Author Topic: Locomotive problems  (Read 963 times)

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Bob

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Locomotive problems
« on: January 14, 2020, 08:45:08 PM »
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Hi all -

I am having all sorts of issues with locomotives, and am not quite sure what to do.  First up is a Kato SD70ace.  I was cleaning the wheels by picking up front trucks while the rear wheels were on the track, then placing the rear truck on paper towel with rail cleaner why running the loco.  Did a great job cleaning the trucks.  but, when I reversed the process - no power.  I took the shell off, and noticed (could have done this without taking the shell off) a brass tab that contacts the middle and front wheels is bent downwards (upwards when looking at the trucks upside down).  This is indicated by the red arrow in the first two photos.  In contrast, the brass tab on the opposite wheels is in place and not sticking up (green arrow).  Do I need a new truck?  Is this even possible?

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My second question is whether there is a write up on TRW or someplace on the web about basic loco maintenance as well as a good manual, in real layman's terms, about DCC decoders.  I have several locos that seem to suffer from poor electrical pickup, including a new Scale Trains AC4400, and I have some that when on the programming track can be detected (MFG number, decoder number, various CV values, but when placed on the track just won't do a thing.   Any good sources of info I could look up?  Thanks!  Bob

wm3798

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Re: Locomotive problems
« Reply #1 on: January 14, 2020, 10:45:13 PM »
+1
While I don't have that particular locomotive in my roster, my experience is that often parts are not assembled with 100% accuracy at the factory, but with a little bit of work, these simple things can be corrected.
The first thing I do is try to separate the mechanical from the electrical... problems are usually based on one of those two issues.
Try disassembling the trucks and re-seat the contacts.  99% of the time, that's going to be the problem.  The shoes just aren't making contact the way they should, and re-seating them will usually do the trick.

As for mechanical problems, you can identify these things when the lights are on, the motor is buzzing (in other words, the electricity is getting to where it needs to go) so you probably have something out of alignment in the drive train, like a bearing block rotated 90 degrees, or you have something gumming up the works, like cat hair, scenery materials, a bit of ballast, or some other obstruction.  In rare instances, you may have a broken part.

If you can establish that the electrical path is a complete circuit, and the mechanism is free of any obstructions, then the last resort is that you have a bad motor, or more likely, the brushes are out of alignment, or worn out to where they no longer function.

The only real teacher in any of this is experience.  If you have an old beater that doesn't want to work, try tearing it down, cleaning it thoroughly, and putting it back together.  Get a can of spray contact cleaner, and some good model railroad gear lubes, and you'll be amazed at how easy these mechanisms are to understand.

As for DCC, there are programming tricks you can do to test the settings, but in the end, you again have to make sure the decoder is mechanically installed correctly, and electrically connected the way it needs to be.  I used to have an old motorized chassis connected to a terminal strip that allowed me to test the operation of a decoder before I installed it in a locomotive.  Primitive, but effective... at least for the hard wire decoders of old...

Try the take it apart and put it back together trick, and let us know what you find out.

Oh, and word to the wise, work on a surface that will keep the tiny bits where you can see them.  I usually have a piece of felt I put on my work bench.  If you end up launching a coupler spring or a tiny screw, it's good to know more or less where it lands...

Lee
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Lee Weldon www.wmrywesternlines.net

jagged ben

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Re: Locomotive problems
« Reply #2 on: January 14, 2020, 11:12:54 PM »
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That particular Kato truck design (also used on newer SD40-2) is particularly flimsy and finicky.  Yes, the contact is out of place and that's at least part of the source of your problem if not the entirety.  Not quite sure how to describe how to fix it using just words.  You can take those trucks apart and put them back together.  If you're not super inclined to do so then a new truck is an option if they have them available.

You might try searching Youtube for N scale loco maintenance.  It could be a wild goose chase but some people post some good stuff on there.

dem34

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Re: Locomotive problems
« Reply #3 on: January 15, 2020, 12:45:31 AM »
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That particular Kato truck design (also used on newer SD40-2) is particularly flimsy and finicky.  Yes, the contact is out of place and that's at least part of the source of your problem if not the entirety.  Not quite sure how to describe how to fix it using just words.  You can take those trucks apart and put them back together.  If you're not super inclined to do so then a new truck is an option if they have them available.

