1948 JD Model D 12volt ground

Does it have a positive ground? Have a good day guys!

that would have a generator, which means positive ground.
Tim

You actually have a choice. If you want negative ground, all you have to do is switch the bat terminals, polarize the generator, switch the wires on the coil and ammeter --et voila! Lights and starter don't care. HTH

Generator doesn't mean positive ground. They will charge either way.
Your tractor is positive ground though.

That's funny, I thought it was a John Deere we were talking about. Not a Chevy. My mistake.

ALLLLLLLL 6 and 12 volt JD Two Cylinder Tractors were originally POSITIVE GROUND. IE the POS battery post was wired to chassis ground. The Generator, however, can charge at EITHER + OR - ground.

ON JD 24 volt Tractors, the 24 volt Generators and Starters WERE ELECTRICALLY ISOLATED from chassis ground. As a result they WERE NOT NEGATIVE OR POSITIVE GROUND. When the starter relay or VR cutout relay was closed so those 24 volt devices could operate, one brush was effectively connected to an UNGROUNDED POS BATTERY POST while another brush was effectively connected to an UNGROUNDED NEG BATTERY POST (24 volts). But neither are connected to ground. Again the electricals on the 24 volt starter and
24 volt Generator ARE NOT GROUNDED (To Pos or Neg)


HOWEVER if it had two 12 volt (or 4 sixes) batteries in series, at the mid center tie point where the 2 join, THAT IS WIRED TO FRAME GROUND. However, the outer two untied terminals + one battery and and - of another, thats 24 volts (for starter and genny) are NEITHER ONE GROUNDED IE the 24 volt portion IS NOT GROUNDED.

Hope this helps clear up some of the 24 volt system recent misunderstanding as well as all 6 and 12 volt Two Cylinder Deers were POSITIVE GROUND

Any questions?

Hope this helps, God Bless all here

John T Retired Electrical Engineer

Thanks for your thoughts Tom, so good to hear from you and I know youre trying to help, as you said, youre indeed a kind gentleman I AGREE and youre a good friend.

HOWEVER I"m afraid youre mis leading some of the people here ESPECIALLY the non electrical trained lay persons and even if you spoke with the Electrical Engineering department at some university. (bet it wasnt Purdue University, thats NOT how they trained me)

YES all other JD two cylinder tractors 6 and 12 volt HAD THE POSITIVE BATTERY TERMINAL WIRED TO THE FRAME GROUND and thats why they were called POSITIVE GROUND. One of the battery posts, Pos or Neg, is tied to frame ground on those tractors

HOWEVER on the 24 volt system NEITHER OF THE OUTER UNTIED BATTERY TERMINALS + OR - ARE WIRED TO FRAME GROUND. The 24 volts which is present from + of one cable and - on the other IS NOT WIRED TO FRAME GROUND and if either were it would short out the battery yikessssssssss

A + or - battery post is NOT in the electrical industry referred to a ground, ITS ONLY if you bond one or the other to a tractor frame its then called POS or NEG ground. The 24 volts is ONLY post to post NOT either post to an unattached tractor frame ground......

On the 24 volt NEITHER of the outer untied battery posts are tied to frame ground,,,,,,The windings on the starter and genny (unlike on 6 or 12 volt) ARE NOT TIED TO FRAME GROUND,,,,,,,,Neither of the brushes (unlike on a 6/12 volt) ARE TIED TO FRAME GROUND.

SO THE 24 VOLT PORTION IS NOTTTTTTTTTTT POS OR NEG GROUND

Tom, do NOT feel bad if you dont get this, you claim your background is as a History professor and auto mechanics instructor, mine is an Electrical Engineer and my explanation agrees with the John Deere design and all their diagrams AND NO JD 24 VOLT DESIGNS OR DIAGRAMS SHOW THE 24 VOLT POSITIVE (or NEG for that matter) )TIED TO FRAME GROUND. However, the 6/12 volt diagrams DO SHOW THE POS TO FRAME GROUND and guess what!! They are called POS GROUND.

