Beacon question

K

Kenn Evans II

I have a 49 Kaiser Traveler which type of beacon would have been used on my roof top. There are three holes parallel with the windshield the center one 3/8 in. in diameter. the car is 6v positive earth. thanks for your help.
 
The motor in the beacon doesn't care about positive grounding, it will just rotate in the opposite direction of one that is hooked up to a negative ground.
 
Positive Ground Systems

Paul Steinberg said:
The motor in the beacon doesn't care about positive grounding, it will just rotate in the opposite direction of one that is hooked up to a negative ground.
Click to expand...

To any of the PCS "Electrical Gurus".... what was the advantage (if any) of postive ground systems? We had a number of Freightliner Trucks in the mid 70's that had this system that was totally differnt than anyting else on the road. While like Paul said, rotating lights would just rotate the other way, but other appurtenances like two-way radios, alternating flashers, electronic sirens, etc., needed convertors that were a constant maintenance problem. MM
 
to me it was just one more of the same fight we see in the industry today. the early years were about half and half, pos or neg ground. neg ground won out. the current would flow either direction and resistance would read the same. some though you got more power to the started out of pos ground. they solved that problem with increasing the voltage. just one more 8 track versus cassette things we get trapped into. now if they would just go back to sealed beam headlights they would make a step in the pos direction I think.
 
The switch from 6 volts to 12 volts came about because 12 volts was a more efficient method of powering the items in the cars. Take for example, the starter, you will note that the 6 volt wire is a heavier gauge than the 12 volt wire carrying similar amperage. As cars developed more accessories, there was a need for smaller wire diameters for the wire harness, hence the 12 volt change. The change to all cars being negative ground was an industry wide change to standardize cars. I have heard that a positive ground car eliminated corrosion issues, but have never seen any documentation to prove this. I do know that the automobile manufactures have been in talks for the last few years trying to come up with a standard that will move car electronics to the next level with a much higher voltage, which will result in smaller diameter wire bundles. Last I heard, they were still debating the question of 36 or 48 volt systems. I believe that it is the battery that is presently causing the problem with the change over. A 36 volt battery will require 18 cells, and that is going to take up a lot of real estate under the hood, and a 24 cell (48 volt) battery even more. Understanding the relationship of volts to amps, etc. is a complex equation. As an example, a 14 gauge solid copper wire is not as efficient in transferring current as a 14 gauge finely stranded copper wire. The longer the "run", the heavier gauge wire is required to carry the same amount of current to the end destination.
 
Rotation

A permanent magnet motor will reverse direction when polarity is reversed while an electromagnet motor will not. In other words, the motors in the Federal beacons as a general rule, will not reverse no matter which way the current flows.
John Dorgan


Paul Steinberg said:
The motor in the beacon doesn't care about positive grounding, it will just rotate in the opposite direction of one that is hooked up to a negative ground.
Click to expand...
 
You must log in or register to reply here.
Back
Top