MTH 44 tonner stalling issues

It is most likely poor ground.  If you are running Ross switches with non-derailing, try hitting/holding the switch button for the direction you are going even though the switch is thrown.  This will ground the isolated rail.  I bet the engine goes through.

I have figured out what I need to upgrade the supercap in the 44-Ton locomotive, just haven't had the time to do the deed.  Given the smaller board, I'm somewhat concerned about damaging the charging circuitry, so I'll have to design my solution to minimize the inrush current for initial charge of the larger capacitor while still allowing full current to flow out of the capacitor when needed.

gunrunnerjohn posted:

I have figured out what I need to upgrade the supercap in the 44-Ton locomotive, just haven't had the time to do the deed.  Given the smaller board, I'm somewhat concerned about damaging the charging circuitry, so I'll have to design my solution to minimize the inrush current for initial charge of the larger capacitor while still allowing full current to flow out of the capacitor when needed.

Hey John, just to clarify - you're talking about upgrading the standard ps3 supercap configuration (provides keep alive for sounds, etc. but not motors), correct?

If you have figured out where to tie in to the main voltage bus on a ps3 board, so that you could provide motor keep alive as well, please share - I have a supercap design just waiting. 

David- Both outside rails are fully grounded. My switches are manually thrown. The only thing left I could ground would be the points themselves since they don't seem to make very good continuity just from my ground throws pushing them against the outside rails. All that said it seems quite possible that the problem is loss of ground even still as the stalls seem to frequently happen just at the moment one of the grounded wheels rolls onto a plastic frog or other component of the switches. I wish RCS would use metal frogs...everything else about them is so top notch. (I've actually been to their shop and seen how they build things--very impressive!)

GRJ- I take it you think the supercap is the best fix, but also far and away the most daunting and risky for me to DIY... Any thoughts on adding pickups? that would seem like it may accomplish the same thing and be less invasive?

I haven't researched powering the motors as I think it would be somewhat involved.  If I were to undertake such a project, I'd probably pick something larger than the 44-Ton model to make the fitting easier.

KevinF posted:

David- Both outside rails are fully grounded. My switches are manually thrown. The only thing left I could ground would be the points themselves since they don't seem to make very good continuity just from my ground throws pushing them against the outside rails. All that said it seems quite possible that the problem is loss of ground even still as the stalls seem to frequently happen just at the moment one of the grounded wheels rolls onto a plastic frog or other component of the switches. I wish RCS would use metal frogs...everything else about them is so top notch. (I've actually been to their shop and seen how they build things--very impressive!)

GRJ- I take it you think the supercap is the best fix, but also far and away the most daunting and risky for me to DIY... Any thoughts on adding pickups? that would seem like it may accomplish the same thing and be less invasive?

Kevin,

Try another test.  In the dropout area, Place a jumper from a known good ground to the frame or a CLEAN (take the black off) wheel.

The caps are for sound.  No big deal there.  Some have complained about the short shutdown.  Not an issue for me.  This has nothing to do with your shutdown problem.

David Minarik posted:

Try another test.  In the dropout area, Place a jumper from a known good ground to the frame or a CLEAN (take the black off) wheel.

The caps are for sound.  No big deal there.  Some have complained about the short shutdown.  Not an issue for me.  This has nothing to do with your shutdown problem.

 

How do I take the black off the wheels?

I was wondering if I could jump a grounded axle to a known good ground as the wheels do seem to have less than perfect continuity when tested upside-down...

Often times after it stalls, simply wiggling it around in place will cause it to come back to life, but it won't move. I am under the impression that the small supercap causes drop outs from momentary power losses and this kills the sound and command electronics and when it picks power up again it is in conventional mode in neutral which is why I need to fully shut it down and restart before it will move again.

Pardon me if this question is naive.  Does this issue occur on Realtrax or Fastrack switches?

Thank you.

KevinF posted:

David Minarik posted:

Try another test.  In the dropout area, Place a jumper from a known good ground to the frame or a CLEAN (take the black off) wheel.

The caps are for sound.  No big deal there.  Some have complained about the short shutdown.  Not an issue for me.  This has nothing to do with your shutdown problem.

 

How do I take the black off the wheels?

I was wondering if I could jump a grounded axle to a known good ground as the wheels do seem to have less than perfect continuity when tested upside-down...

Often times after it stalls, simply wiggling it around in place will cause it to come back to life, but it won't move. I am under the impression that the small supercap causes drop outs from momentary power losses and this kills the sound and command electronics and when it picks power up again it is in conventional mode in neutral which is why I need to fully shut it down and restart before it will move again.

Kevin,

I use a wire wheel to get the black off.

That is definitely a ground issue.  Taking the black off of the wheels might help some but the real problem is insufficient ground because of the traction tires.  The real fix is two metal traction tires.  One on each truck.

You might call MTH to see what they recommend.

IC fan posted:

Pardon me if this question is naive.  Does this issue occur on Realtrax or Fastrack switches?

Thank you.

I am not super knowledgeable myself, but IMHO any track plan with switches has  the potential (however small it may be) of having a critical combination of deadspots that could cause a stall for some engine with just the right pickup roller and grounded wheel combo. Back-to-back switches may be a good thing to avoid if you ultimately just want reliable performance. That said you are probably unlikely to experience this problem using a plug-n-play track product in a typical o-gauge style layout.

On the other hand I am building a switching layout with double slips, #4s, etc. all very close together. Ultimately I am just asking for issues...and hoping I can find a solution that doesn't involve giving up on the engine for something less fickle or the whole darn project...

David Minarik posted:

That is definitely a ground issue.  Taking the black off of the wheels might help some but the real problem is insufficient ground because of the traction tires.  The real fix is two metal traction tires.  One on each truck.

Any chance you'd share in detail how you did that? I really like the looks of that.

I question if it's the pickups that are the issue.  I wonder about the conductivity of the wheels to the frame, you have four traction tires, so only the remaining four wheels for track connection. When I measure conductivity between the wheels on the two trucks, I get varying readings, I'm thinking that they're more likely the issue than the center rail pickups.

In any case, there's no reasonable possibility to add pickups that I can see, where would you put them?  I'm wondering if axle wipers would help...

I've posted this before, but if you are not sure whether it is a power or ground issue, here is a way to determine that conclusively.

My very first thought was center roller, but when investigating the actual stall spots ground does seem more likely as the wheels are often on the points, frog and only one on solid grounded rail. Also wiggling in place restoring power seems to support this idea.

Further when I tested continuity I was surprised that I didn't get a sharp ring from my multimeter between the various combinations of axle to wheel to other truck axle, etc.

Keep the ideas coming please, but right now my plan for tonight is to try a hot and ground jumper to see if one or the other makes a difference and then go after cleaning the wheels and axle bearings.

Thanks guys.

Thor-I didn't see your post until after I posted mine.

I actually tried exactly that, and generally had continuity, but even by touching the probe to a wheel I may move it enough to get continuity back.

I have a scale lighted caboose with a similar truck/pickup roller spacing that goes through with only a slight flickering (lights never go out). Hence it seems to be an extremely momentary loss of either hot or ground (the flickering), which is exacerbated by the undersized supercap and causes the electronics to shut down...

That said my degree is in civil engineering, not electronics...

I think some axle wipers to frame ground would be of assistance.  I think the conductivity of the axles to the frame is somewhat suspect.

gunrunnerjohn posted:

I think some axle wipers to frame ground would be of assistance.  I think the conductivity of the axles to the frame is somewhat suspect.

I agree. This also sounds like a promising idea. Any advise on how to execute that? Would simply screwing the wiper in with an existing screw in the truck frame be sufficient or would I have to pull the shell and hardwire it? Where could I find a donor wiper?

It just has to be connected to the truck frame, one of the sideframe screws would be a good choice.  The outside rail power goes to the power truck frame, so anywhere on the frame.  I use some brass stock for wipers, and I also have the MTH wipers for freight and tender trucks that I could use.

Kevin,

You can lift the wheel set out of the truck.  Sand/turn off the lip that holds on one of the traction tires.  Press on the metal tire.  Done.

I have not checked to see if there is tubing out there that is the right size to make a traction tire.  I just cut mine out of aluminum on a lathe, which I understand many people do not have access to. 

John,

On what wheel would you install a wiper?  The fronts are not making enough contact with the track and the rears have traction tires.

Well, I see the axle to frame issues with the wheels without traction tires, so clearly those would get the wipers.

I agree that removing one traction tire on each truck (from opposite sides if it were me), would be a good solution, but as you say, not for someone that doesn't have the tools.

The easy way to do this is probably to get a matching wheel and just swap it for the traction tire wheel.

To all of our surprise my problem seems to be center rail pickup.

I sanded the black off the idler wheels and attached hot and neutral jumpers.

The neutral jumper had not effect (although cleaning the wheels may have helped) and I was still stalling, but the hot jumper resulted in perfect performance!!! Crawled through my double slip at 1smph repeatedly!!