You might try searching Youtube for N scale loco maintenance.  It could be a wild goose chase but some people post some good stuff on there.

Just messed around with 2 Kato Locos last night and finicky bits of brass seems to be a good wright up of the issue I had with them.

Now to try to adress Bob, I have the exact same locomotive on a cradle right now. Looking at you're picture, the tab thats sticking up can kinda be described as a jumper. It partially sandwiches itself in the contact for the outer axles. Try poking it down with a small flathead screwdriver and see if that helps with it. Beyond that though unfortunately mine has the motor taken out at the moment so I can't step by step with it.
-Al

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Re: Locomotive problems
« Reply #4 on: January 15, 2020, 01:41:43 AM »
+4
Bob, for as much as I'm a fan-boy of Kato, with this mechanism design, they have jumped the proverbial shark.  It has soft suspension for the trucks, the middle axle in the tucks is also sprung (for better contact with the rail?), and they have very fine pitch gears.

All of this results in a model which runs like a Swiss watch, but it is very delicate and does not handle rough handling (even if that same type of handling was perfectly acceptable of other models).  Even routingw wheel cleaning can be considered as rough handling.  Plus even very small debris that get into those fine-pitch gears will make these models run very rough.

The thing you see stickign out is the soft suspension spring for the center axle bearing cup.  I have never seen it dislodged this severely.

Here is the only photo I can find of that area (this truck sat across electrical block and part of the truck melted).  I have taken the truck apart, but the metal sideframe/bearing cups are still embedded in the plastic sideframe.  But this gives you a good view of that center axle cup and the thin U-shaped soft suspension for it (it is all part of the metal sideframe/bearing cups).  The center drive axle needs to be riding inside the bearing cup.



As I see it, the only way you can fix this would be to take the truck apart ,and see if you can bend the metal sideframe/bearing back to its original shape.  If the replacement trucks are available, that would be much easier option.  And when you run and clean these locos, treat them very gently.

And I also recommend a very simple modification which will prevent debris from entering the truck and those very delicate gears. Take a strip of masking tape and place it over the gear openings on the bottom of the trucks, as shown here.  The tape will not interfere with the gears, and the openings for debris to enter the truck are now closed.



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Mark W

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Re: Locomotive problems
« Reply #5 on: January 15, 2020, 01:57:07 AM »
+3
...Do I need a new truck?  Is this even possible?...


... I have several locos that seem to suffer from poor electrical pickup, including a new Scale Trains AC4400, and I have some that when on the programming track can be detected (MFG number, decoder number, various CV values, but when placed on the track just won't do a thing.   Any good sources of info I could look up?  Thanks!  Bob


Hi Bob,

What you show is one of two things.  It could be just an incidental bend in the center axle pickup.  Carefully poke it back up into the truck and you'll be fine. 

Or, what I'd bet on, is you don't have the gear tower properly seated into the truck frame.  There is a little nub on the side of the gear tower that keeps the upper tab of the pickups centered in the contact strip.  When properly assembled, this nub should be beside the contact tab.  But as it happens, it tends to just come down over top.  You should be able to reach in with a needle or paperclip and pull the tab outward and slightly up, and allow the plastic nub to fall into place. 


https://i.imgur.com/ZVAQFO2.jpg


https://i.imgur.com/paLYf9v.jpg


https://i.imgur.com/gaOrivj.jpg


https://i.imgur.com/oGNKG3S.jpg




On the overall pickup issues, I'm curious how you have your track wired.  Do you use a bus?  How far apart are feeders?
Assuming all track is cleaned, working fine on the program track but spotty on the mainline could indicate voltage or signal drop. 
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peteski

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Re: Locomotive problems
« Reply #6 on: January 15, 2020, 02:30:21 AM »
+1
This photo Mark posted perfectly shows the debris (fuzzy fibers) stuck in the idler gear's teeth.  The masking tape modification will greatly reduce ingestion of this crap.  :)

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Bob

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Re: Locomotive problems
« Reply #7 on: January 15, 2020, 07:40:55 AM »
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Wow!  Thanks so much everyone - what a tremendous amount of knowledge and experience.  I will try to re-seat this thing this evening, but will also see if replacement trucks are available!  This is a great example of what makes TRW such a great site - people taking the time to share information and help others.  Sincerest thanks!

