 TAD: The generator on my VAC is an Autolite. I don't have the number handy as I am on the road. If you don't get the number by this weekend, I"ll stop back and post it. In the mean time, "Alberta Mike" was kind enough to send me a nice write-up on the wiring that got me through my job. I'll re-post it here and hope it helps you as well. ===== ===== ===== ===== ===== ===== ===== ===== I assume you know how and why the 3-position switch works but here's a simple explanation before any wiring details. In the full-in (#1) position, this is called "generator controlled charge" position (where the generator field circuit is wired to the wound resistor on the switch and then to ground). In the second or middle position, there is "no regulation" (or full charge) where the generator field is wired directly to ground (through the switch and switch body/dashboard mount). In the third or full-out position, the generator charge is again "no regulation" (full charge) exactly as in #2 position, however the switch is feeding juice to the tractor lights (via the switch) and then to ground (through the lights). You'd normally use the in-position if you had a strong battery that was charging well and not low. The second position would be when you wanted to put more charge through your battery (from the generator). And of course if you wanted lights, then the 3rd position would automatically ensure that you were getting full generator charge when your lights were on. Maybe it's also worth noting that you can adjust the charge rate of your third brush generator (has just a single-coil relay mounted on it) right at the generator itself by rotating the position of the third brush inside the generator). I could email you some stuff on doing that if you wish later. Now, as for the little wound resistor that is wired along the side of the switch, they are usually broken or messed up in some way. I have made them up myself by getting some nichrome wire (got mine from a school's science lab) and cutting off enough so as to have about 3 ohms of resistance through the length of wire. You'd have to do some fiddling with an ohmeter to find the length needed, it would vary with the diameter of the wire you get. Then winding this wire length around an insulated core of some type (maybe ceramic or fibre, anything heat resistant), looping each end with needlenose pliers, then wiring it into place. I have also purchased a 3 ohm ceramic resistor from an electronics shop (Radio Shack might have them). These have the winding inside a ceramic block, about 1 1/2 inches long and about 1/4" square in cross section. A wire protrudes from both ends and you just wire it into where the old resistor went. Now for the wiring into and out of the switch. First, there are a number of terminals (that you have labelledin your photo) that in some cases are continuous with other terminals via brass bar connections like #1 and #2 (or #3 and #6). I guess this just gives you more options to wire things onto the switch. Some of the terminals are not even used in a tractor like yours but could be I guess. I assume that your whole tractor is wired up properly (6V positive ground, big plunger-type starter button on the dash, ignition switch, etc.) other than the fact that you just don't know which wires come into and leave the switch, is that right? If you want I could walk you through the whole wiring setup in another email which isn't hard to follow. You should have two wires leaving the generator. One leaves the field terminal on the side of the generator (this sits alone and should probably be stamped F on the generator case). The other one leaves the terminal on the small relay box (note that there is a wire between the inside of the generator which goes into the relay box from underneath). At least, this is the set up on the generator of most 3rd brush generators. Now, where do these two generator wires go to? The wire from the generator field terminal goes to the terminal on your dash switch that hooks up to the resistor which I already mentioned. In the switches #1 position, generator field current goes from the generator to the resistor, through the resistor, then to ground (via the switch body). This controls the charge rate. This resistor terminal on the switch is not shown on your photo since it is on the other side correct? On the switch itself, the two screws which mount the resistor are about 1 1/4" apart. One of these resistor mounting screws is on a metal tab (to which a wire is attatched) while the other is on the switch case itself. Now, the second generator wire leaves the generator relay box (side tab connection) and goes to the negative terminal of your ammeter gauge on the dash. Then another wire leaves that same negative terminal of the ammeter and heads off to the switch to be connected to the terminal on the fuse holder (which holds and supports the little glass/wire fuse). This is actually a fuse for the light circuit. You'll notice that so far, NONE of the little terminals that you have numbered in your photo have wires attatched EXCEPT #4 which I think you have labelled as the terminal screw on the fuse holder mentioned above. Is that right, am I reading your diagram correctly? That fuse holder terminal (#4 I think) has the wire coming from the negative ammeter. All that's left now is to locate the terminal which would supply power from the switch to the light(s) of the tractor. Strangely enough it is the terminal that is NOT labelled on your photo because it is hidden behind the fuse holder metal on your photo. It would be below your number 3 terminal (or opposite to your # 5 terminal). That is the terminal which is hot when the switch is in the full out position (full charge, lights on). No other terminal back there is hot in the full-out 3rd switch position. So that's it (I think). If you want, I could walk you through the full wiring diagram, not a problem to do that, just let me know. If you're not 100% sure then that might be an idea. I could also tell you what all those other terminals on the switch are for, or at least in which switch positions they are "hot" but it's not needed on a simple tractor setup (maybe for some automotive wiring from the 20's or 30's when those generators were used on cars and trucks). ===== ===== ===== ===== ===== ===== ===== ===== Hope this was helpful. Frank-in-Tallahassee
’56 70D // ’90 855 // ’50 VAC // ’48 Cub
frank@fboerger.com
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