bachmann reverse module

[schalike]

 hi to all,my name is volker and i am new to this forum.i live in calgary,alberta,canada.i started a tt gauge (between  "n" and "HO")recently.all my track ,turnouts  and rolling stock is older "EAST GERMAN" material.i purchased Bachmann Dynamis and  equipped 3 loks with decoders.everything thing runs great until i added two return loops to the layout.the 2 bachmann reversing units operate ok most of the time however every now and then the lok will stop as it enters or  exits  before or after the GAP.does anybody have any idea why this would be.i do not believe  it to be the  metal frogs(powered.)thank's volker
  "ENJOYING THE FORUM A LOT,BUT I AM NOT HO NOR N BUT "tt"

[Jim Banner]

Hello Volker.  It is good to heard that TT gauge is alive and well, and living in my old home town (I hope the blizzard missed you!)

DCC reverser modules do not generally cause locomotives to stall, and when they do, the locomotives usually stall right at the gap, not before or after it.  I am guessing you have your gaps right at the ends of the turnouts (track switches) so that it is difficult to tell whether the stall is the fault of the turnout or the fault of the reverser module.  If you moved the gaps one or two sections of track away from the turnouts, it would be much easier to tell where the fault is.  After your testing, you could move the gaps back to their present locations if their new locations left you a loop less than a train length long.

It would also be helpful to know a bit more about the locomotives that are stalling.  For example, if they are 4 wheel steam locomotives, they can still have problems at turnouts even though the frogs are powered.  When installing decoders, I have sometimes had problems with wheel pickups not contacting the wheels properly after I put the locomotive back together.  This can reduce the number of wheels picking up power from the track and cause stalling at turnouts, even when the wheels and track are clean and all the parts of the turnout are powered.  This is because there are places in turnouts where not all wheels are on the rails all the time.  I do not have much opportunity to work on TT trains, and do know how the electricity gets from the wheels to the motors in your locomotives, but if you check, you might find a problem in that area.

[schalike]

thank's jim.we are still in the blizzard,so i put the golf clubs away again however i was too lazy to get the downhill skis out of the attic ones more.so it's TT modeling,not such a bad activity either,EH?so jim my gaps are  about 10" away from the  turnouts and the lok stalls  as it enters the loop.i.e.at the gap and as it leaves the loop also at the gap.but never both at the same loop.what puzzles me is that this only happens sometimes and seems  worse when the  lok runs backwards.i run a brand new taurus from piko with 8 pin decoder.the lok was dcc ready.i'll check the pick-ups,they are 8 wheels 2 are offset traction wheels and all have contacts.one loop is actually a cross-over or an oval with a diagonal gapped isolated section.i might have done this wrong??the gaps are only in the straight inside section?i have also tried adjusting the amperage at the modules with no real resultd.these are now set between the 1 amps and 2 amps .volker(is the  + - feed to the loop section important)

[Jim Banner]

The feed to the loop can be hooked up either way.  If it is reversed, the reverser will take care of it.  That is what it does.  But the input and output cannot be interchanged.  That is, the output connections must go to the loop and the input connections to the main track (the track which connects to your  Dynamis.)  The wiring must be heavy enough to carry the full short circuit current of the Dynamis or the reverser will not throw properly.  And the short circuit path, which may be from one wheel to another on the same side of the locomotive, must have low enough resistance to carry the full short circuit current of the Dynamis or again the reverser may not throw properly.  Also, take a look at the gaps themselves.  If there is some sort of insulator between the ends of the rails at the gaps, make sure it is slightly below the tops of the rails so that a wheel rolling across the gap can drop down slightly and touch both rail ends at the same time.  File or carve out a bit of the insulator if you have to.  If you do this for all four of the gaps in each loop, you will get a cleaner short circuit entering and leaving the loop.  Hopefully, better shorts as the wheels roll across the gaps and heavier wiring if needed will take care of your problem.

[schalike]

thank's jim,i have changed the power feed to the reverse modules fro the bachmann dynamis controller to the main trunk directly and seperately to each module.this seems to help however sporadically one loop control fails.i think you hit the nail on the head by pointing out the importance of the gaps being exactly identical in order to have BOTH wheels hitting the short at the same time.mine  are not that well cut especially on that one spot.so i will work on it and report back.i am also thinking that my  set up may be unorthodox as i  have 2 contact rails for each loop which operate the turnout as the train  crosses the section(activated by a lok wheel ).the problem might be that i have one  cotact track inside the loop and one outside the loop.this might "confuse " the module??this setup makes the operation fully automatic and also lets the train enter the loop ,once left,once from the right without  my intervention .how do you operate the turnouts on the loops?volker