Mark W

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Re: Locomotive problems
« Reply #8 on: January 15, 2020, 11:45:10 AM »
+1
This photo Mark posted perfectly shows the debris (fuzzy fibers) stuck in the idler gear's teeth.  The masking tape modification will greatly reduce ingestion of this crap.  :)

Unfortunately, this is the result of a living with a puff ball of a cat.  But I will definitely be implementing the masking solution!  Brilliant idea!  8)

Otherwise, I don't think the Kato ACe is near as delicate as you describe.   And it certainly is not over-engineered in my opinion.  In fact, I would call it the pinnacle of mechanism design!  Every single part of the mechanism has a clear and simple role to make the engine run perfect, yet still allows very quick and easy maintenance. 
I'll give you the part about those fine tooth gears acting like hair and debris magnets though, yet even tangled as my truck shows, my units still run flawless! 

And when it does eventually need cleaning, I can have them disassembled, cleaned out, re-assembled and back in service in as little as 15 minutes.  Maybe 10 with the aid of the CGNscale Assembly Tray!  :D


https://i.imgur.com/OTKCgOZ.jpg
« Last Edit: January 15, 2020, 12:11:10 PM by Mark W »
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peteski

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Re: Locomotive problems
« Reply #9 on: January 15, 2020, 04:14:28 PM »
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Unfortunately, this is the result of a living with a puff ball of a cat.  But I will definitely be implementing the masking solution!  Brilliant idea!  8)

Otherwise, I don't think the Kato ACe is near as delicate as you describe.   And it certainly is not over-engineered in my opinion.  In fact, I would call it the pinnacle of mechanism design!  Every single part of the mechanism has a clear and simple role to make the engine run perfect, yet still allows very quick and easy maintenance. 
I'll give you the part about those fine tooth gears acting like hair and debris magnets though, yet even tangled as my truck shows, my units still run flawless! 

Oh I agree with you. I'm a self-proclaimed fanboy of Kato and I agree that this type of mechanism ia a pinnacle of design. Properly cared for, it will perform like a finest Swiss watch. But unfortunately these models need to be handled more delicately than models using older design.

I'm the loco maintenance guy for my local NTRAK club and for other friends, and from personal experience I can tell that some owners of those locos are harder on them than others (and I directly see the results of the rougher handling).  I See something similar with Kato GS-4 and FEF-3 locos. Both are extremely well designed, but also prone to mishaps due to not being handled delicately.
--- Peteski de Snarkski

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jagged ben

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Re: Locomotive problems
« Reply #10 on: January 15, 2020, 05:21:03 PM »
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It's just the sprung middle axle on the Ace truck that is over-engineered and delicate.  This is comparing relatively to Kato models that don't have that feature.

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Re: Locomotive problems
« Reply #11 on: January 16, 2020, 02:28:08 AM »
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I think you probably have all the info you need in the above posts, but I recall having this problem a few years back (along with having a unit whose truck would fall out if you looked at it crossly).  At the time I found a nice video about fixing these issue by none other than Mike Fifer (@fifer) and it's still up on YouTube:


Bob

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Re: Locomotive problems
« Reply #12 on: January 16, 2020, 01:11:10 PM »
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Thanks Gary!  I found Mike's video about cleaning trucks, but not this one that shows so well how to re-install.  This supplements all of the helpful comments above!

Bob

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Re: Locomotive problems
« Reply #13 on: January 16, 2020, 10:10:15 PM »
+1
So, one of the pickup tabs was covered by the plastic housing and so not making contact with the shoe, or whatever you call the long brass thing.  I put the tab in the correct place and now the loco runs like a champ.  Thanks for the help!