Re: Cutout relay on generator
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Posted by ks on September 07, 1998 at 18:48:50:
In Reply to: Cutout relay on generator posted by Jerry Ruble on September 06, 1998 at 20:50:17:
:Okay, let's get a couple of things straight before we begin. First, the modern solid state cutout replacements will work at any voltage-they are not 6 or 12 volt specific. They do, however, require that you observe the polarity. If the tractor is still positive ground(and the battery isn't charged up"backwards-which isn't as uncommon as you would think!) then observe the labeling on the cutout that pertains to positive ground (or vice versa if negative ground).
Secind, any dc generator is "self-exciting"(most "alternators"are not)and do not require excition voltage from a light bulb to get things going. So, forget that line of thinking in this case.
Now, to the problem at hand. The generating system used on your Allis did not have a voltage regulator as some tractors(even available on Allises)did. It instead used a cutout(as you mentioned) in conjunction with a "output control". The output control is an integral part of the headlight switch. If memory serves me, all the way in was low charge/headlights off, first notch out was high charge headlights off, second notch was high charge headlights on....etc. The field terminal was in no way connected to the cutout, a wire from the field terminal went back to the h/l switch. in the innermost positionn the field terminal was connected to ground through a resistor mounted on the h/l switch. In the other positions, the field terminal was connected directly to ground for full generator output.
The way this system was intended to work was this: If you started the tractor and were going to run it all day, you left the switch "in", if you were only going to run it a short time and shut it off, you pulled the switch out one notch for a higher charge rate to build the battery up faster-one major drawback to this system was that if you ran it long at that rate, the battery would be overcharged and boil. Usually with the lights on, the battery recieved about the same amount of current as in the low position of the switch.
You stated that you weren't getting 6 volts at the field terminal, you wouldn't.
If your headlight switch is unuseable, you can compensate. The easiest way to get around a bad switch is to "full field" the generator. This will cause the generator to produce full output though, which will overcharge the battery n a short period of time, but the generator that your tractor is/was equipped with has an adjustable third brush that we can use to lower the generator output to an acceptable level. Her's waht you need to do: First make a short wire to connect the field terminal to ground-this "full fields" it. Start the tractor and observe the ammeter-it will probably be cranking out 20 amps or better. You want a target amperage of about 8 amps, any more will cause overcharge problems.If you are over 8 amps, stop the tractor an dremove the band from the generator. You should be able to do this with the generator still on the tractor. Loosen the small round headed slotted screw on the commutator end plate of the generator.(this is a single #10 screw-not the three#6 screws holding the little reservoir plate on) then looking in through the band hole, determine which brush holder is the "movable" one. A little wiggling should tell you which one will slide around. You will need to move it away from the adjacent brush to lower the output. move it some, tighten the outside screw, start the tractor and see how it's doing. Still too much? move it a little more(with the engine off!) Not enough? move it back a little bit. Remember, a target amperage of about 8 amps. If for some reason you were going to run the tractor all day long on a hot day, you could disconnect the field wire for a while to keep from boiling the battery. For occassional use, 8 amps is about right. If you have any questions(I think I surely covered it all) feel free to email me. If you don't find three brushes in the genrator, someone has substituted a car generator and you will never be able to use it with just a cutout-you'll have to invest in a compatable voltage regulator. ks
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