Planning a layout - changing loco direction

[PJ_model_trains]

Due to limited size board I don't have room for a turntable but have lots of sidings coming in from clockwise and anti-clockwise directions. I therefore plan to install a cross over through the middle from bottom left to top right right of the oval which

 

will mean the train changes direction therefore the live neutral feed will also conflict. How do I get round this? What are the options?

[RDS]

@PJ_model_trains

I don't have one myself but I believe that the reverse Loop Module (R8238) is what you need to allow the polarity to change. I think it is normally used to go across the middle of a layout from one side of the layout to the other, in

 

effect turning the train around.

There are some details of it on this website, under DCC accessories.

[Fishmanoz]

Yes, you will certainly need the RLM. Check out the detail on Brian Lambert and remember you must include an isolated section longer than your longest train - yes train, not loco.

[PJ_model_trains]

Fishmanoz said:

Yes, you will certainly need the RLM. Check out the detail on Brian Lambert and remember you must include an isolated section longer than your longest train - yes train, not loco.

I looked under Digital/Accessories

on the Hornby site and saw the Hornby DCC Reverse Loop Module R8238 but it says on it 'Select' or 'Elite' not RailMaster, I take it is because it was manufactured before RailMaster but still works with RailMaster. It says... The Hornby Reverse Loop module

controls the polarity of the track so that locomotives running around these sections can do so uninterrupted without the use of switches and complicated wiring. Can only be used with the Hornby Digital units.

Regarding 'remember you must include an

isolated section longer than your longest train - yes train, not loco' are you saying train and tender or as I think Train, tender and all carriages?

I will check the Lambert site also. Thanks

[PJ_model_trains]

Fishmanoz said:

Yes, you will certainly need the RLM. Check out the detail on Brian Lambert and remember you must include an isolated section longer than your longest train - yes train, not loco.

Interesting... I expected to

isolate the section of track after the points on entry to the loop and before the points on exiting the loop. Brian Lambert recommends two isolated sections but then links them.

http://www.brian-lambert.co.uk/DCC.htm#Reversing%20Loops.

See: DCC

REVERSE LOOP where the loop does not return back to the same point.

What does he mean by 2x IRJ's? I was going to use plastic fish plates to both lines at either end 4 in all. Is this sufficient?

[idlemarvel]

Yes the Reverse Loop Module works with Railmaster.

FYI an IRJ (insulated rail joiner) is the same thing as a plastic fish plate.

[PJ_model_trains]

idlemarvel said:

Yes the Reverse Loop Module works with Railmaster.
FYI an IRJ (insulated rail joiner) is the same thing as a plastic fish plate.

[PJ_model_trains]

idlemarvel said:

Yes the Reverse Loop Module works with Railmaster.
FYI an IRJ (insulated rail joiner) is the same thing as a plastic fish plate.

[Fishmanoz]

The reason you need 2 isolated sections is that your crossover arrangement actually forms 2 reversing loops, and you need one for each. In Lambert's first simple loop, there is only one isolated section.

 

Yes, the isolated section must be longer

 

than the whole box and dice, loco, tender and carriages. Think about how it works: every time you drive a loco from main track to loop and vice versa, and each of these is opposite in polarity, there is a short created as soon as the loco wheels bridge across

 

the IRJs. The RLM senses this and, in very short order, switches the polarity and removes the short. But if the other end of the train is still bridging across the other end of the isolated section because the section is too short, then the switching of the

 

polarity causes a short at that end. So the RLM will switch the polarity back, and then back again because the short is now back at the first end, etc.

 

But only the loco and tender have pickups you say, it doesn't matter what happens at the carriage

 

end because the carriages won't bridge anything. Unfortunately, that is not always true, although it may be sometimes. Think carriages with pickups for lighting, like Pullmans, or double-ended modern trains with decoders for directional lighting in the dummy

 

car.

