Two Train Operation



 Bruce's CK Holiday


Two Train Platform Modifications:


Now that you have two trains you need to get them to coexist on the same track.  Unfortunately, any two trains (especially Bachmann’s) operating on exactly the same voltage will operate at significantly different speeds.  So, if you just put two trains on the same track one will eventually catch up with the other and they’ll crash into each other.  To keep them from colliding you need to implement some form of speed/distance control on the track.   


While we’re discussing Train behaviors, there’s another visual problem to address with the Main Street Platform trains.  To make the train experience “look right” the trains should stop at the Main Street Station to exchange passengers as they do in the “real” park.  Having the Train rush through the Station without stopping just doesn’t look right.  So, as we implement the two train system we should also figure out how to have each train stop at the Station as they travel around the platform.  Fortunately, this is easily done with the Two Train design. 


I admit that I’m not a train guy, but with a little Internet Research I found the easiest way to keep the trains separated on the Platform Track is to have each train stop at the Main Street Station, wait there several seconds until the other train reaches a certain part of the track (past the Castle), and then have the train stopped at the station resume operation around the track.  This maintains a safe and consistent distance between the trains and prevents collisions.  Having the trains stop at the Station also adds the desired element of realism to the train behavior.  The following video shows how it looks: 


Two Train Operation Video:


Click for VideoI've tried to video the operation of the two trains on the Platform Track, but it turned out to be harder than I expected.  Capturing two separate vehicles traveling in different places at the same time and making it make visual sense vastly exceeded my novice video skills.  And, my camera wasn't sensitive enough to show how the lights look at night.  But, the video should give you an idea of how it all looks.  Click this text or the photo to start the video. 



This is a fairly easy modification to make to the platform if you have electrical/electronic expertise.  Here’s how the Two Train Electrical modification is done: 


1)  Install the Track using the “look” that you like, either Beveled or Flat, using the Artist’s instructions but with the following modifications: 

A.)      After you have the Cork installed and before you lay down the track install two Magnetic Switches like these in the track at the locations shown in the Photo by drilling a hole through the cork and down through the platform.  These can be purchased at larger Electronic Supply stores such as Fry’s.  You can also buy unpackaged Magnetic Switches at Train Stores, Click to EnlargeClick to Enlargebut IMHO they aren’t quite as easy to install. 

B.)      As you connect the track sections together, electrically isolate the outside rail of the track in two areas by creating a “gap” in the outside rail of the track at the locations shown in the Photo.  The idea is to leave a small gap between the rail sections that electrically isolates the track sections but does not create a very large gap – a gap the size of 5 or 6 sheets of paper should be plenty.  Do not use a track connector at the “Cut/Insulate” point.  This creates two electrically isolated “Blocks” of track – one in the proximity of the Station and the other around the rest of the Track Loop around the Castle.  

C.)       Install a second set of power supply leads to the “Station” Block of the Track.  (You’ve already installed power supply leads for the rest of the Track Loop around the Castle when you followed the Artist’s installation instructions.) 

D.)      Even if you’re not going to run two trains right away you might want to make these modifications as you’re laying down your track.  The modifications can be made after the track is installed, but it’s easier to do as you’re installing the track.


2.)  To make the trains slow down and stop and then start up slowly and smoothly you’ll need to purchase and modify a Train Power Supply with “proportional tracking” and a 15-30VDC output.  You can’t use the Bachmann controller unit that came with the EP Ripley because it modulates both rails and makes the electrical isolation more difficult.  I used an “MRC Tech 3” unit which was overkill, but worked fine.  It cost about $80 list.  Here is the modification I made to the Tech 3 unit:

A.)      The unit came with Momentum control (smooth starts/stops) which I intended to use, but it operated far too slowly for the Platform.  So, we need to implement our own momentum control.  I’ll talk more about this modification in Step 4 below.

B.)      If you’re going to fit this controller up inside of the platform like I did then you’ll need to chop down the casing from its original 4” height to the 2.5” required to fit up inside the platform.  It should be fairly obvious how to do it but send me and E-mail if you need advice.

C.)       The Track output from the Train Power Supply will connect to the Station Block of track.

D.)      The DC output from the Train Power Supply will power the two DC regulators described in Step 4 below.


