Dead spots

[siemer]

I've got a new and annoying problem with an almost-new Forney that's begun to sputter and/or stop consistently at two places along the right-of-way -- both of them when it reaches a crossover junction with the optional turn in its direction.  The track and wheels are clean and the engine operates perfectly everywhere else.  Also, my other loco (2-8-0) has no such problems passing over the crossover junction.  I'm running the basic EZ command station with DCC and sound in both locos so there should be plenty of power.  The engine behaves as if it hits a dead spot -- sometimes stopping altogether and sometimes sliding past the problem and starting up again.  Any ideas?

[railtwister]

Have you determined if the dead spot is caused by a short or open circuit condition? If not, you can use a light bulb wired to the rails to determine this, if the bulb goes out even momentarily, it's probably a short, but if the light stays steadily lit even when the loco stops, it's an open circuit problem. Once this is determined, you'll have a better idea of what you're looking for.

Regards, Bill

[siemer]

Bill:  That's a good start and I appreciate it.  But wouldn't a short or open circuit affect all passing locos similarly?  This seems to affect only the Forney, maybe because it has a much shorter wheelbase than the 2-6-0 or the 2-8-0?

Mike:  Now that's an interesting thought, especially since it appears that the frog is where the break hits.  Still curious why it happens on two of my crossover turnouts and not on the other four.  In any case, it might explain why it affects only the Forney, i.e., maybe the wheel and truck configuration causes the double contact you describe.

Anyone else, please jump in.  When it comes to electricity, I'm the village idiot.

[railtwister]

Bill:  That's a good start and I appreciate it.  But wouldn't a short or open circuit affect all passing locos similarly?  This seems to affect only the Forney, maybe because it has a much shorter wheelbase than the 2-6-0 or the 2-8-0?

Mike:  Now that's an interesting thought, especially since it appears that the frog is where the break hits.  Still curious why it happens on two of my crossover turnouts and not on the other four.  In any case, it might explain why it affects only the Forney, i.e., maybe the wheel and truck configuration causes the double contact you describe.

Anyone else, please jump in.  When it comes to electricity, I'm the village idiot.

The short could be caused by something specific to a certain locomotive, due to it's length, wheel arrangement, pickup system etc. Since your problem only seems to occur with your Forney, it's likely locomotive specific. Also, you want to look carefully at the clearances around the lead & trailing trucks for a momentary short. DCC decoders are sensitive to any loss of power, even one so quick that you might not notice it with analog DCC. Because of the high current power that is constantly on the rails, most DCC systems have extremely sensitive circuit breakers that will trip quickly when other breakers wouldn't. They may also reset themselves quickly after the short has cleared, making it hard to determine what happened. If you have other DCC locos on the track running off the same booster when the problem occurs, it's more likely that the problem is caused by the Forney losing contact momentarily. The Forney also has less wheels on the track providing contact. One of the big culprits in problems like this can be point fed turnout frogs, which tend to be unreliable, sometimes losing their contact with the main rail when the weight of the loco passes over them. Locos with a longer electrical footprint might not notice it while shorter ones will stop every time. An 0-4-0 Porter or Davenport side-rod diesel can have serious contact issues at turnouts because they have such a small footprint, so they can make good test units. The Davenport diesel is actually a fine little loco.

Regards,
Bill

[az2rail]

Are you using switches with powered frogs? If not, you will have problems with small wheel based engines.

Bruce

[siemer]

Nice dialogue.  I'm learning a lot and trying all the suggested solutions one at a time.  These are powered turnouts, by the way. 

In the meantime, since this is starting to appear like a design problem, meaning a small footprint loco is going to have frog problems crossing a crossover turnout, one question remains:  why would Bachmann engineer a loco that is somehow incompatible with one of its track items?  Shouldn't the packaging for both include a warning -- "Beware, our $360 Forney locomotive will usually sputter and die while passing over our $60 crossover turnout"?  Just a thought.

[siemer]

The trailing truck is the power pickup.

[railtwister]

Our module club uses Peco On30 turnouts because they are very reliable, better than most on the market, but we have found that they still benefit from power feeding the frog though an extra set of contacts connected to the switch machine, rather than simply relying on the points making contact with the stock rails to feed the frog. With this setup there is still a chance of a wheel back touching the open point as the wheel passes. So far, that hasn't been a problem, though. I'm not familiar with the way the Bachmann DCC controlled turnouts are wired, since they are part of the EZ-track system, and I haven't got an EZ-track layout. I do know that there are very few truly DCC friendly turnouts on the market, and almost all turnouts require a certain amount of tweaking to be reliable. I don't think there's any good justification for this, it's just they way things are. Maybe if they all worked perfectly, it wouldn't be a hobby!

Also, even with trailing truck pickup, the Forney would only have a maximum of eight wheels picking up (lead trucks seldom ever provide any pickup), and the overall length from the first driver to the rearmost trailing wheelset is relatively short compared to a loco with a tender. I don't recall if the Forney has true 8 wheel pickup (although I think it does), or if the drivers pick up from one rail and the trailing truck picks up from the other rail.

