have often wondered, whu are older 8n's positive ground and some early trucks and cars negative ground, some engineer must have thought there was a benefit to positive ground then decided no there is more benefit to negative ground. could someone give me a little history on why these decisions were made when they were made. thanx in advance.
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Bruce (VA)
Well-known Member
" some engineer must have thought there was a benefit to positive ground then decided no there is more benefit to negative ground."
That's pretty much it.
The detail can fill textbooks; this is the basis of the theory:
http://en.wikipedia.org/wiki/Thermionic_emission
And, it wasn't just tractors; cars & trucks went back & forth too. Check out the chart at the link.
Ground Chart
That's pretty much it.
The detail can fill textbooks; this is the basis of the theory:
http://en.wikipedia.org/wiki/Thermionic_emission
And, it wasn't just tractors; cars & trucks went back & forth too. Check out the chart at the link.
Ground Chart
rustyfarmall
Well-known Member
The natural flow of electricity is FROM negative TO positive. Anyone who has done electrolysis has proven that theory to be true, so actually the old positive ground systems make more sense because those systems do follow the laws of nature.
The REAL question is "Why the change to negative ground"?
Here are a couple of takes: ( not ALL factual, just part)
1) Model T Ford had it right with Negative ground, then Ford "fixed" it with the Model A (Pos gnd), then Ford "fixed" it again in 1956 (back to Neg Gnd).
2) Ford was almost ready to go into production with the Model A & discovered that spark was positive...investigation revealed that the coil was manufactured wrong! Henry, being the frugal man that he was, said," take too much time & money to scrap/re-manufacturer all those coils...just reverse the battery cables". Finally fixed that mistake in 1956.
3) Had it wrong with Model T, fixed it with Model A, then made it wrong again in 1956.
4) Had it right with the Model T, messed it up with the Model A, couldn't admit mistake until all the guilty players were dead & then fixed it in 1956.
5) When lightening strikes, it is an electrical discharge from a Negative cloud to a Positive Earth, so if it was good enough for God, then it was good enough for machines. Of course the main current is in the return discharge from Earth to cloud…but the Earth is still the Positive end of it.
And FINALLY,
5) It doesn't make any difference, like left/right hand threads on lug nuts, as long as user knows how it is set up, either work just fine. It is just a convention necessary to facilitate communication.
the bottom line here is electricity could care less - as long as it has a path to follow it'll be as happy as a tornado in a trailer park. :lol:
DollarBill
Member
As already stated one system is no better or worse then the other. Once semi-conductors came into mainstream use - especially transistors - a standard needed to be chosen. Thus the reason why most standard equipment is negative ground and most electronic accessories are made for negative ground.
t applied at the spark plug electrode. Center is hotter than side electrode, so you want center negative, which is a function of coil winding design/connection. Particular to the N front mount coils, you can't easily reverse the primary connections, as you can on side mount Ns, so you are stuck with Positive ground battery connections IF you want a negative spark. It is of virtually Zero concern.
Many engines were designed and run perfectly well with either or both pos & neg spark polarities. For example, early Harley Davidson engines use one polarity for one cylinder & the opposite for the other cylinder. The Farmall with E4A magneto fires 2 cylinders pos and 2 cylinders negative as do the Ford 2Ns with the Fairbanks-Morse type FM magneto. The Ford 4.6 V6 engine and several GM engines also operate with some cylinders firing Pos & some firing Neg. All in all it is virtually insignificant, but I for one have no objection to anyone optimizing every little aspect possible, just don't expect to see any difference in performance or to see some performance problem to disappear as a result of reversing polarity.
pixie........electrons (-) seek positive (+), its the same the world over. Until the advent/discovery of transistors, (NPN & PNP) it didn't really matter too much ...but... solid state voltage regulators in 12V alternator DIODES and 12V transistor radios changed the ground requirements to NEGATIVE (-). Why? 'cuz diodes and power transistors used metal ground as HEAT SINK. And surprizingly enuff, until the advent of LED digital TV's, the old fashioned ANALOG TV screens were POSITIVE (+14kv) to attract electrons from the TV GUN emitter. (thermionic ...ie... HEAT emitter) And YES, 6V can have thermionic emissions. Didja know ground can be positive and negative at the same time??? Now wrap yer mind around that .......the well grounded Dell
rustyfarmall
Well-known Member
Negative and positive at the same time? All I know is that IF the charging system works, whether it is negative ground or positive ground, and the battery stays fully charged so that my tractor will start when I need it, that IS a POSITIVE experience, and if it don't start, that is a negative experience. Okay, I think I have a positive grasp of the situation now.
