Gear tower trouble in my AC6?

[robert3985]

1st. - In Ron's image above I see that the tower appears to be cracked all along it's length. Yes ? ?
         Also in looking at the image I see what appears to be a crack and some DIY soldering on an
         item. Don't have a clue what it is biut it appears to wrap around the drive shat next to a
         u-joint. Good or bad ? ? Could be my eyes.

The soldered "item" you're looking at is a brass bushing holder that solders to a couple of tabs on the frame to keep the drive shaft aligned with the gear tower.  I got a bargain on a brass Key Big Boy that "wouldn't run" and the problem was that the Big Boy's similar bushing holder had come unsoldered.  It was an easy fix using Superior Supersafe No. 30 Soldering Flux (no new solder) and my 250W American Beauty Resistance Soldering Station and the tweezer tool. 

If I had had to use an iron to fix it, it would not have been nearly such an easy fix because the tweezer tool both holds and heats the parts, keeps them all in position until the solder freezes.  Took me about five minutes to fix after half an hour of disassembly.

Looks like this bushing holder in the photo has been re-soldered.  A bit of engine black paint would improve its looks exponentially.

If you're getting into brass engines, it's a great idea to bite the bullet and get yourself an American Beauty Resistance Soldering Station.  I'd say it's almost essential for many repairs that require re-soldering.

Cheerio!
Bob Gilmore

[ATSF_Ron]

Thanks for that info, Bob.  I was guessing it was either a brass or copper bushing for alignment purposes.  It seems like a solid soldering job, albeit ugly, lol!  I took some more closeups.  Here's what I observed.

1) The two halves do NOT appear to be touching on the left side of the "slit."  At least at the top.  The right side IS touching.  Does anyone think the left side is a problem?  I really don't know.

2)  I VERY gently poked around that gear tower piece with tweezers and an Exacto #11 to check for movement.  I also took the tweezers and squeezed gently to see if the "slit" space on the left side could be closed up.  It didn't want to move.  At least with the gentle force I was using.  Is that something that can be fixed with soldering or a drop of something like epoxy?  Should I even worry about it?  Other than the open space on the left it seems fine to me.

3)  I can see the worm gear through the top of the slit and through the space on the side in one of the photos.  There does not appear to be any flashing or crumbling of the gears or gear tower material.  When I had the bottom covers off for initial lube a couple weeks ago, everything looked brand new.

So there we have it.  What do y'all think?

[peteski]

OK, I have a comment and a question.

1st. - In Ron's image above I see that the tower appears to be cracked all along it's length. Yes ? ?
         Also in looking at the image I see what appears to be a crack and some DIY soldering on an
         item. Don't have a clue what it is biut it appears to wrap around the drive shat next to a
         u-joint. Good or bad ? ? Could be my eyes.

It is not a crack. The gear case (tower) is made of 2 pieces (like the photo I posted earlier).  The seam is visible.  On Ron's example there is also some metal chipped at the top edge of each half, but since that chipped area is blackened, I suspect it was like that from the factory.  it is just a cosmetic defect.  The thing that worries me a bit is that the gap between the halves seems to be wider that what I woudl expect. But if the worm bearings don't have much play then all is well.

The chipping might be due to the way these are made.  Injection-molded white-metal castings have an area where the metal is injected (similar to plastic injection-molded parts which have gates that connect them to the parts tree).  The chipped are is probably where the gate was. The gate was then broken off the gear case halves, causing the area to look chipped.

[peteski]

Ron, if there are no obvious flaws in the gear case (like Zinc-pest), the worm bearings are not loose, and the worm spins freely, then I think all is well.

[ATSF_Ron]

Thanks Peteski, your explanation makes sense to me.  I also think the gap is a bit large, but as I stated earlier there is no movement I could detect or make happen with gentle pressure.  I don't believe that any N scale forces generated by this loco's drive could cause any separation of the two halves.

[Mike Madonna]

To "piggyback" on what Peteski said, if the worm is held in it's proper orientation/position relative to the ring gear, the mechanism should turn smoothly forward and reverse without a hitch (so to speak)....

