OK I will show my complete lack of knowledge here, My 1959 4104 is positive ground, I have been reading on how to change over to Neg ground and my first question is how do I know if I have an alternator or a generator by looking?? I googled what is the difference in alternator and generator and understand what the difference in function is but how do I know by eyeballing what I have?, Mine is gear driven, mounted on the rear of the 671 behind the compressor but looks different than the generator pictured in my 1958 4104 Maint. Manual.
Also if anyone has written instructions on changing from Positive Ground to Neg. please give me a shout..
Thanks in advance for any help!
If this needs to be posted under ask a dumb question forum maybe we can open a new forum as I will probably have more in the future..
Rick
I never saw a 50D postive ground alternator one way to check is turn the lights on at idle or watch your amp gauge a big drop in voltage at idle you will have a generator.
good luck
Mine was a '55 and if yours is a '59, I'm not completely sure. It makes sense that if it is positive ground, it is a generator. Look in the regulator compartment at the right rear of the bus. If it has the large black regulator, you most likely have a generator.
To change polarity (this is from memory) you:
1. rewire or replace the rectifier bank used for the alarm buzzer.
2. replace the oil pressure and temperature gauges
3. Re-cable the battery for negative ground.
4. "Flash the field" on the generator. That is, connect a wire from the battery lead to the field lead for just a second to change to polarity of the generator.
That should do it. Nothing else will be affected by the change. All the motors, lights and relays will still operate properly.
Anyone else jump in, it's been twenty years since I did it.
Alternators have a rectifier/brush assembly instead of a commutation (brush-only) assembly on the back side. In the bottom picture it's the lower half unit, since rectifiers are Diode (semiconductor-based) they usually have some form of heatsinking (you may see cooling fins).
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fwww.freepatentsonline.com%2F6970357-0-large.jpg&hash=1a91d1495c26185706ae44f590b3b70c47fa5c36)
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fimg.neons.org%2FAGN%2Faltntr1.jpg&hash=4b41fc15830f0ee3e45cacfb87fffdccdf0574b9)
-T
It does have what looks to be an oil line running to it with a oil drain plug on the bottom of the housing....do the generators have an oil line?
Rick, I think I sent you the PDF that came with my bus. It explains the conversion from gen to alt and pos to neg ground...Cable
Post a pic then we can tell you if it's an alt or gen.
Fe2-03 got your email thanks,
I just had a very enjoyable telephone discussion with John in Palestine TX, it looks like I have a 50DN Alternator in the 4104... The oil line and drain plug were 2 of the giveaways. At this point since the electrical system seems to be working great in the bus I am going to leave it as is. John is really up on the 4104's and answered a lot of questions for me not just about the alternator but on several things I was unsure about. After talking with John I like my 4104 even better!
I want to thank everyone for the help and emails, I have been around several forums and groups in the past but I think the folks here are the best as far as helping out goes..
Thanks
Rick
I'm not sure what it would take to change the alternator to negative ground, but it would be worth looking into.
As it is, with positive ground, you will be wasting a huge potential of that big alternator as you will not be able to interconnect it with your house batteries.
I for one would sure like to see his wiring diagram on the 50D to make it work on a positive ground.
good luck