TheOldHokie
Well-known Member
- Location
- Myersville, MD
Simplistically. Current flow is a movement of electrons. Charge is a measure of "how many" electrons occupy a space. If you have a "herd" of 1000 electrons some of them will jump the fence into a herd of 100 electrons if given the chance in order to equalize the charge. That is what happens when your spark plug fires - electrons are jumping from one side of the gap to the other. At the subatomic level electrons are all negatively charged particles. Common DC usage of + and - simply indicates which of two areas holds the bigger herd of electrons. The one with more electrons is + and the other is -.
TOH
Bruce (VA)
Well-known Member
Anonymous-0
Well-known Member
According to an article I read in OLD CARS WEEKLY the engineers thought the battery cables corroded less with positive ground.
The internal fibulation resistance of positrons and the external fibulation vibration keeps the photons moving much faster in negative colliods causing the coil to shift electrons faster in a negative direction. This creates a vortex of nuclei and swirls magnetic forces to create more torque to the PTO when the user has the N in the draft mode, thereby causing the flux capacitor to generate more HP.
Simple, eh? (This only works if it is the original six volt system, however, as the theory of relativity breaks down above eight volts)
Simple, eh? (This only works if it is the original six volt system, however, as the theory of relativity breaks down above eight volts)
bobs old iron
Well-known Member
they better come see my batterys, pos ground,,lol
f you don't KNOW.....punt! The 'green tractor' guys just couldn't decide whether positive or negative ground was the right thing to do, so........they covered all bases & did BOTH!
An engineer with freedom & a clean sheet of paper can be dangerous, though. Didn't turn out to be a winner!
This is true if you have the small muffler bearings but I have been using the oversized muffler bearings and found opposite results . Maybe I should use the reverse flow water pump to keep the internal fibulation resistance equal to or slower than the external fibulation vibrations .
William Fissell
Member
As a card-carrying EE, I am a little startled that themionic emission would be enough of an effect to drive a decision positive vs negative. Are you suggesting that since the mobile charge carriers are negative (electrons) having the spark plug 'hot' be negative and the 'ground' be positive gave a hotter or better spark?
I had wondered whether in part the decision was based on cathodic protection - which would not favor a positive ground system.
http://en.wikipedia.org/wiki/Corrosion#Cathodic_protection
interestign discussion
I had wondered whether in part the decision was based on cathodic protection - which would not favor a positive ground system.
http://en.wikipedia.org/wiki/Corrosion#Cathodic_protection
interestign discussion
ot likely much here that you don't already know, Bill.
There is a reason spark coils are wound the way they are. Positive and negative ground coils are wound in different directions in relationship to each other. Spark coils are wound in such a manner that the high tension connection on the coil goes negative when the distributor points open. This means that the rising potential at the spark plug is negative. Why would one want an operating condition where the rising pulse from the spark coil is negative?
The center electrode in a spark plug runs hotter than its grounded electrode. Since electrons can be striped off of a hot electrode more readily than off of a cold electrode, the center electrode is made the negative electrode. The result of this choice is that the arc across the spark plug electrodes can be initiated at a slightly lower potential when the center electrode is the negative electrode. In this manner, thermionic emission aids in the establishment of the initial discharge. A vehicle will run with either a negative output or a positive output from the coil. Millions have operated with the “incorrect” high tension polarity from the spark coil for many years. So it requires a slightly higher potential to strike the arc when engine is up to temperature- big deal. This polarity reversal occurs when converting to negative ground. After the arc (plasma) has been initiated, the circuitry oscillates and the thermionic emission consideration becomes meaningless for that portion of spark duration.
