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ronin

Need help: US steam locomotive overhaul

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ronin

I know this is primarily a Japanese trains site, but many people seem to have trains from all over and I am hoping someone can help me out. 

 

The topic at hand is regarding the one piece of n gauge equipment most responsible for kicking off my continued interest in the hobby, the 2-8-8-2 mallet, specifically for N&W.  My father had (I now have) one of the apparently original n gauge mallets by MRC with the plastic siderods.  It has never run since I can remember, but it was such an impressive looking train, I was just fascinated with how it would look rolling down the track. 

 

Fast forward a few decades and the 2-8-8-2 is now in my possession (still static sadly) but I have finally gotten up enough nerve to dig into it to see if I can get it going.  I also came across a local guy selling a small fleet of steam locomotives, including a few 2-8-8-2 's, although the slightly later ones sold by ConCor.  They are obviously the same basic package with a few changes to the details.  

 

I was hoping to get one or two of them rolling, but so far I have been thwarted.  So now I am going back and hoping someone can explain to me the basics of how the train is supposed to get power and ultimately turn the motor and thus the wheels.

 

Here are some pics of what I've got right now.  I took the wheels off and sanded the connection where the metal plate in the tender touches the spingy thing which touches the wheel axles and sanded the wheel axles as well.

 

So my assumption was that the wheels in the Tender provide power from the rails to the motor in the locomotive itself which turns the output shift of the motor, the first worm gear, the drive shift and the second worm gear.  Is this correct, or are the drive wheels providing power to the motor?  After sanding everything, the headlight does come on when power is turned on, but the drive wheels don't react.  They are not bound up.  I dropped the drive wheel assemblies to make sure they could turn pretty easily.  It seems like the motor is not getting power (or the motor is dead).  I checked out 3 different 2-8-8-2 chassis and they all reacted the same.  What am I doing wrong, or what is wrong in my logic?

 

Thanks,

 

Eric

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Edited by ronin

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ronin

Few more pics...

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ronin

I found this information:

 

"Pickup on all versions is the same - right-rail pickup is provided by six of the right side drivers and left-rail pickup is provided by four of the left side tender wheels (with the center wheels on each truck being electrically neutral). The pilot and trailing trucks on the locomotive are electrically neutral as well."

 

From this webpage:

http://www.spookshow.net/loco/riv2882.html

 

This tells me the drive wheels are part of the electrical path, but I still am not clear in my head how the full circuit path goes.

 

Any feedback is welcome.

 

Eric

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Kiha66

From what I remember trying to fix some of these before, the tender picks up one rail and the drivers pick up the other.  However the motors seem to usually be pretty bad, and I wasn't able to get the ones I worked on running.   Bachmann recently released the EM-1 in N scale, which may be a easier alternative to trying to find a replacement motor for this loco.  Another idea is to remove the motor entirely making the locomotive a dummy, and put a tomix or kato power chassis under a boxcar. 

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roadstar_na6

I‘d first try to apply power to the motor directly to see if it‘s the problem or if it just doesn‘t get power from the rail.

 Fitting another motor In it shouldn‘t be that much of a problem really, it just has to fit in the casting.

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ronin

Alright, I made some progress.  As you suggested, roadstar, I applied power directly to the motor.  At first, I still got nothing so I went ahead and pulled the motor completely out and then applied power to the motor with only the motor shaft, the first worm gear and the first part of the connector to the drive shaft.  Success!  The motor hummed right along, no hesitation. 

 

Next I disassembled the second worm gear assembly from the chassis, and that had some resistance to it so I disassembled further and got it turning pretty smoothly.  

 

I reassembled, touched the chassis to one rail and the wire to the other rail and I had TWO worm gears turning!

 

Reassembled to a rolling chassis and I finally had a 0-8-8-0 rolling under its own power.  Wasn't smooth so I assume the wheels will need to be disassembled and cleaned up, but there is finally hope.

 

I have some Lebelle lubrication products coming so I'll clean and lube it all up and see how she runs.

 

Thanks!

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Edited by ronin
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brill27mcb

Yes, the wheels will need to be cleaned well, and also the contact wipers and whatever they rub against.

 

Rich K.

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ronin

One thing I don't have my head wrapped around yet is the wheel assembly and the connection path from wheel through whatever to the chassis/motor.  Can anyone more clearly explain that or have some images or websites that explain it?  I call myself searching, but didn't find anything. 

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Tony Galiani

The most recent issue of N Scale Modellers Australia has some steam locomotive repair articles that look useful.  They focus on repairs to two American style steam locomotives and the issue can be viewed on line at http://www.nscale.org.au/nsm.

They seem pretty extensive and detailed.

Cheers,

Tony Galiani

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ronin

Thanks Tony!  That is really cool, and I have alot of reading ahead of me.  The information in issue 39 on DC steam locomotive basic electronics is awesome.  Really helps me understand how the system is supposed to work.

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Tony Galiani

Great.  I have been skimming previous issues on that web site and there are quite a few articles on N Scale steam.  Even though this is not something I plan to do, I have learned from reading them.

I plan to add an excursion train to my next layout but will go the easy route and purchase a Kato stearmer for it!

Cheers,

Tony Galiani

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Welshbloke

The wheels are only insulated on one side. So the axle is live to the uninsulated wheel and contacts the bogie block. The bogie block takes power from the axles up to the main chassis block, which in turn feeds the motor.

 

Hornby used similar from the 70s to the 90s. Diesel and electric locos would have insulated wheels on the left side on one bogie and the right side of the other. A single wire would connect the unpowered bogie to one motor terminal, the other being connected to the motor block to pick up via the uninsulated wheels on the motor bogie. Steam engines were much the same, just replace the wire with the tender coupling pin and loco drawbar (which used a brass pin and a pair of brass wiper pickups attached below the hole in the drawbar to rest against the sides of the pin)

 

Try dribbling a bit of washing up liquid into the gearing and gently rotating the wheels by hand, then carry on doing so under a warm tap. This will remove all sorts of dried grease and dirt from the drivetrain. Ultrasonic cleaners are even better but not something everyone has to hand!

Edited by Welshbloke
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ronin

That is a great reminder.  I happen to have an ultrasonic cleaner...

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ronin

Ok, I took apart one bogie.  If I understand correctly, the power goes from one side of the track through the metal wheel into the axle, which is insulated from the other wheel to prevent a short.  The current then continues from the axle to the bogie housing simply because the axle rests on the bogie housing, correct?  Next, the bogie housing rests up in the chassis and this friction touch is what allows the current to continue on to the chassis and then through the metal chassis on to the motor.

 

Does this all sound correct?

 

Thanks for the hand holding,

 

Eric

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Edited by ronin

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cteno4

Keep taking a lot of pictures as you pull stuff apart like this! Really helps later when reassembling.

 

jeff

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