we have one in our '36 pickup and it works GREAT makes the gennie a lot more reliable, keeps the battery charged better w/o cooking out the electrolyte from overcharging.

I wouldn't be without it anymore. Tom is active on the Model A side you can PM him here just type in 'Tom Wesenberg'.

[JSeery]

Originally Posted by Capt Kirk

I just checked voltage at the cutout. It's 7.5 at idle and goes to 9 with the engine spooled up. My amp gauge shows positive charge at idle but it's near the 0 line. When driving, it stays at 10 amps charging.

I would get something fixed to correct this condition as quickly as possible, it is bound to damage the battery charging it at 9 volts. It will take a toll on the rest of the car as well, lights etc.

One way to go is an electronic cutout, but I would start by backing the charge rate on the generator down. There is no reason to be running it at this level. 10 amps (ever if it's a guess with the stock gauge) is way to much, should be right at 0 on the charge side slightly.

[Capt Kirk]

I kinda though this might happen in reviving an old thread. Karl's last post was in April and I'm guessing he got his problem solved. I will send tom a PM. Kirk

[Capt Kirk]

Thanks JSeery...I don't drive the car much but I know what you're saying and I was worried about it too. Funny (but not so much) you should mention the lights. I don't have headlights anymore as of recently. Guess I'll be shopping for some bulbs soon too. Should I be talking with Tom regarding a new cutout?

[Brian]

Modern electronic solution to a perceived problem! Running during the day with headlights on? w/o cooking out the electrolyte from overcharging?
The problem is NOT the generating system. It is the owner/operators lack of understanding of how the system works.
It's an old Ford. Things are simple; during the day, whilst toddling down the road, all the battery needs to supply is sufficient current to feed ignition; what else is there? Accordingly, all the generator needs to supply is sufficient current to compensate; 2 amps?
Come nite time, lights are on, current demand off battery is more [ ignition plus lites] so the generator output must be increased to suit. Move the 3rd brush down. Look at the ammeter. That's why it's there. you want to have it showing the same 2-3 amp charge with headlights on.
You are the regulator of current output by moving the third brush to suit the load on the battery. Sigh.

[ford38v8]

Originally Posted by JSeery

I would get something fixed to correct this condition as quickly as possible, it is bound to damage the battery charging it at 9 volts. It will take a toll on the rest of the car as well, lights etc.

One way to go is an electronic cutout, but I would start by backing the charge rate on the generator down. There is no reason to be running it at this level. 10 amps (ever if it's a guess with the stock gauge) is way to much, should be right at 0 on the charge side slightly.

I agree, but will add one detail: When you start the engine, you draw the battery down a bit, especially if it takes more than a couple of cranks. Your ammeter will show a couple points into the charge till you've driven sufficiently to recharge, at which time the needle will fall back to normal. If this recharge process takes more than 15 minutes, you may have a problem.

[Capt Kirk]

Originally Posted by Brian

Modern electronic solution to a perceived problem! Running during the day with headlights on? w/o cooking out the electrolyte from overcharging?
The problem is NOT the generating system. It is the owner/operators lack of understanding of how the system works.
It's an old Ford. Things are simple; during the day, whilst toddling down the road, all the battery needs to supply is sufficient current to feed ignition; what else is there? Accordingly, all the generator needs to supply is sufficient current to compensate; 2 amps?
Come nite time, lights are on, current demand off battery is more [ ignition plus lites] so the generator output must be increased to suit. Move the 3rd brush down. Look at the ammeter. That's why it's there. you want to have it showing the same 2-3 amp charge with headlights on.
You are the regulator of current output by moving the third brush to suit the load on the battery. Sigh.

I agree with most of what you're saying about demand and what-not but I don't believe that someone's grandma popped the hood, removed the band and slid the 3rd brush if she got caught by nightfall shopping at the Alpha Beta store. I guess the third brush regulates current but if the cut-out fails, the 10 amps of current is going to the battery whether it needs it or not...right?

[Brian]

Sponsored Links (Register now to hide all advertisements)

If the cutout fails, it sticks shut, and the ammeter will record a massive discharge upon turning engine off. I bet our grandparents understood what it took to operate a vehicle in their day.
The cut out is exactly that; a cut out; it prevents backflow of current, much the same as a modern day diode. It has squiddly dot to do with regulation of generator output.

