Positive ground

I don't know why they did this. I have a 52 Plymouth. I am told these Mopar cars in the early years were Positive ground. If I am checking a electrical part, that means I use the negative as the hot, and the positive as the ground. That just doesn't seam right from what I have done all my life where positive is the hot wire. Anyone know why Chrysler products used positive ground? Any tractgors use positive ground? Stan

Lots of tractors used positive ground in the early days.
Vern

Positive ground was quite common in vehicles up until mid 1950's and in tractors up into the 1960's.

Probably a number of reasons. Politics, be different from competitor, or "just because". The primary scientific reason at the time was belief that positive ground had less corrosion of the terminals, but improved wiring has made that a non issue today.

Negative ground became the standard in about 1956 with the majority of manufactures going to 12 volt systems and partly because developers of a new invention called the transistor radio seemed to prefer negative ground.

There is nothing mysterious about positive ground. Positive and negative ground is like right hand and left hand threads on a bolt. With bolts the nuts screw on in opposite directions, with positive and negative ground current flows through the circuit in opposite directions. Some electrical devices are polarity sensitive, meaning that current flows through them in a certain direction such as ignition coils, ammeters, charging systems, and some gauges.

Most polarity sensitive devices can work with either ground configuration provided they are properly connected in the circuit.

Starters turn the same direction regardless of battery polarity.

Positive ground does not seem right to you because manufacturers have not used it in over 50 years.

Yeah , it's a good rule of thumb that if it's 6 volt , it's pos. grnd. White trucks continued with pos grnd way into the '70's ....

A good "rule of thumb" is, if it is an American made vehicle with a six volt system, chances are it is positive ground, no matter what make it is. I say American made because some imports, Volkswagen being one, used a six volt negative ground. And as already mentioned, when manufacturers went to twelve volt systems they went to negative ground.

Dalex, I overlooked your comment before I spoke, didn't mean to hijack your comment.

IIRC, Chevy 6 volt was always neg gnd. At least from 36 on. Not sure when, but some GM brands changed to neg gnd & 12 volt before 55. Everybody else used pos gnd. Volkswagen was still 6 volt, pos gnd in 61, not sure when they changed.
Henry Ford & Thomas Edison were close friends & shared ideas. They thought, right or wrong, that pos gnd caused less body/frame corrosion.
The Dodge brothers had worked for Ford, so when they started on their own they kept that system. When they joined with Walter Chrysler, they continued pos gnd.
In the early 50's transister radios were being developed, & by nature of the beast they had to be neg gnd. They can be built with internal connections for the second side of the circuit, but then must have insulated chassis/case. By coincidence engineers were developing 12 volt useage at the same time, so they made the switch to accept the new fangled components.
GM switched their remainingt 6 volt to 12 volt in 55, keeping neg gnd. Ford, Chrysler, & some others made the switch to 12 volt, neg gnd in 56. IHC trucks switched to 12 volt in 57, keeping pos gnd, (learned that one the hard way) then neg gnd in 58.
Most farm tractors kept pos gnd until changing from generators to alternators, which were more economical to build with neg gnd.
More than you wanted to know. Edison pushed use of DC current for the grid to serve power to buildings, even building a system in New York City. Worked great up to 2 or 3 miles from the generator station, but due to line loss, not useful over longer distance. The last I heard, there are still a few buildings in lower Manhatten using the Edison DC power generators.
At the same time, Tesla was developing AC current.His system at Buffalo could transmit power much longer distances, with minimum line loss, & became the standard useage.
Willie

Most tractors switched to negative ground when they switched to 12 volts. My Oliver 550 diesel is an exception- 12 volt positive ground.

Most everything 6 volt was positive ground up until the 50's. GM being the odd man out with always being negative ground, even on 6 volt. My Super 55 is 12v positive ground.

All of the Olivers with generators were positive ground,including the 12 volt ones.

Freightliner and some of the other companys didn't switch over to negative ground till the late 1970s or early 80s on their trucks.
In the early 70s it was difficult to find a CB radio that would wyrk with a positive ground truck.

I really struggled in power mechanics class, teacher kept talking about all the negative ground stuff..... Never had worked on a negative ground farm machine, everything dad had was positive ground.

Paul

JohnDeere AR, 12 volt positive ground. I eventually had to mark that on the battery box as I could never remember when installing the battery. Currently working on the 39 Ford sedan which, like all old Fords, is six volt positive ground.

Funny thing, the Model T Ford had NEGATIVE ground, the Ford went to POSITIVE ground until 1956, then changed back to NEGATIVE ground. Go figure!

"GM being the odd man out with always being negative ground, even on 6 volt."

You are forgetting Cadillac is part of GM and they were (+) ground from the start, up into the 40"s!

The SC Case was 6V negative when other tractors of that era were positive. Go figure!

(quoted from post at 00:15:04 09/04/14) I don't know why they did this. I have a 52 Plymouth. I am told these Mopar cars in the early years were Positive ground. If I am checking a electrical part, that means I use the negative as the hot, and the positive as the ground. That just doesn't seam right from what I have done all my life where positive is the hot wire. Anyone know why Chrysler products used positive ground? Any tractgors use positive ground? Stan

Click to expand...

While nobody knows how the term" ground" came to be used for the chassis of mobile machinery is a mystery. I suppose it's shorter to say than " chassis" or " chassis return".
The term ground confuses Bubba on AC electrical equipment. Sooner or later Bubba will try to run neutral current through the bare ground system instead of the insulated white wire.

(quoted from post at 12:28:24 09/04/14)

(quoted from post at 00:15:04 09/04/14) I don't know why they did this. I have a 52 Plymouth. I am told these Mopar cars in the early years were Positive ground. If I am checking a electrical part, that means I use the negative as the hot, and the positive as the ground. That just doesn't seam right from what I have done all my life where positive is the hot wire. Anyone know why Chrysler products used positive ground? Any tractgors use positive ground? Stan

Click to expand...

While nobody knows how the term" ground" came to be used for the chassis of mobile machinery is a mystery. I suppose it's shorter to say than " chassis" or " chassis return".
The term ground confuses Bubba on AC electrical equipment. Sooner or later Bubba will try to run neutral current through the bare ground system instead of the insulated white wire.

Click to expand...

in't it the truth! Some Bubbas can't tell the difference between a car/truck/house/factory/AC/DC or a well from a hole in the 'ground'.
Me, well I think ground is: