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Good morning forumites. I have a GP9 from the recent run. It runs the entire layout including  4 turnouts with no problem. On the section below, the unit loses power and stops at three of the four crossover sections as it's traveling straight on either side of the double mainline. The unit travels through the nearest turnout on the right just fine but stops on the others. When the locomotive stops it also causes a short as the nearby crossing gates start to go up and lose power. This is the most sophisticated configuration of turnouts on the layout. All others are not connected to additional turnouts and are simply spurs. I have pictured the unit upside down so that you can see how the pickup rollers are configured. Each roller has a spring under it and are not at an angle as they are on Lionel and MTH units. I'm not sure if this could be related to the problem. As most, who are familiar with the 3-rail Sunset product know, these units come with TMCC installed. My Lionel(Legacy or TMCC), MTH, etc. locomotives do not have this problem. In addition to trying to run the unit forwards, backwards, and upside down, I also tried connecting a caboose to it. Still nothing. I'm trying not to go into panic mode but all of my practical solutions have not been working. Watch the short video as the unit stops right as the trucks under the cab reach the other side of the grade crossing on the turnout. Any suggestions, insight, or thoughts are welcome.

Dave

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Last edited by luvindemtrains
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I’m with Bob, and along his thoughts, the outside of the grade crossing might be built up too high too, allowing a wheel to ride up over on the “dirt” and off the rail, …and if that’s where your detection is for your crossing gates, that would make sense…..if your power is good through the rails, then clearly it’s beaching itself off one or more of the rails….

Pat

Gentlemen,

The height of strips on the grade crossing aren't interfering in this case. That was my original thought. Furthermore, when  I run the locomotive from the other direction it encounters the same issue. In the latter case, it hasn't even made it to the grade crossing. Also as stated, when I run the unit over the grade crossing on the right side it doesn't stop on the first turn out. This only happens on the other three in both directions.

Dave

Last edited by luvindemtrains

I think you need to look for continuity between the wheels, not the rollers.  That it dies on the crossing (which I assume are tripped by isolated rail) and switches are involved makes me think that you're not getting pickup of the outside rails from both sides of the locomotive. Either the wipers need more tension or there's a wire somewhere that may not have a good connection. If you have the rail isolated for the crossing and a dead switch rail, it may not be touching common and that would also shut it down.

You said you are dealing with a short circuit when the engine stops. The troubleshooting steps offered so far (feeder location, wood strips in the grade crossing, wiper tension, bad connection) assume you have an OPEN circuit when you lose power.

If you have a short, that means that something is connecting the hot rail to the outside rail, thus causing the short. This sounds more like a wheel gauge issue to me. The wheel(s) may be touching the guard rail(s) on the switch and shorting out the power.

Last edited by Rich Melvin

Boliermaker1-If that is the case, what would make this problem unique to my Sunset/3rd rail units and not Lionel or MTH?

Rich-In that same vane, why would this only be happening in this area and not the other turnouts on the layout? The turnouts are all the same.

I will check this out when I got back in there. Will report back...

Dave

@Rich Melvin posted:

You said you are dealing with a short circuit when the engine stops. The troubleshooting steps offered so far (feeder location, wood strips in the grade crossing, wiper tension, bad connection) assume you have an OPEN circuit when you lose power.

Rich, a great big DUH here!  I totally glossed over that point, and it makes much more sense!

Rich-In that same vane, why would this only be happening in this area and not the other turnouts on the layout? The turnouts are all the same.

If that's the case, then the issue may be with the turnouts themselves. They are not all manufactured 100% identical. The manufacturing tolerances are not that tight.

If you have a turnout that's off by a little bit one way, and the wheel gauge is off a little bit the other way, that could be your problem. You need to carefully check the rail positions on each of the turnouts, and check the gauge of the wheels on that loco. My bet is that one of the guard rails on a switch is slightly out of position, and the wheel gauge is a bit tight on at least one of the wheel sets.

I would look at all the gaps between the center rail and the outside rails, at the locations indicated by the arrows:

I can see a wheel or pickup roller bridging either gap.   (The roller is more likely, due to the lateral profile of the Sunset roller.)  Try putting a thin piece of tape over the ends of all the center rails where they are close to the outside rails. See if that solves the problem

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Last edited by John Sethian

I think Boilermaker may be on the right track.

My assumptions is the crossing gate is controlled using insulated rail.  The fact that the engine dies once it leaves the curved track and is solidly on the next track and once it dies, the crossing gates go back up because they are no longer triggered by the wheels bridging the outside rails.

Just for fun, use a jumper to connect the two outer rails on the section where the engine dies and see if the engine again powered up.

My guess is that since 3rd Rail makes their locomotive for both two and three rail, the axels may not be solid from one side to the other like they are on Lionel and MTH.

Good luck in your search,

Don

@DGJONES posted:

I think Boilermaker may be on the right track.

My assumptions is the crossing gate is controlled using insulated rail.  The fact that the engine dies once it leaves the curved track and is solidly on the next track and once it dies, the crossing gates go back up because they are no longer triggered by the wheels bridging the outside rails.

Just for fun, use a jumper to connect the two outer rails on the section where the engine dies and see if the engine again powered up.

My guess is that since 3rd Rail makes their locomotive for both two and three rail, the axels may not be solid from one side to the other like they are on Lionel and MTH.

Good luck in your search,

Don

The axles most certainly aren't solid from the looks of things, they have wheel wipers on all the wheels.

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@luvindemtrains its not a 3rd rail thing at all. Its usually just an assembly error. The MTH 3-2 trucks are also prone to the same issue. If the pins arent set right in the truck, only a single side picks up and the other side is electrically isolated.

If you look at the picture of the truck, you can see the plastic insulators in the right hand side wheels.  The dual pickup wipers should tie the sides together in the wiring, but its gotta be wired right, with enough tension on the wipers to keep them in contact with the wheels as things jostle around. The traction tires render most of those wheels electrically useless, so its really only 4 wheel pickup, unless the flanges are also making some contact, which can be hit or miss.

I have a raft of 2 rail locos, including sunset, the axles are solid all the way through unlike some HO stuff.    On 2 rail units the insulation on one side is at the hub of the wheel.   there is a nylon bushing on the inside of the wheel, between it and the axle. 

Note there are traction tires on this loco in the photo, so there is only pickup on 2 wheels in the truck in the picture.    If the other truck is the same, that could be a pickup issue depending on conditions.

However, if there is a short, it points to something else, such as a wheel or roller bridging a gap across some rails on the switch.

Gentlemen,

You again show why the forum is a great place. Based on all of the information provided, I took off the traction tires. The locomotive runs through all the turnouts without stopping. I have run it light with no rolling stock yet, so I know the pulling power may not be at full potential. Is there anything else that I need to be concerned about with the traction tires being removed?

Dave

Last edited by luvindemtrains

Gentlemen,

You again show why the forum is a great place. Based on all of the information provided, I took off the traction tires. The locomotive runs through all the turnouts without stopping. I have run it light with no rolling stock yet, so I know the pulling power may not be at full potential. Is there anything else that I need to be concerned about with the traction tires being removed?

Dave

If there are no grooves in the wheels, then just run it with no tires. So long as it weighs enough it’ll still pull a fair amount.
If the wheels are grooved, you may or may not have 8 wheel contact, but maybe Scott has ungrooved wheels on hand if you’re up for swapping axles.

Dave, while going to a non traction tire wheelset will solve your problem. This engine may not be the only one you will ever see with an issue down the road. If the isolated rails only function is to trigger the crossing gates. Have you considered using sensors to trigger the signals. Azatrax has a great website with many scenarios in how to hook up their products. They even show an MTH setup. They work very well, come with detailed instructions and the best part is on ballasted track they are hardly noticeable.

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OK, check this video out. I did as Don suggested and the locomotive no longer stops.

Dave

I suggest you closely inspect the wipers, they may not be making contact with the wheels all the time.  The wheels have some side-to-side play, see if the wipers are in contact for the full travel.  You can form them to have more tension, that might solve a bigger global issue with this locomotive.

How so?

Dave

The experiences I have had with switch crossovers and ladders when specific locomotives stall is generally caused by an unfortunate span of either center rollers or in your case, the ground pickup on the locomotive wheels. I.e. there is a specific position where all wheels that make electrical contact happen to be on non-grounded rails. since the tires reduce the number of pickup wheels as your test by removing tires proved, maybe moving one of the tired axles to a different position will eliminate the non-contact scenario.

Since 3rd rail diesels have the same gearbox on all axles, it should be possible to move the wheelsets around. I would check the contact wipers first as John suggested.

I always make sure my switches have good and continuous outside rail grounding. I know Atlas has improved their jumpers but I always try to feed power on all sides of them. I don't run any trigger rails through the turnouts so I don't interrupt the outside rail continuity. Kinda stinks because some of my signals won't trigger right past the head, there is a delay until my train moves past the turnout(s). I just want to maintain consistent power. Everyone always wants to suspect the pickup rollers but seems to look over the fact that many engines have very poor grounding.

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