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I have been graciously gifted a Sunset 70 ton locomotive. I have the body about ready to paint but I need to re-poweror re-work the drive mechanism. The old rubber belts are dried out and do not work anymore. I am thinking of using the sprockets and chain that Weaver used to use. I can easily get them. I also plan to replace the Pittman motor with one that draws less amperage, maybe a Canon. 

I am open to your suggestions.

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I have a flock of the Weaver Alcos with the chain tower drives, original drives.     I really like them.    With a little adjustment, they run smoothly and quietly..     And they are very easy to fix if something breaks.    Early on, when I first got them, I had a lot broken axle gears.    However, for some  years now, I have had very few broken parts, axle gears or sprockets.     A friend who was in the molding business theorized that the breaking gears could have caused by running the mold too cold, and when the delrin ran around the mold when poured and met, it really didn't weld right.  

Malcolm,

I will still be cutting ties today.  Having said that.  If we don't go the full re-power job, you might consider just replacing the belts and cleaning out the old lubricant.  A word of caution, I use the MXL belts and Sunset uses the 40DP.  They look like a perfect match but, trust me on this one, they are not.  I mixed the two one time and it didn't go well.  If you decide to replace the belts Stock Drive Products (SDP-SI) is the way to go.   Let me know and I'll get you the part number.

Jay

Last edited by Jay C

It is interesting that the belts on this loco degraded.    I have a PRR 2-8-0 and a USRA (PRR) 0-6-0 from Sunset with the original belt drives.    I think they predated the 70 tonner by some years.      Both still run very well and very smooth with no slippage or anything.     I also have a newer 2-10-2 that has that belt drive and it runs fine.

Based on that, I would seriously consider just replacing the belts and using the rest of the drive train as is.    I guess if you really want to replace the motor, replace with one the same size.

these are Just my thoughts about the drive.

I hope this meets the paragraph request properly!

Jay C posted:

Malcolm,

I will still be cutting ties today.  Having said that.  If we don't go the full re-power job, you might consider just replacing the belts and cleaning out the old lubricant.  A word of caution, I use the MXL belts and Sunset uses the 40DP.  They look like a perfect match but, turst me on this one, they are not.  I mixed the two one time and it didn't go well.  If you decide to replace the belts Stock Drive Products (SDP-SI) is the way to go.   Let me know and I'll get you the part number.

Jay

Jay,

I would like the SDPSI part number. A closer inspection of mine looks like the belts are stretched and too loose to engage. I may change the cogs for the belt too while the Loco is disassembled.

thanks, Malcolm 

Jay,

Thank you for the reply...ordered the last two belts...unfortunately my 30 year old Sunset Model 70 Tonner is having other issues.

This engine has been in storage for at least 25 years...I had forgotten that I still had the engine...untouched, unused...I’ve just jumped back into O Scale after 7 years from th3 hobby...I’m guessing over that time the motor brackets have come loose, the motor will only run when power it attached to the motor leads, the rear truck runs but the front truck is sporadic (looks like a loose or cracked tower coupling) and the kicker...when power is put to the wheels...nothing moves 🤨

Does anyone know of someone who can fix these issues. I contacted Scott at Sunset Models...end of story...no parts are available, including belts, and no one there knows anything about this model...all have either died or retired that had any knowledge of this engine...seems everything they handle is 3 rail...

So that’s it in a nut shell...I’m willing* to put money for repair because this was my first O Scale engine when I converted from HO in 1985...the person who sold me the engine was a close friend that I had known since childhood...so there is sentimental value to me.

sorry for the length gentleman but I’d really like to get this model running again.

Conway57

Good news!  Thanks for letting us know.

If the parts are stock, then yeah, I'm semi familiar with them.  I'll look at the examples that are here for work and see what I can come up with.  Is there any way you could take a photo of the broken (probably split) part?  I only ask so I'm looking for the same part(s) you have.

Jay

Jay,

The shaft coupling is ok...I removed the female end of the shaft / slip coupling for clarity...the issue is with the .125 ball coupling that is attached to the tower bearing/shaft...

As stated earlier...the issue I have is slipping with the ball coupling on the tower shaft...i cannot fine any cracks...I just think that the I.D. is worn...I applied thick super glue  again and it seems to be holding, earlier I did the same but I believe that I applied too little and after running for ten minutes the ball coupling came loose.

Conway57

Okay, I think you have the same issue with yours that one of these has down here.  I seriously doubt glue will hold.  These appear to be Delrin and, unless you have the correct adhesive it won't hold.  The one I have that's split looks fine until you look under magnification.  It has a tiny split.  I could make a brass sleeve and press it onto the coupling.  I might even have a replacement piece.  No guarantees it won't split either.  Might, might not.

Jay

Jay,

our problem is solved...I think..I have the “Sunset Models Care and Feeding Instructions for GE 70 Tonner”

Sunset says that the “universal parts” are all Athearn...I found all the parts on EBay...

* 1/8” x 3/32 worm gear universal couplings (6) #40051 @ $3.66

* universal drive shaft...I purchased the last one...🤭

So I think this solves our parts problem...🤔🤔🤔

I’ll let you know once I install the new universal coupling...right now the super glue seems to be holding...

Conway57

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