 

So good practice says to be certain with reversing loops, make the isolated section longer then the longest train. If you don't, the chances are you'll come to grief at some stage.

[Fishmanoz]

By the way, working with RM/eLink as opposed to Elite/Select? The RLM doesn't know and doesn't care what controller is being used. All it does is sense polarity reversals between the 2 parts of the track it is connected to, and swap the polarity in the

 

output part in the isolated section to get rid of that polarity reversal. So yes, it works with anything.

 

And for those who have a problem with non-DC and polarity reversal, just substitute phase for polarity, with phase reversal being 2 signals 180

 

degrees out of phase! and that should solve your problem.

[PJ_model_trains]

Fishmanoz said:

The reason you need 2 isolated sections is that your crossover arrangement actually forms 2 reversing loops, and you need one for each. In Lambert's first simple loop, there is only one isolated section.

Yes, the isolated

section must be longer than the whole box and dice, loco, tender and carriages. Think about how it works: every time you drive a loco from main track to loop and vice versa, and each of these is opposite in polarity, there is a short created as soon as the

loco wheels bridge across the IRJs. The RLM senses this and, in very short order, switches the polarity and removes the short. But if the other end of the train is still bridging across the other end of the isolated section because the section is too short,

then the switching of the polarity causes a short at that end. So the RLM will switch the polarity back, and then back again because the short is now back at the first end, etc.

But only the loco and tender have pickups you say, it doesn't matter what

happens at the carriage end because the carriages won't bridge anything. Unfortunately, that is not always true, although it may be sometimes. Think carriages with pickups for lighting, like Pullmans, or double-ended modern trains with decoders for directional

lighting in the dummy car.

So good practice says to be certain with reversing loops, make the isolated section longer then the longest train. If you don't, the chances are you'll come to grief at some stage.

Very detailed reply which

I thank you for. I expected you to say current could be passed from carriage to carriage but the lighting arrangements and double ended trains say it all. Cheers.

I expected to isolate at the points in and points out giving the longest section so that's

fine and I don't expect any train to be longer than the gap between the two IRJs so that's fine also.

I notice the RLM is connected to the main line DCC bus and to the Isolated cross over link with loops to the isolated main line from the cross over.

I will have numerous sidings coming off the cross over link and would expect to isolate every one of them straight after the points. I would also expect to loop each one to the isolated cross over section. Would this be correct or does it not matter? The way

I am seeing it in my mind is when ever the polarity changes as a train runs over it the sidings match the same polarity. Trains running from the sidings to the isolated cross over link will run on the same polarity maintaining the only changes of olarity being

as the train enters the main line again. Hope this makes sense. Am I on the 'right track' as we say?

[Fishmanoz]

I think you have it right re the sidings. Only thing is there is no reason to isolate them from the crossover. You would only need to do that if a siding ran from crossover to main.

[PJ_model_trains]

Fishmanoz said:

I think you have it right re the sidings. Only thing is there is no reason to isolate them from the crossover. You would only need to do that if a siding ran from crossover to main.

Brilliant you have just saved

me a job. I am just starting my soldering, I am soldering the underside of the rail so nothing is seen but, I am having difficulty doing it without distorting the sleepers with the heat, I guess I am just doing it to long and going over it to make sure it

is a tight joint. I am getting there, glad I discussed the reverse loop isolation points and procedure before I got to far with the rails though ;-)

Thanks again for your help.

[2e0dtoeric]

It's not just loco's, or rolling stock with lights - most stock now has metal wheels.

Think how a switch works - it is two contacts separated by a space - move the lever, and another contact bridges the gap. So - each time a wheel bridges the IRJ gap,

 

it makes a switch, and drives the reversing module scatty!

[PJ_model_trains]

Fishmanoz said:

I think you have it right re the sidings. Only thing is there is no reason to isolate them from the crossover. You would only need to do that if a siding ran from crossover to main.

I have another thought before

I get to the installation of the cross over link rail which will be very soon as today I should have the basics laid for the outer loops (with isolated section).

