Glen-L.com

I once saw the above tug in Ft. Myers Florida but don't know it's home port?

Now for the rest of the easy question for all you thinkers?
Why do we not use positive grounds on our automotive systems today and you will probably never see it again?

Well several issues comes to mind. We know that some of the installations of positive ground came from across the big pond that drive on the wrong side of the U.S. The same folks that also drive on the wrong side of the road use 220 as a standard for their in home power. It must have something to do with living on the other side of the Prime Meridian. HEHE!

But with a positive ground, old metal bodies corroded more. But rest assured, you can save your pennies, I don't smoke any cigars.

Not really a British idea - The Model A was Positive earth (as the British would say), the Second Marcus Autocar (circa 1888) used a positive grounding magneto ignition, and the first point make/break ignition. (sorta, the points were operated by connecting rod attached to the piston itself)


Way back in the first decade of the 20th century, electricity began to be better understood, and the concept of negatively charged electrons actually moving through a wire from the highly-charged (negative) pole of a battery to the less-highly-charged positive pole was agreed upon, engineers began to think about a switch to positive ground. It was further believed in the early years of internal combustion, that the spark was hotter when it originated from the (then thought) more highly concentrated electron charge coming out of the battery negative, and traveling to the weaker positive.

Their thought was that if a car battery's negative pole is connected to the frame, and you happened to park it against/near a metal pole-fence-building, the electrons would force themselves into the earth and discharge the battery. But if the positive pole is connected to the frame of the car, that wouldn't happen.

Later, when we discovered more of the actual behavior of electrons, and that 'leakage' idea was dismissed, the industry went back to negative-ground. British, being British, were among the last to change, Still, GMC used + ground into the mid 50's (while chev was neg ground. ) Don't ask how I learned, it involved smoke, a200 amp starter/charger, and non-friendly language.

Positive ground was abandon more for the reasons found in points burning faster, and problems with radiators clogging from mineral/metal deposits.

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Some plan to stroll through Saint Peter's Gates, I plan to go through them at 150mph... backwards... in a screaming ball of flame, with a glimmer belt wrapped around my head, and a NOx button in my hand.

VW's ran + ground too.

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Bill

I told my wife we needed a three-car garage for my projects...she told me to ask her for permission next time before I buy a house.
http://www.unitybuild.net

I read this in an automotive manual about 25 years ago and it made sense so I believe it. Believe it or not it's all about spark plugs? Back in the 70s when people started to get concerned about the environment most people knew the car engine was a big poluter because they all ran rich which meant raw gas was going out the tailpipe. The cure for this was to run lean which means excessive oxygen in the mixture. The problem this causes is that lean mixtures are harder to ignite and in some instances will not ignite. If you were aware of things at that time you Know that there were all kinds of solutions to try and combat this problem. One of those solutions was to provide a hotter spark at the spark plug which of course means more voltage. Some smart engineer determined that if the spark had to travel from the connection on the top of the spark, through the plug and jump to ground then ti met an awful lot of resistance because that part of the plug is probably the hottest thing in an engine. Remember more heat in an electrical circuit means more resistance and more voltage drop to overcome this resistance and less voltage at plug tip. Testing showed that 17% of the voltage was dropped within the plug. As mentioned in a previous post electrical current moves from negative to positive. Now the above condition only occurs if you have a positive ground. If you have a negative ground the current travels from the outer shell of the plug to the center electrode, it still drops that 17% as it passes through plug but the spark has already occured with full voltage.

Regardless, Your DC plug center post should be positve. Regardless of if it is hooked to a red wire or the ground block.

Bill

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Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build