[ATSF_Ron]

Thanks Mike. Yes, everything seems to be in order. No binding that I can detect. Time to put this puppy back together.

[ATSF_Ron]

Well ain't this a b&*#h!!  As I was putting things back together, this little tank like structure fell out from under the front of the cab.  (Tweezers are pointing where it goes) Apparently a bad solder joint.  And wouldn't you know it?  It's also got a hole in it where the screw goes to hold the entire front end of the shell together with the frame.  FUN!!  Calling it a night.  This is a job for tomorrow.

[ATSF_Ron]

So it appears there’s a second hole behind the tank on the shell. I’ll most likely need to screw the thing on before repairing the bad solder joint. Otherwise things won’t line up when I go to install the screws for final assembly.  I’m guessing super glue or epoxy won’t cut it for this job? Hoping to simplify the fix 🤷🏻

[peteski]

So it appears there’s a second hole behind the tank on the shell. I’ll most likely need to screw the thing on before repairing the bad solder joint. Otherwise things won’t line up when I go to install the screws for final assembly.  I’m guessing super glue or epoxy won’t cut it for this job? Hoping to simplify the fix 🤷🏻

Is soldering it is not a viable option then my recommendation would be to clean the joining areas very thoroughly and use the slow-setting J-B Weld epoxy. You'll have to find a way to immobilize the tank until the epoxy sets.

If you want to attempt soldering using conventional iron, I would recommend low melting point solder like TIX.  But this will be difficult since the parts are painted, and paint does not conduct  heat very well. Unless you want to partially strip the paint  . . .

[ATSF_Ron]

Stripping the paint can work. Most of the body of the tank is hidden. I’ve never stripped a brass loco. Paint thinner on a Q tip?

[ATSF_Ron]

Well s#$t!  This just gets better and better.  In attempting to reassemble, I lost one of the microscopic washers.  Down into the mechanism!  I finally figured out a way to get the front driver set out.  Under the front driver set there's a nice LARGE space between the shell weight and the shell.  Naturally, that's where the flippin' washer decided to go.  And it ain't comin' out!  The weight is soldered to the shell, quite sturdily.  No amount of shaking or gentle tapping is getting it loose.  Yes, I looked over the drivetrain with the highest powered optivisor set I have and it's definitely not in the drive train anywhere.  Ah well.  Everything should run fine without them.  It did before when I forgot to put them back.  They go under the screws of the small bar that connects to two driver sets together.

While the shell was off I decided to see the mechanism run while open.  I have a concern.  I think it should be a relatively easy fix though. The sloppy solder joint on the brass bushing mentioned by Carl and Bob in previous posts seems to be broken.  As the loco ran in place (I held it in place and let the drivers spin), I watched the mechanism closely.  That solder joint moved ever so slightly up and down, free of its mounting post.  I think there's enough spare solder there where if I heat it up it should flow back down to the mounting post.

I think I'm very close to having this loco's relatively minor issues fixed.  And it really is a smooth runner for a mid 80s brass import.  Time to go get a pencil tip soldering iron.  That's a long overdue purchase.

[ATSF_Ron]

Ooops! Forgot the pics...

Also, in one of the pics you can compare the tooling marks on the front gear tower compared to the rear one with the "slit."  It's much cleaner.  In watching the mechanism run, I noticed zero issues with the rear tower that has the "slit."  Looks good to me.

[Mike Madonna]

Hmm, well this is interesting. I see that loco has a Sagami motor. My AC-5 has a Mashima. I say "interesting" because they are from the same 1986 run. Also, I noticed a "Southern Pacific Lines" tender in one of the pics. What loco is that from?

[ATSF_Ron]

Mike, that is interesting.  Apparently they didn't stick with one type of motor.  The SP Lines tender is a whaleback tender from a 2-8-0 I recently picked up.  Trying to find the best fit of various Micro Trains couplers I have.

Got my new soldering iron, so I'll be attempting to repair the bad soldering job soon.