Track Power Issue When Running 726RR on Fasttra

Run it slowly over the spot and note where the pickup rollers are. It sounds like each one  is on a non powered part of the switches.

John,  it will not run over the swtiches with the transformer set to less than 15 volts.  It just stops. as soon as the engine hits it.  It will not move forward or reverse, when I press the direction buttons on the transformer.   It will go over them with voltage set at 16 volts or greater.   It will run around the rest of the track at any voltage.  

I agree with @JohnH that your engine roller spacing is matching gaps in the switches, causing a momentary loss of power. At a higher voltage, the engine is travelling a bit faster, reducing the time the rollers are in the gaps - thus the e-unit is not triggered, and the engine goes on.

With the engine on the track, do the best you can to use a ruler to measure from one roller contact spot to the track to the other roller's contact spot to the track. Engine on track to measure because rollers spacing will change slightly when being pressed upward by the track contact.

Then you can slide the ruler along the center rail thru the back to back switches and see if the rollers would line up with the gaps.

Thanks for the feedback.  I will definitely do that.   If that turns out to be true, any suggestions for what I can do?   I am not having the same problem with my modern engines.  Is it, because they have electronic e-units instead of electro mechanical unit like what is it in my dad’s old engine?

@Roeschs1 posted:

Thanks for the feedback.  I will definitely do that.   If that turns out to be true, any suggestions for what I can do?   I am not having the same problem with my modern engines.  Is it, because they have electronic e-units instead of electro mechanical unit like what is it in my dad’s old engine?

Your modern locomotives likely have a different spacing of the pickup rollers (some even have a total of three or four pickup rollers under them now) so at least one is always in contact with the powered section of rail.  No power is no power, so the electronics won't have anything to do with that.  Your 726 as mentioned above, sounds like its pickup rollers are both landing on one of the plastic, non-powered, portions of the rail (which prevents short circuits when going through the switch when it is lined in either direction) which is preventing the motor, lights, etc from getting power.  When you go through it at 15 or 16 volts, the momentum carries it over the non-powered section and it's able to continue on its way.  Any slower and it just stops before it can hit the powered rail again.

About the best you could do aside from modifying the track plan to space the switches out is perhaps make a wired tether like some modern locomotives have to tie the power pickups from the tender to those on the locomotive.  That will give you one more set of pickups to help carry it through the switches.