Hobart welder - generator lead insulation

Hi, all, just discovered the board. A lot of good advice here.

I'm working on an 1940s Hobart welder with a Willys Jeep engine. This machine has an exciter generator that also powers a 110 volt DC convenience outlet on the control panel. Feeds through a variable resistor to the the field windings on the main generator. Then the main generator has a bunch of shunt windings in series with the brushes, and a tap selector switch to choose how many of the shunt windings are in the circuit. There is also a current-sensing tap that operates a solenoid that idles the engine under no load.

Main question I have is about the generator leads, which are insulated with rubber-impregnated fabric. The condition of these is less than ideal and I'd like to reinsulate them, but don't know what kind of material to use or where to get it. The larger leads are flat, tinned copper, about 3/4" or so by about 16 gauge thick.

There's a polarity switch on it that's shot. DPDT center off, and rated for 15a 120v DC. It switches the field on the main generator. I tried patching up the switch but no go, there's a spring I can't replace. I can't find a DC-rated DPDT 120V 15a switch anywhere and wonder if anyone has sources.

Also the little 6v generator on the engine has a bad armature. Bearing went out, shaft wore down, and the laminations wore against the field plates and the magnet wire burned. I have a couple ideas for sources on that but would accept any suggestions.

Finally any info on the tap settings would help. They are numbered 1-5 but the 5 has lighter gauge wire than the 4, which is heaviest. I suppose I can experiment.

Thanks

Steve

try www.surpluscenter.com item no. 11-2122 its a 2 pole 4position rotary switch

Why not use heat shrink tubing to reinsulate the wires. You can find it at Lowes hardware, home Depot or any electrical supplier.

If the insulation is intact, but looks rough, you can brush on a number of products, not limited to the can of liquid plastic that you dip plier handles into to insulate them (I forget the name of the stuff, but most hardware stores carry it.) Saves on tearing things apart. Otherwise there are many slip on insulation tube makes/types available.

However if these are on the rotary parts, or hard to reach stationary parts, you can get "Formvar" from some electrical houses, otherwise big paint houses should be able to supply you with an acceptable equivalent to simply brush on the wires and be done with it.

As for the little 6 volt generator, chances are good that there was an automotive application that is almost identical. I might even have a few pieces if not an entire generator.

On the switch, There are many vendors out there with new stock, Mauser, Digi-key, etc. It is a standard bat handled switch used all over in industry by the description, so industrial supply companies like Graingers should even have it.

As for the shunt windings, depending on how they are switched into the circuit, I suspect they are switched parallel, so as you go down in number, your current goes up.

John,

Thanks for the insightful reply. I hadn't thought of using brush-on products and will see about finding some. That would be ideal, since as you say, there would otherwise be a good deal of disassembly and fiddling to sleeve the leads.

Regarding the switch, I've checked Grainger and Digi-key, also GC electronics, no luck. The problem seems to be the 120 VDC rating. Most DC-rated switches are rated for 12 or 36 volts, and those few that do carry a 120 VDC rating either won't carry the current or are in the wrong configuration. I have found a DPST switch that is properly rated, which is on back order, and I plan to use that in series with an AC-only DPDT switch which should work OK as long as it isn't switched with the other one on. It will take some panel changes but at least it will work. The original was a phenolic-handled DPDT center off, shaped like an ordinary light switch except with a longer throw on the toggle, with a mechanism to prevent switching from one polarity to another without releasing the handle in the "off" position first.

I did find a take-off generator to replace the little one for charging the battery and running the ignition, on eBay, where I also found a rebuilt armature for sale in case the take-off isn't rebuildable.

As for the shunt windings, I'm quite sure they're series connected. I disassembled and cleaned the tap selector, which is SP5T and has about 2 pounds of copper in it. It is a shorting, rotary switch, and when properly set connects to just one of the taps. Not a progressive-type switch that you would expect for paralleled windings.