[Capt Kirk]

Originally Posted by ford38v8

I agree, but will add one detail: When you start the engine, you draw the battery down a bit, especially if it takes more than a couple of cranks. Your ammeter will show a couple points into the charge till you've driven sufficiently to recharge, at which time the needle will fall back to normal. If this recharge process takes more than 15 minutes, you may have a problem.

I've got a problem then. When cold, it cranks 1 to 2 revolutions before firing. At idle, it's slightly above the zero line (positive charge). Yesterday, it read 10 amps at road speed for the entire drive. I'm assuming my cutout is bad. Yesterday, I drove maybe 15 minutes to a friends house and turned the car off. 15 minutes later, it cranked hard but started. As I run all this through my mind, maybe the Optima was getting 10 amps that it didn't need for those 15 minutes and heated up to the point where a restart when hot was lacking.

[Brian]

So...was the battery hot [boiling]? Sounds to me like you've got a different issue.

[Capt Kirk]

Originally Posted by Brian

So...was the battery hot [boiling]? Sounds to me like you've got a different issue.

It's under the floor and it's an Optima so I don't think it boils per se but I'm sure it can get too hot from over charge.

[JSeery]

Why not back the charge rate back on the generator? Fairly quick and simple!

[ford38v8]

Originally Posted by Capt Kirk

I've got a problem then. When cold, it cranks 1 to 2 revolutions before firing. At idle, it's slightly above the zero line (positive charge). Yesterday, it read 10 amps at road speed for the entire drive. I'm assuming my cutout is bad. Yesterday, I drove maybe 15 minutes to a friends house and turned the car off. 15 minutes later, it cranked hard but started. As I run all this through my mind, maybe the Optima was getting 10 amps that it didn't need for those 15 minutes and heated up to the point where a restart when hot was lacking.

As Brian said, a cutout is simply a one way valve, and regulates not at all. A Fun Projects cut-out is actually an electronic regulator which looks like a period correct cutout. Your zero reading at idle may indicate a generator speed too slow to begin a charge. Your burned out lights may also have been the canary in the mineshaft that you didn't recognize.

[FlatheadTed]

I think it would take the 15 min to recover the OP charge level from starting ,so no over charge ,Use a quality jump cables and run a additnal ground to the back of the starter from the battery

[Capt Kirk]

Originally Posted by Brian

If the cutout fails, it sticks shut, and the ammeter will record a massive discharge upon turning engine off. I bet our grandparents understood what it took to operate a vehicle in their day.
The cut out is exactly that; a cut out; it prevents backflow of current, much the same as a modern day diode. It has squiddly dot to do with regulation of generator output.

Brian, Aren't these cutouts a fairly simple "switch" that essentially tells the generator to stop charging? My generator is charging...too much. Seems to me that it's the job of the regulator (cutout) to figure out what's required under the circumstances. When I've got only engine load on the electrical system and it's charging 10 amps then I think there's something wrong. Sure, I could move the 3rd brush to handle the couple amps required to run the engine but as soon as I fire up the big bass woofers and the 500w amp...the generator isn't going to cut the mustard. My reasoning is based on a battery charger...you can set these to 2 amps, 15 amps...50 amps....at the same voltage. Apparently, my generator is set at 10 amps and that's fine. Battery chargers will reduce the amperage the closer the battery comes to fully charged. A charger likely does this through some modern day regulator. My generator is putting out the amps and the volts...only thing left is regulation of those...I'm guessing.

[Capt Kirk]

Jseery....pm sent

[Brian]

big bass woofers and the 500w amp...the generator isn't going to cut the mustard.
So... you're running 12 volt with a heavy demand on the charging circuit?
Not 6 volt stock?
The regulator is not the cutout. The cutout comprises part of a regulator , along with voltage and current controls.
A 3 brush generator only incorporates a cutout. YOU, via the third brush, regulate the output of generator.

[Capt Kirk]

Brian...I was joking to make a point. The car in question is my avatar. The only music in that car is playing in my head and likely taking necessary amps from other physical motor functions

[JSeery]

Originally Posted by Capt Kirk

Jseery....pm sent

If you sent a PM it didn't come through. Think you are confusing yourself on what is going on here. Your generator is not set properly and the cutout is not going to correct that. Get the generator set properly, very simple to do and if you don't like the new setting move it back. The cutout is a cutout, not a regulator. It works properly when the generator is set properly, it goes not correct for it.