I'm going to remove the neutral jumper and attach the hot jumper to a roller on a caboose and do some more testing, but I'm definitely happy to have a preliminary diagnosis.

I have one idea of how to add rollers. I'll try to post a sketch in the morning.

Anyone have ideas?

What is the "hot" jumper connected to for these tests?

gunrunnerjohn posted:

Well, I see the axle to frame issues with the wheels without traction tires, so clearly those would get the wipers.

I agree that removing one traction tire on each truck (from opposite sides if it were me), would be a good solution, but as you say, not for someone that doesn't have the tools.

The easy way to do this is probably to get a matching wheel and just swap it for the traction tire wheel.

John,

I had not thought of pressing on a "non traction tire" wheel.  That is a great idea!

Kevin,

Glad you got it fixed!

Where do I get a matching wheel ? I looked when this first came out. Can I somehow get a non-powered wheel from MTH ?    You MTH tech's have better access than myself. I realize I have to bore out the axle hole.

Clem

I'd try to get one of the non-powered axle sets, you can just pull the wheels off those.  In addition, the wheels "look" pretty standard sized, so there may be any number of matching wheels around.  I doubt MTH went out of their way to use non-standard sized wheels.

John.... thats what I was thinking, however the powered axle and the dead axle are different axle size, so you would have to bore out the wheel hole. I should be able to do that.

Update    

I got mine fixed !!    I found a copper wheel or axle wiper, then cut and bent it to shape. it fits on the truck side frame mounting screw and rubs on the wheel. I can now go 3 mph and even stop on my large Ross turnouts.  I thought it was the turnouts at first, so I put jumper wires on the moving rails to the dead rails, that helped but not for the 44 tonner. The wiper seemed to fix it,    I'm doing more tests now. 

Clem

The jumper wires go from rail to rail only

Hot jumper was 22ga solid wire wrapped around the screw that holds the pickup roller. The other end I held to center rail with my finger.

Can't say I fixed it, only that I'm reasonably confident that I know what to fix.

Not that anything is broken. I am well aware that I am pushing the limits of what you can do with 3rail using such a small loco.

After seeing Clem's post, I think I'm going to add similar wipers while I'm working on it, just to be ahead of the next issue. I'll update when I make more progress.

I've made up a few wipers myself recently, where I had less than ideal grounding. I used 0.010" phosphor bronze sheet. It's easy to cut, form, and solder. Here are a few pics, details are in this thread.

These wheels are smaller than standard diesel wheels.  You might just try swapping them with the front axle.

Dave the 44 tonner axles are different diameters.     

Look for something with the smaller wheels, pilot trucks for some steamers come to mind.

well after more running of my 44 Tonner, I found that I had to put wipers on both trucks. like my photo in above post. Tried it even on switches that where not modified and ran thru without missing a beat  even stopping and starting. The worse switches are the larger Ross#6  #8 and the real pain 120-096 curved turn out and mine are even worse because I super elevated them. I do not recommend doing that.  I included a short video of running slow thru the switch that caused the most problem, 120-096 super elevated to flat transition

Clem,

That seems to work nicely!

Dave ...... seems to be still working   and the fix was fast, easy and cheap, just remove one screw and it returns back to the way it was.  

Clem, are all your switches wired like this:

I had to do this even on my RCS #4, to get my 44 tonner to even somewhat consistently run through...

And yes, I have continuity between my pickup rollers. I'm honestly puzzled. Here's a spot it stalled last night on my RCS double slip:

Both rollers look like they have contact with powered rail sections. One wheel is solidly on outside rail, but here's the thing--as as soon as I touched my hot jumper to center rail it started back up and holding the jumper, moved back and forth over this same area repeatedly at 1smph...but visually, it doesn't look like a pickup problem.

Am I missing something? I guess based on Clem's experience, I need to try wipers before anything more drastic.

Most of my Ross turnouts are not wired .  I wired some to improve ground only (not like diagram). The video was my worst offender, once I put the ground wheel wipers on  all is right in my world.  Make sure that center diamond is wired.  My switches get power from each track coming into turnout. Make sure all your outside rails are connected to common ground and all center rails and diamond are connected to common hot +. I do not use my turnouts for division between blocks or power districts.

Clem  

After my measurements, I figured the wheels could be a likely suspect.  Since there's a cure for those, and no easy cure for the rollers, at least you can solve half the problem.

I just have to finish my little circuit to add extra capacitance to the supercap bank for a complete job.

Clem - can you make me a set of wipers for my engine? I just returned from York with a new one … they were blowing them out for 225. And yep, made it half way around the layout and it does not like Ross Reg switches.