G
George Herold
Guest
On Tuesday, September 3, 2013 11:18:02 AM UTC-4, Phil Hobbs wrote:
OK that's also the answer I got from here,
http://www.yesterdaystractors.com/cgi-bin/viewit.cgi?bd=nboard&th=848277
To quote from one response,
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."
George H.
On 09/03/2013 10:25 AM, George Herold wrote:
On Monday, September 2, 2013 10:19:09 PM UTC-4, Phil Allison wrote:
snip
IIRC the switch to negative ground was to reduce galvanic corrosion.
OK that's also the answer I got from here,
http://www.yesterdaystractors.com/cgi-bin/viewit.cgi?bd=nboard&th=848277
To quote from one response,
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."
George H.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510
hobbs at electrooptical dot net
http://electrooptical.net