Can you show me a Deere drawing showing on the 24 volt side (outer untied 24 volt posts) EITHER Pos or NEG having a tie to FRAME GROUND????

So as a good friend we must agree to disagree Tom, until you can show a diagram to the contrary showing the starter or genny or its windings tied (either POS or NEG) to frame ground youre wrong calling the 24 volt POSITIVE GROUNDED and Im right lol. Please understand,,,,,,,,,,,the 24 volt starter and genny are NOT TIED TO FRAME GROUND (Neither the Pos or Neg) THEY ARE NOT POSITIVE GROUNDED

Hey Ive also made mistakes before but manned up and admitted it grrrrrrrr its no fun to eat crow is it? and we allllllllllll make mistakes so dont feel bad or dont take offense, Im only trying to help here NOT fight.

If Im wrong and the 24 volt IS POSITIVE GROUNDED TO FRAME I will kindly apologize IT WONT BE THE FIRST TIME EITHER GRRRRRRRR

May God Bless you Tom, hang in there and help out when you can, we could all use a little help now n then. I"m glad youre no longer banned or barred as you once stated you were

Best wishes

Your friend John T

(quoted from post at 08:57:45 10/02/13) The 24 Volt System is POSITIVE GROUND just like all other John Deere tractors before the introduction of alternators in the 1969 models. If we define ground as the point of 0 potential, then ground is either the positive battery terminal with the tractor stopped, or the positive brush of the generator with the tractor running.

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Barack
If you believe the JD 24 volt system is positive ground as you keep stating I hope you backed up to receive your compensation(PAY CHECK) when you gave your seminar at the Gathering of the Green because you are WRONG. It's positive(+) & negative(-) not just positive to divide the two 12 volt circuits. Due to your incorrect statement about a JD 24 volt system being positive ground(ONLY) I going to have retract your award as "head of the class" and move you to the bottom. :wink:

If you think you're correct and I'm incorrect please feel free to explain the 2 ground straps(parts key 21 & 22) that attach to trans case.

How does the 24V argument have anything to do with a 12V D?

(quoted from post at 19:24:10 10/02/13) How does the 24V argument have anything to do with a 12V D?

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D-
As you and many others know there's no "ground" correlation between 6/12 volt systems & JD 24 volt systems but Barack keeps trying to convince himself that there's a correlation.

Right on Bob, those devices still work and dont really care which battery post happens to be tied to a huge hunk of rusty old iron lol

Once the Genny is polarized so its residual field pole magnetism matches the battery polarity for initial start up charging and the coil and ammeter are correct ITS OFF TO THE RACES

John T

Jim, I thought we had the JD 24-volt system throughly discussed a couple of days ago. But seems this subject keeps appearing. Don't know why this 24-volt system is so difficult for some to understand. Al

You're wrong Barack, since you are so certain of yourself, find either the + or - on any tractor that is truly connected to the earth, true ground. Everthing else is either a postive wire or negative wire. The biggest wire on my 4020 diesel is both positive potential and negative potential. Seems that being a long time auto tech instructor and college professor and your college professor buddy has made the both of you the absolute authority on the 4020 diesel? I have seen John T's comments spot on, helping people with there electrical problems all I have seen out of you is continual argument. Guess Who I have respect for?

(quoted from post at 22:48:57 10/02/13) It is a shame that some have so much trouble with it, even though the concepts have been explained to them many times. For the slow learners, I recommend they come to my class at Davenport, Iowa in March or at least read my article in the April issue of Green Magazine.

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Barack
You are the slow learner. Why would anyone want to waste their time going to a class that the INSTRUCTOR is stating WRONG information!!!!!!!!!!!! Reading your article would probably be just as misleading.

Please explain the parts schematic I posted earlier of the batteries of a 4010 diesel with 24 volts that one battery has a (+) positive connection to trans case and the other battery has a (-) negative connection to trans case. You must think JD engineers were wrong and you think you're correct.
Jim