Magnet3.      Buy some magnets like these from your local hardware store.  Initially place one magnet in the last car in each of the two trains.  At this point it doesn't matter exactly where you locate them because we’ll Click to Enlargefine tune the locations of these magnets later in the instructions.  Here's where I placed the magnet in the Caboose of my CK Holiday.  It's the round thing under the cab.  The magnet is held in place by its attraction to the metal weight in the car.


Regulator4.      You’ll need to purchase and build two cheapo DC regulators like this one.  They cost about $10 each and take about 10 minutes to assemble.  You can use the DC output from the Train Power Supply as the input to drive these supplies.  The outputs of the two regulators will provide adjustable DC power at about 5 watts for the rest of the track loop around the Castle and provide 12vdc at 5 watts for the Block Controller (described next)


5.      To build the Block Controller you’ll need to purchase two 12vdc DPDT relays, a linear potentiometer, an electrolytic capacitor, and two 1 amp 12vdc diodes.  These can be found at your local Radio Shack or Electronic Supply store.  They’ll cost about $20 all together.  Here’s what this stuff does:

Train Power Supply and Electronicsa.      The Relays are connected to the Magnetic Start Stop Switches placed in the track in Step 1.  When the Station side switch is toggled it sets the relays to slow down and stop the train in the Station Block by activating the RC circuit discussed in step “b” below.  When the Castle side "Start" switch is toggled it tells the relays to start and speed up the train in the Station Block.

b.      The Pot’ and the Capacitors form an RC circuit to tell the Train Power Supply how rapidly to slow down and speed up the train in the Station Block.  The exact values of these components depend on the Power Supply used.  I found that for my MRC Tech 3 a 5,000 uf cap and a 5k ohm pot worked well when wired in parallel with the Power Supply control Potentiometer.  [FYI, these modifications will likely void the warranty of your Track Power Supply.]

c.       The Diodes are put in series with the track power supply leads to prevent feedback between the track power supplies as the train tender contacts traverse the gap between the blocks.  Be careful to connect the Train Power Supply common leads to the inside track rails and place the ‘hot” lead of the Track Power Supply (discussed in step 2) and the output of the DC regulator (discussed in step 4a) to the outside rails of the Station and Castle blocks respectively via the series diodes.

d.      How to connect all of these components together will be fairly obvious to electronically skilled hobbyists, but send me an email if you need help.  If there's enough interest I'll post the schematics.


6.      As an option you can install and connect a Block Light Tree like this [Photo] to the Block Controller add a bit of extra realism to the track.  It will light “Red” when a train is in the Station Block symbolically warning the other train to stop and the lights will turn “Green” when the Station is “Clear”. 


7.      Here are some tuning tips for the Two Train Setup:

a.      Start out by operating the Castle side Block at about 5vdc.  At that voltage the trains move fairly slowly and look pretty realistic.  Much faster and you risk collisions and the starting/stopping at the station appears rushed.  Much slower and sometimes a cold train won’t start up (the Bachmann’s get cranky when they’re turned off for very long). 

b.      Set the voltage of the Station side Block regulator to match the speed of the Castle side block as the trains enter/exit the block. 

c.       Set the RC “momentum” potentiometer such that the trains both slow down and stop at the station at the roughly the right point.  You will “fine tune” the stopping location by adjusting the voltage of the Train Power Supply and moving the magnets around per the next step. 

d.      Move the Magnets around in the trains so that both trains stop at more precisely the same spot at the station.  The RC circuit and Power Supply settings will get you close, but the individual trains will run at different speeds so you have to use the magnets in each train to get them to stop in the right place at the station. 

e.      Realize that the little Bachmann engines run faster as they warm up and that as the trains warm up they’ll take longer and longer to stop and they’ll gradually stop further and further down the tracks of the station.  My trains take about 45 minutes to reach their maximum stopping distance.  Consider this when tuning your trains for stopping at the spot you like.


I know all this might sound a little daunting, but altogether this electrical modification should only take about 4 hours to perform once you have all the pieces.  Even if you only have two of the Bachmann Prairie Flyers (which are almost the same as the Disney EP Ripley) the impact of having two trains running in the park and stopping at the station is worth the effort.  Maybe if there’s enough interest we can convince Olszewski to mass produce this Two Train electronic package? 

Bruce Richards