Regards,
Bill

[siemer]

Just to close the loop.  I've tried just about everything.  In fact, this morning I sacrificed a chicken to St. Giselius, the patron saint of turnouts.  But nothing has worked.  So I'm stuck with the fact that three other locos, including a little guy (2-truck shay), are having no problems.  So I am concluding the short is in the Forney and sending if off for testing to my pals at Bachmann.

Thanks for all the thoughts and suggestions.  Much appreciated.  If you were in the neighborhood, I'd buy you all a beer.

[railtwister]

Just to close the loop.  I've tried just about everything.  In fact, this morning I sacrificed a chicken to St. Giselius, the patron saint of turnouts.  But nothing has worked.  So I'm stuck with the fact that three other locos, including a little guy (2-truck shay), are having no problems.  So I am concluding the short is in the Forney and sending if off for testing to my pals at Bachmann.

Thanks for all the thoughts and suggestions.  Much appreciated.  If you were in the neighborhood, I'd buy you all a beer.

Bachmann may not be able to duplicate your problem, since I doubt they have a test track with the same turnouts installed, probably just a straight test track. Have you determined that the problem is indeed a short circuit rather than an open one? Since both locos have sound and DCC, if you have both on the track at the same time with the sound and lights on, but with the 2-8-0's throttle in idle while the Forney runs through the problem area, and BOTH don't go dark & quiet when the Forney's problem occurs, the problem is likely an open circuit. When I visited my local hobbyshop yesterday, I thought of your problem and took a closer look at the Bachmann EZ-DCC turnouts just to satisfy my curiosity. It looks like they have an insulated frog, but where the two rails converge to meet the frog, they are fairly close together, so it's possible a wheel that is slightly wide, and has a few extra thousandths of an inch extra sideplay, could bridge the gap causing a momentary short. You mention the problem occurs on only two out of six crossovers, so I'm beginning to think it's more likely a problem caused by either the turnouts having a slight mass production tolerance issue, or perhaps an all but invisible anomoly in the installation on your layout (perhaps an ever so slight twist, dip or hump?). Mailing the loco back to Bachmann without knowing for sure that it is the source of the problem (and whether that problem is a short or an open circuit) will only cost money for shipping and waste your time waiting for the turn around. No one is born with any knowledge of electricity, it must be learned, and troubleshooting the problem is one of the steps in the learning process. One trick you can try is to try running the Forney without it's lead truck, which could be causing a short, or if there's any imperfection in the track, could be causing the loco to shift it's balance enough to lose contact at just the wrong time. Another trick to spotting a short, especially with DCC, is to run the loco through the problem area in near darkness and look for any sparks when the problem occurs.

Hang in there, you can figure this out!

Regards,
Bill

[Linzthom]

Do you have, or are to get,  a Porter 0-4-0. If you have a problem with that then you know it is the turnout

Lindsay T

[Jim Banner]

Good contact between the wheels and the rails is only one of the requirements for good electrical pickup.  There is another set of contacts to worry about, the ones that pick the power off the wheels.  I am not sure which type the Forney uses - axle bearings, phosphor bronze wheel wipers, or??  But check that they are properly adjusted and clean too.

Whether or not this will help or is a waste of time depends on the result of the short or open test suggested earlier in this thread.  Divide and conquer is the order of the day when it comes to diagnostics.  The simple light bulb test can help you decide whether you have a short problem or an open problem.  If you don't know, you can spend days looking for a short when the problem is an open, or vise versa.

Jim   

[grandpops]

If you've determined that is not a short, then try this: When the engine stalls, gently push down on all the corners of the engine to see if you can detect a pickup point that is losing contact with the rail. I have a similar problem on one #6 turnout and found that one of the driver wheels on my 2-6-0 and 2-8-0 is lifting off the rail. When I push down on the engine I can feel the corner go down slightly and the engine then starts up.

Try it, who knows, it might work.

Walt

[rayport]

May I also suggest that you reverse the engine and try running it through the turnout that way. The rear truck is a powerful pickup on the Forney and is also very flexible. Running at slow speed and close observation should lead to clarifying many of the points raised in earlier posts. My bet would two miniscule deviations in tolerance coming together briefly - these can be very difficult to spot. The suggestion to insulate possible contact spots near the frog and closure rails is a good, quick and reliable solution to many intractable problems. Good luck! The Forney is a great engine, for my money the 0-4-0 Porter had short wheelbase pickup problems that are not found on the 0-4-2 Porter; if you have the oportunity try running this pair of engines through this point setup, the trailing wheels on the 0-4-2 are sprung in such a way as to almost guarantee continuous contact.

[NarrowMinded]

I had a problem with a little ballast that would contact the flange and lift the wheel just enough to stop it.