Wednesday, January 4, 2012

My Spinning Genny

No, I did not get fat, lazy and give up on this project.  I just got fat.  The holidays did sideline me, though, from continuing with the big, loud and dirty projects.  I had to resort to smaller "workbench" jobs where I could quickly escape to the garage for a few minutes of peaceful solitude.  Then, when the family wised up and realized I was gone much too long for just "taking the garbage out," I could come back in to be social without needing a shower.

This is a sideline project that I started back in August and FINALLY finished it.  It seriously should not have lasted this long.  I got hung up on a pair of impossible screws.  More on that later.  Here's how it all went down:

I bought a REALLY, REALLY bad "jeep" two years ago for $150.00.  It was a hodge-podge of M38, CJ2A, and GPW parts...and it was basically disassembled and rotted away.  When I cleaned out the tub, beneath decades of pine straw and leaves, I found a WWII generator.  Nice.  I can use that!  I will most likely use it on the next jeep, since it is 6 volts and the current jeep will most likely be 12 volts.

I couldn't find a picture of the generator before I disassembled it.  I thought I had taken one, but I guess I didn't.  Sometimes I get really excited to jump into a project and I forget to take pictures along the way.  Maybe if I hit it big time, I will hire a photographer to follow me around.  Or not. 

The outside casing (which is steel and about .5 to .75 inches thick) resembled the moon's landscape with pot marks from rust all over the bottom.  My best guess is because it sat for so long in the pine straw being subjected to the weather. 

I managed to loosen the smaller screws and get the end caps and pulley disassembled with only a few bad words spoken.
This is the armature pulled from the casing.

This is the backside of the end cap that is holding the armature.  The pulley slides onto this part of the shaft.

Yes, this a a VERY BLURRY close-up of the armature...what you can't see is the really cool Autolite and 9/42 (September/1942) date stamp!  I saw it and it was cool!

Backside of the pulley cleaned and freshly primed.

This is the inside of the front end cap that holds the two brushes that rest against a spinning armature.

With the bulk of the generator disassembled, I could now easily look inside of the casing.  The major work was yet to come!  There are two field coils screwed into the side of the casing that the armature spins between.  In a good generator, these field coils (which are copper wires wrapped about a hundred or so times in a specific shape) are tightly wrapped with an insulating cloth tape.  Approximately half of the cloth tape had disintegrated on these coils.  Not good...and that is a technical term.
Just good ol' fashioned nastiness. 
This is a good look at the two field coils and the shattered remains of the cloth tape wrappings. 

Same old nastiness, just a view from the opposite end.  You can see all of the exposed copper wires on the bottom.
Not good.

I did a bunch of research and was a bit intimidated about the next step.  Evidently, people try not to have to remove the field coils.  If they become unwound, evidently you become S.O.L.  However, I was intrigued and if I wanted this generator to function, I really didn't have a choice, so I pressed onward.  There are two massive screws that hold the plates that hold the coils to the inside of the casing.  And these two screws are almost impossible to remove.  They are installed very tightly and then combine 65+ years of being in place and they just won't move...kind of like a stubborn donkey.  If the screws are damaged, replacement screws are few and far between.  From what I can tell, modern replacement screws are not available.  This is a one shot Charlie escapade.

Well, it was these two screws that sidelined me for a few months!  I soaked them in penetrating oil for days on end.  I broke several tools trying what I thought were clever methods to remove them.  I even tried wedging  the casing and a screwdriver socket wrench in a 10 ton press.  This and all kinds of other ridiculous methods got me absolutely NOWHERE!  I succumbed to defeat.  I boxed up the generator and went to a professional repairman.   He called me the following day and said it would cost approximately $450 to repair it and he couldn't guarantee it to work.  I asked if he could loosen the two screws and then send me back on my way.  I think he felt sorry for me because it was a "no charge" five minute job...that would most likely prove to be a futile waste of my time.

When I picked up the generator, I asked him how he loosened the screws.  He went old school...he beat on the sides of the casing with a BIG hammer and then beat on the screws themselves with a smaller hammer.  He did this several times.  Then he used a hammer with a punch to loosen the screws.  Huh.  Who knew?

When I removed the field coils, I had to be very careful and make sure I could remember EXACTLY which way was up when I reinstalled.  No turning back now.  I picked up some friction tape from Lowes and off to the races I went.
I removed the field coils and half of the tape was already gone.  Before removing the rest, I taped three of the already exposed sides.  Then, as I removed the old cloth tape, I would place a piece of tape on the remaining sides for support.  Yes, it was done this way originally, too.

The right field coil it done.  At the top, in the middle, you can see the one little wire that keeps the two coils connected.  I somehow managed not to break this wire.  Fun fact:  I did this delicate procedure at the kitchen table while Sarah's grandmother ate her lunch.  Sorry for the disgusting company, Nette!

I wrapped both coils and became VERY ALARMED.  It went way too smoothly.  I had to have done something wrong.  But I couldn't figure out what it was.

Once the coils were wrapped and looking really good, I went outside to finish cleaning the casing...inside and out...and give it a good looking paint job.

Now, everything was done and ready for assembly.   Hopefully, I could recall how it all went back together.  I was praying that my notes still made sense to me.

The other scary part of the reassembly was fitting the newly wrapped field coils back inside the casing.  I had read that it was very difficult and also very imperative to get them screwed TIGHTLY in order to give the armature room enough to spin and not rub the coils.  Again, I did it and it was relatively easy to do...which made me very nervous and suspicious of some wrong doings.  The armature was spinning like a top!

Assembled and ready for the bench test.
Again, I got too involved to stop and take any pictures.  Where the heck is that photographer?

With it all together, it was time to bench test it!  I hooked it up to my battery charger and...lights, camera, action...and nothing happened.  Shittake mushrooms.  I researched, again, the proper method to attach all of the battery charger's wires.  Still no action.  If I had done everything right, the pulley should "motor" or start spinning.

So then I opened the generator back up and began inspecting my handy work.  I was poking and prodding everything with my multimeter checking for continuity where it was needed and correct grounds elsewhere.  It seemed correct.  I then broke out the army technical manuals...TM 10-1015...and ran 4 out of the 5 assorted tests to check for any problems.  Everything checked out in order.  The one test I was unable to run was to check for a short within the armature itself.  For this, I needed a "growler" which I didn't have and it was too expensive to buy for this old generator.

So I reassembled it for the umpteenth time and stared at it for awhile.  I reattached the wires from the battery charger in a different configuration.  The positive lead to the armature terminal, the negative lead to a ground point on the rear end cap and a jumper wire between the armature terminal and field terminal...and then the darn pulley began to spin with a really good speed!  Granted, I don't have the equipment to test it's output, but damn, I got it to motor!  Case closed.  This thing is working in my book...and I didn't spend the $450 to fix it!  Just my own cheap labor, paint I already owned, $10.00 for two bearings and $1.50 in friction tape to wrap the coils.  I'm not counting any of the tools I broke trying to remove the field coil screws!
Bench test:  its motoring!  The pulley is spinning.  I wish my camera wasn't so nice, otherwise you'd have seen a blurred looking pulley.  In the end, I had assembled it correctly, but was incorrectly attaching the battery charger wires to test it.  Here, I finally figured out the correct set-up. 
Tune in later to check out what I am doing with my rear end...of the jeep frame!

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