[Capt Kirk]

If the only function of the cutout is to prevent backflow of current after the car is shut off and turning the generator into a motor...then I had things completely screwed up in my mind. I can accept and understand that but I guess I figured things differently. I don't ever remember my dad stopping during out long cross country road trip vacations telling us that he needed to move the third brush because it was getting dark. I was raised up in this car...Hell, I may have even been conceived in it...who knows?

[JSeery]

I'm not a fan of moving it around everyday, but it does need to be set correctly at least once!! You are frying you car parts and battery and all you need to do is set it correctly. No need to mind game this one as it is so easy to perform a real life experiment and see how it works in real time.

[Capt Kirk]

Originally Posted by JSeery

If you sent a PM it didn't come through. Think you are confusing yourself on what is going on here. Your generator is not set properly and the cutout is not going to correct that. Get the generator set properly, very simple to do and if you don't like the new setting move it back. The cutout is a cutout, not a regulator. It works properly when the generator is set properly, it goes not correct for it.

I will go out and set it now. I incorrectly assumed that it was an automatic "on off" switch based on the batteries needs. Now I understand that I can set the third brush to put out a constant amperage based on my driving needs. I don't drive it at night and something has changed with the way it's charging over the years. I will report back in a bit after I make the change.

[Brian]

Maybe your Dad didn't understand the concept either, same as all those people driving with their lights on to 'correct' an overcharge situation. Again, YOU regulate the output to suit the load requirements of the generator. You do this by moving the third brush and referring to the ammeter. After a while, it becomes so familiar, you'll just do it autocratically.
As I stated in an earlier post, just set the tension on the coverband sufficient to allow it to be slipped forward and backward and stay in place.
edit; sorry to repeat myself, it appears you've got it sorted.

[JSeery]

Originally Posted by Capt Kirk

I will go out and set it now. I incorrectly assumed that it was an automatic "on off" switch based on the batteries needs. Now I understand that I can set the third brush to put out a constant amperage based on my driving needs. I don't drive it at night and something has changed with the way it's charging over the years. I will report back in a bit after I make the change.

Just sent you a PM

[Bob C]

This might help explain how your generator works.

THREE BRUSH GENERATOR OPERATION:
The three brush generator design required removing the cover and adjusting the position of the third brush in order to change the charging rate.By moving the position of the third brush the voltage applied to the field windings was changed. This in turn changed the strength of the magnetic field applied to the rotating armature and thus set (or limited) the maximum charging rate, or current output, of the generator. The generator would continue to charge at this fixed current rate all the time, regardless if the battery was boiling over or dead, lights on or off, it didn’t matter. This was fine if the electrical load on the system remained constant, but loads usually do not. If the battery was low, or additional loads such as lights were turned on, the generator output remained the same. In short, the 3 brush generator cannot automatically compensate for any type of varying electrical loads.
The 3 brush generator did not have any type of voltage regulator built into it. Adjusting the 3rd brush only changed the current output of the generator. The battery essentially became the voltage regulator in the system. As a result, the generator consistently applied an excessively high voltage to the battery (on the order of 8 – 8.5 volts). In fact, as the battery reached a fully charged state, the generator current output actually increased slightly as did the battery voltage! Over prolonged periods, this would cause overcharging of the battery. Many batteries and fine paint jobs have suffered from this poor regulating system!
If for some reason the battery were to be dropped out of the circuit, the generator output voltage would now be unregulated. If allowed to run unregulated, the generator voltage would quickly rise and could easily get up to 40 or 50 volts. This would in turn burn out the light bulbs and other electrical equipment, such as ignition coils. Excessive heat would be generated internally and quickly damaged the generator as well.



Bob

[Capt Kirk]

This is the sound of someone eating crow! I offer my sincerest apologies for my doubting posts and humbly say that you were right!. The band was a little stuck since the paint kinda bonded together. The third brush moved easily...I moved it upward a bit and noticed a difference in the amp gauge...moved it some more and saw an additional decrease in amperage. My lights didn't work yesterday but thought I'd give it another try just now and they work (twilight zone stuff!). I now have it set with the needle a blond fuzz above the centerline at idle and it looks to be at about 3 or 4 amps with the engine spooled up. I turn my parking lights on and it's a hair on the discharge side and when I turn the headlights on at high RPM, it's showing like a 5 amp discharge. I don't plan on driving at night so the lights are irrelevant but if I need some extra amperage, I know where to get it now. Should I adjust it farther so the amp gauge is reading 0 when at high rpm? Again, sorry for my doubting posts...you guys are great!