I understand the reverse loop effect as the loco, tenders and carriages cross over it and

the RLM deals with these changes automatically. Thinking of this from a human point of view, a train runs on the main track, lets say left hand rail is the live feed rail as the train goes forward, it enters the isolated section linked to the RLM and flicks

it to match that of when the train entered the section. As if leaves the section and the train enters the existing main line section it reads the power line with the left line as the live feed which is now the reverse of what it was initially. I am assuming

the RLM controls and remembers this for 'each train' that uses the loop and forwards and reverse are still the same in RailMaster for driving the trains.

Back to the thinking as a human not an electronic gadget, if the loop changed as the train entered

and left it in reverse of what it was initially would this affect trains in sidings coming off the loop? I expect to have 8 or 9 sidings coming off the loop, I guess this comes back to does the RLM deal with this and Is forward and reverse the same in RailMaster.

Human logic says forward is forward but if reversed is reverse, so is forward still forward after the changes in the loop and every siding from the loop when a train is moved in it?

I just need to be certain before I wire this part. It is a major job

to make changes under the board as I am disabled and cannot walk very much or lift much, I rely on my wife to do these things for me. That was why I designed the board to go over a single divan bed, so that she can just remove the legs and up end it against

the wall, I do the wiring then she lays it back over for me. I can't wait to just sit there with my laptop and play and add the scenery and other items above the board one the brains are put in place.

I hope what I have typed above makes sense so that

I can get on and add the loop and sidings track then join the wiring to their correct locations. Thank you for your help.

[RDS]

@PJ_model_trains

With Digital, Forward is always Forward and Reverse is always Reverse, which ever direction you either point your loco or which ever way round you connect up your power to the track.

All sidings off your reverse loop will work just

 

the same as the loop they are connected to.

 

If you are using a bus system, ensure that the main feed is only connected to the main lines. The sidings (off the reverse loop) will take their power via the reverse loop device. If you do have a Bus system

 

for the sidings, ensure that it is only connected to track in the reverse loop.

[Fishmanoz]

PJ, the RLM doesn't remember anything about your trains and where they are. All it does is switch the polarity such that it is the same as the end of the isolated section over which a train is passing to/from the main line. So it switches one way at one

 

end, and the other way at the other. Consequently, whatever train it is, and whichever direction it is going, it continues with the polarity matched as it crosses the IRJs at either end. And without the direction changing, as RDS confirmed above.

 

Every

 

time that happens, the whole of the isolated section and all the attached sidings change polarity without affecting the direction for trains in there.

[2e0dtoeric]

With DCC, the power to move the loco, taken from the track, is AC. Only the chip in the loco knows which way is forwards, and it always goes forwards on demand.

So, as said above, it doesn't matter which way around the power is fed to the track from

 

the controller, unlike with the analogue dc system.

[PJ_model_trains]

RDS said:

@PJ_model_trains
With Digital, Forward is always Forward and Reverse is always Reverse, which ever direction you either point your loco or which ever way round you connect up your power to the track.
All sidings off your

reverse loop will work just the same as the loop they are connected to.

If you are using a bus system, ensure that the main feed is only connected to the main lines. The sidings (off the reverse loop) will take their power via the reverse loop device.

If you do have a Bus system for the sidings, ensure that it is only connected to track in the reverse loop.

There are two isolated areas to the main layout (looking from one end to the other)
1 - starting from just after the last points on

the right to just after the points on the other side this point being the entry to the loop across is also insulated making the half circle and entry point the first isolated area.
2 - starting from the entry to the cross over loop to the opposite corner

diagonally with another IRJ at this point just before entering the main inner line oval the train now facing opposite way.

Wiring will be installed as detailed on Brain Lamberts drawing mentioned earlier in this thread. The RLM input feed from the

main bus which feed the bottom oval of the inner loop and the rails to the isolation points mentioned above. The main bus feeding this are and all the outer loop and outer junction connections. The output from the RLM will feed the cross over loop section

which in turn will link this section to the far end outer half circle and the 12 other sidings in the inner oval.

