+ or - earth

ESSX28-1

When did Hudson change to positive earth (ground) from negative?

Thanks

PAULARGETYPE

In 1956 They Went To 12 Volt And Negatve Ground

MikeWA

Some of the 6 volt cars (talking about all makes now, not just Hudsons) were negative ground, some were positive- but when they went to 12 volts, I don't believe a single one remained positive ground. Same deal with tractors. Cars were pretty much all switched to 12 volts by '56, but some of the 6 volt gas powered tractors lingered until the late '50's. As they added diesel models, all went to 12 volts, as there was just no way you could get 6 volts to spin a diesel fast enough to start it. Some say that the fact that you could use smaller wire for 12 volt systems inspired the "bean counters" (who would kill for a $1 cost saving per unit) to force the change to 12 volts.

Jon B

I think the question was, "when did they go to positive ground?" Not, "when did they switch to negative ground 12-volt".



The year would have been in the 20's or early 30's, I assume....unless they were positive ground from the get-go.

[Deleted User]

I have also been curious about this same question since I bought my 20' Essex. It is negative ground.



Dave Bean

Geoff

The first positive ground systems were I believe 1934. I'm not exactly sure why they did this, but I believe it was something to do with corrosion of certain terminals due to chemical action, but I'm willing to be corrected on this. To change polarity necessitates switching the ammeter and coil terminals, and temproarily connecting the armature terminal of the generator to the battery. The Auto-Lite voltage regulators used up to 1955 all had dis-similar metals in the voltage coil points, which oscillate rapidly, and if run with the incorrect polarity, will burn the points out.

Geoff.

ESSX28-1

Thanks to all for the replies inc Hudsontech who said 1934 presumably from his copious info sheets.

Essexly

hudsontech

ESSX28-1 wrote:

Thanks to all for the replies inc Hudsontech who said 1934 presumably from his copious info sheets.

Essexly

Well, the electrical data I have from 1933 says negative ground; the ones from 1934 say positive.

Based on that, and the fact that any diagrams I have from '34 up all say positive, it's my edumacated guess that 1934 was the year.



Somewhere along the line I seem to remember seeing a paper on the why's and wherefores of negative and postive ground. From what I can remember for years the conventional engineering thinking was negative ground. For some reason, one morning, everybody woke up and decided it should be positive ground. Had, as I recall, something to do with current flow.



However, I think 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. The only problem would be units designed to work on one system or the other. That could cause some headaches.



But, then again, I could be wrong.



Hudsonly,

Alex Burr

HudsonTech

Memphis, TN

Roger Harmon

This is my first ('46) Hudson, but all the Model T Fords I've owned have been negative ground. They have ranged from 1922 through 1927. All the Model A Fords I've had (1928-1931) have been positive ground.



R/ Roger.

Unknown

If my memory serves me correctly some of the mid thirty chevrolets had postive ground for one model and neg for the other. Dont remember which had what.

mars55

As to why they switched to negative ground in the fifties, I found this on the web.



2.4. Why Are Vehicles Negatively Grounded?



The best 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."

Unknown

hudsontech wrote:

Well, the electrical data I have from 1933 says negative ground; the ones from 1934 say positive.

Based on that, and the fact that any diagrams I have from '34 up all say positive, it's my edumacated guess that 1934 was the year.



Somewhere along the line I seem to remember seeing a paper on the why's and wherefores of negative and postive ground. From what I can remember for years the conventional engineering thinking was negative ground. For some reason, one morning, everybody woke up and decided it should be positive ground. Had, as I recall, something to do with current flow.



However, I think 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. The only problem would be units designed to work on one system or the other. That could cause some headaches.



But, then again, I could be wrong.



Hudsonly,

Alex Burr

HudsonTech

Memphis, TN

HEY ALEX, first bit of humor I've seen on here for quite some time . Got my funny bone with the EDUMACATED guess. While in the army I had a young fella in my platoon that came in and out a private and just could'nt understand it because he said he was the most EDUMACATED man in the outfit