[Capt Kirk]

Jseery...didn't get yours either

[JSeery]

Sponsored Links (Register now to hide all advertisements)

Just slightly above o on the charging side.

[JSeery]

Originally Posted by Capt Kirk

Jseery...didn't get yours either

I'll just post it here, PM doesn't seem to be working.

"Antique automotive electrical systems do not run on their battery, they run on their generator all the time. EXCEPT when the engine slows down to idle for a stop and then the cutout relay releases and the car runs on the battery. If the ammeter is going up to it's highest position the battery is taking that in as a charge. It should, and will, go away after a few miles as the battery charges up and the remaining amps showing will once again be what the car needs to run. It's like a "Y". The generator at the one end and the car's running load at the other end and the battery at the remaining end. The cutout is in series with the generator end. If it wasn't there then the generator would just keep pumping current into the other end, the battery and the car's load, as required and all would be fine. The only problem is when the engine slows down or is stopped altogether, the battery will try to put it's charged current right back into the generator's windings. Hence the full name of the cutout "Reverse Current Cut Out". It performs no other function but to stop the battery from "seeing" the generator as a dump to ground."

[Brian]

Congratulations! Simple ain't it? You'll have no more troubles now you've got a grasp on it.

[Capt Kirk]

Brian...sorry for doubting you. My dad was a good mechanic and engineer working for Aerojet General in LA. It was the daily driver as he built the family. The fault in my posts was because I was still crapping green in my diapers during those days. This was a 5 minute fix...not counting a beer and engine warm-up.

[koates]

Capt Kirk, I am greatly relieved that, Brian, JSeery and Bob C have been able to finally educate you into the correct workings of the third brush generator system. Had some family health issues the last few days and therefore no time to post anything. You could read my posts # 4, 8 and 12 for earlier answers. The correct name for the generator cut out is a REVERSE CURRENT RELAY or RCR. Just another point, depending on your engine idle speed which would be approx. 500 RPM, at that speed the generator would have low voltage output and no output in amps and therefore the cut out contacts would still be open. Engine RPM may have to be 750 or more to enable the generator voltage to be high enough to close the cut out contacts and allow battery charging to be possible. Back in the day when these cars were used every day and most people did not understand the charging requirements one had to take their car to the dealership to have the third brush adjusted down or up to cover summer or winter conditions. The owners handbooks stated this. Good luck with your nice 1936 Ford V8. Regards, Kevin.

[Bob Carabbio]

Originally Posted by Capt Kirk

It seems to me that the cutout is designed to interrupt the generator when battery voltage is at whatever the voltage setting of the cutout is...correct?

Nope - the Cutout Couldn't care less about Battery voltage, or electrical system load. It simply Disconnects the generator completely when the generator OUTPUT voltage falls below the battery voltage, and reconnects the generator when the generator output voltage rises ABOVE about 6.2 volts, or so.

The Model "A" generator is "Third brush regulated" to deliver a "CONSTANT AMPERAGE" to the Electrical system of the car Regardless of what the battery voltage, or the generator speed happens to be. It does this because of the "Bending of the magnetic lines" is directly proportional to the rotational speed of the generator at the point where the field excitation is picked off by the "third brush".
When the generator speeds up, the Third brush delivers LESS power to the FIELD COILS. This automatically reduces the Field coil excitation, and keeps the AMPERAGE (not the voltage) delivered to the electrical system relatively constant. The Model "A" generator is only capable of about 10 amps constantly supplied, and will overheat and "throw solder" out of the commutator if you stress it higher.

A "Voltage regulator" is an entirely different breed of cat. It has a "Cutout relay" which functions exactly the same as an "A" cutout, but there are two additional relays which both control the Field Excitation,

The Second relay limits the VOLTAGE that the generator puts out, and is why the Charging rate after a startup will be HIGH, to replenish the energy used by the starter, and then fall to a low value as the battery voltage rises to avoid overcharging the Battery.

The third relay is a Current control, which won't let the generator exceed it's thermal capability, when current draw on the electrical system is high.