I planned to loop connections from the isolated loop cross over section to every siding also.

I think / hope I have got all this

right ;-)

[Fishmanoz]

I think you have this right. As per Brian Lambert and what RDS said, you need 2 separate buses. The first is for the main line and is connected to your controller. The second is for both isolated sections and the sidings coming off them, and is connected

 

to your RLM output. These must not connect to each other anywhere.

[PJ_model_trains]

Fishmanoz said:

I think you have this right. As per Brian Lambert and what RDS said, you need 2 separate buses. The first is for the main line and is connected to your controller. The second is for both isolated sections and the sidings coming

off them, and is connected to your RLM output. These must not connect to each other anywhere.

Hi thanks for the prompt reply.

I have been careful to create three sections and add isolators between each, once I get the cross over and sidings

in, my third large order coming tomorrow ;-) and get them fitted I will have the board stood on end and marker the isolation points. First I will wire all the main line droppers to the main DCC Bus. I have a RLM coming tomorrow also and will then wire in as

you say, first isolation section to a mini DCC Bus and back to the RLM then the second isolated area (the cross over) again a mini DCC Bus for the part and back to the RLM. Finally I will pick up all droppers from the sidings in the isolated area and link

them to the appropriate DCC Bus also. MAGIC! 2-3 weeks ago and didn't even know what a DCC Bus was and had never soldered in my life!!!

I reckon approx. 3 weeks to the launch of the Majestic set DCC set which I am waiting for (based on approx dates

given to me) that gives me 3 weeks to get the rest done starting with 20 point motors. I used TrackMaster to design my layout, really easy to use and adjust any changes made when laying the track. I have the evaluation software RailMaster and this is also

designed to match my layout so once I get the license code in the Majestic Pack I can get started with coding and programming the track and locos. I already have the 2 locos in the list so things are coming together. Hopefully have the system running in December

and get some enjoyment for the hours spent preparing it all. Scenery and more trains etc will follow all part of the fun ;-)

[Fishmanoz]

Well done PJ! The fun will surely start when the rubber hits the road as they say, in this case steel on steel.

[RDS]

@PJ_model_trains

The progress you have made in the last few weeks is remarkable.

I agree with fishmanoz, well done!

[PJ_model_trains]

RDS said:

@PJ_model_trains
The progress you have made in the last few weeks is remarkable.
I agree with fishmanoz, well done!

My thanks go to you guys (and my wife, she doesn't know how many more times I will need access

to the underside of the board LOL)

Fishing was always my main leisure/interest but as mobility and health has worsened I am restricted where I can get to to fish with my powerchair. I have one place I go in summer but cannot risk the cold to hips and

back in winter so I needed something for the 'long winter days' and trains have always been an interest particularly steam trains. I am not totally immobile I can hobble short distances (to put a de-railed train back on track). Being very computer addictive

the new RailMaster suits me down to the ground combining model trains and computers is just brilliant. Or it will be when I get the new Majestic set and get started ;-)

Thanks again everyone for your help, (and comments), I will be back when track,

trains and accessories need programming but once I have sussed it out and done it once there will be no stopping me.

That reminds me... do you know what the track size is and how to program it in RailMaster, is there a thread for this or some other

web link?

[Bulleidboy]

2e0dtoeric said:

With DCC, the power to move the loco, taken from the track, is AC. Only the chip in the loco knows which way is forwards, and it always goes forwards on demand.
So, as said above, it doesn't matter which way around the

power is fed to the track from the controller, unlike with the analogue dc system.

I understand fully what you are saying, but on the Elite the track connections are marked A and B, so are the connections on the track terminals, and the connecting

wire supplied is marked so that the wire from the Elite A "should" go to the Track A connection. Are you saying you don't need to worry about this?