Conclusion -- The coil will work and your tractor will run no matter what you do. If you want to be sure that you have the slightly more desirable initial negative output then pay close attention to the polarity of the primary connection. The primary terminal marked (-) must connect to the (-) terminal on the battery.
Also, Think about a vacuum tube. The purpose of the heater filament is to heat the cathode (negative source point for the electrons) to increase electron thermal energy/mobility so that they will more easily depart as they are attracted to the Positive plate of the tube. It is physics. A very good analogy is the heating of water such that molecules can leave the liquid body, evaporation.
The next point of confusion: The high voltage provided by the secondary circuit of the coil has absolutely nothing to do with whether the battery is POS or NEG ground. That is determined by the direction of current thru the primary of the coil and by the direction of the physical windings of the wire on the coil's core and the way the primary and secondary wires are connected. We can't change the last two items inside the sealed coil, but the manufacturer can. We can change the current direction by connecting BAT+ to coil + and BAT - to coil -, or BAT+ to coil - and BAT- to coil +, thus causing the High Voltage out to be either NEG or POS as we choose. EXCEPT, EXCEPT in the case of the front mount distributor Ns, where due to the lack of easy access to the coil's points side connection (springy thing), you really do not have this choice. Somebody will say I'm wrong & that you can reverse these connections...yes where there is a will there is a way, but do you want to butcher your tractor? The difference is too minor to loose sleep over. Contrary to the popularly stated "you will lose 20 to 30% (or any number someone pulls out....seems that it increased with each repeating of the story) of the coil's spark energy", you will not lose spark energy. It is ever so slightly easier to initiate the arc when HV is negative, but once arc is initiated, the full energy is still transferred from coil to arc whether positive or negative. Further more, when starting, remember, the plug electrode isn't hot yet and this is exactly when you need the best spark possible (cold start). So, not to worry, it will run just fine either way as millions have for years.
More:
explanation to this question comes from a 1978 Rolls-Royce Enthusiasts' Club service manual.
"...it has been found that cars wired positive earth [ground] tend to suffer from chassis and body corrosion more readily than those wired negative earth. The reason is perfectly simple, since metallic corrosion is an electrolytic process where the anode or positive electrode corrodes sacrificially to the cathode. The phenomenon is made use of in the "Cathodic Protection" of steel-hulled ships and underground pipelines where a less 'noble' or more electro-negative metal such as magnesium or aluminum is allowed to corrode sacrificially to the steel thus inhibiting its corrosion."...
For more information on cathodic protection, please read Roger Alexander's article, An idiots guide to cathodic protection or Chris Gibson's article What is Galvanic Erosion, is it serious and can it be prevented? for metal boat hulls. By 1956, all the North American manufactured cars and trucks, except the Metropolitan, were using negative earth [grounding].
Also:
"In most modern automobiles, the grounding is provided by connecting the body of the car to the negative electrode of the battery, a system called 'negative ground'. In the past some cars had 'positive ground'. Such vehicles were found to suffer worse body corrosion and, sometimes, blocked radiators due to deposition of metal sludge."
>>>>>>>>another of many tales:
1923 Model T was built as 6 volts, negative ground. Still is. Somewhere about the time Ford switched to the Model A (1928) the thinking of engineers was that Negative meant charged with electricity, and if the body of the car was charged, leakage to the earth could occur in rain or snow, or if you parked touching a bush, etc. They also worried about wire wheels, which replaced the old wood spokes, and tire rubber with a high carbon black content, making for more leakage. They used this theory to explain frequent dead batteries, which we now know was mostly due to poor construction of battery cells. So, they switched to positive ground.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
the bottom line here is electricity could care less - as long as it has a path to follow it'll be as happy as a tornado in a trailer park.
TheOldHokie
Well-known Member
- Location
- Myersville, MD
That is the crux of the matter. I hope you don't mind me repeating it with added emphasis - I'm afraid it may get lost on folks struggling to wade through the full story.
TOH
William Fissell
Member
JMOR, TOH:
THAT I agree with 100%. Phew. Thot I'd blown all my
money on college fur nuthin.
Bill
THAT I agree with 100%. Phew. Thot I'd blown all my
money on college fur nuthin.
Bill
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