Reverse Loop

[simonjk]

Hi,

 

I am looking to add a reverse loop with some storage loops to my layout.

 

I’ve attached a diagram showing what I am adding.  The yellow and blue lines are the rails on a single piece of track.  Only one train will run at once either into or out of the loop.   I’ve not shown all the storage loops in the loop for clarity.

 

I have a NCE Powercab.  The stock to be stored in the loop will include Hornby 125’s with lights and sound in the power cars.  All my locos have lights and I have a couple with sound.  Don’t have any stay alive fitted to the DCC decoders.  I’ve no lights in any coaches.  Stock is all modern. 

 

As I will be storing stock in the loop I was hoping to isolate the rails A and B.  This section of track is 100 inches and longer than the length of my largest train, the 125 with sound and lights.  I also believe I will need to isolate at C and D.  This will be a short section around 18 inches.  I have marked W,X,Y&Z as alternative isolating sections but I don’t think I need to do it this way.

 

I assume I will need two auto reversing modules. 

 

Also I am going to be using PL11 motors for ease of access.

 

What I’d appreciate some advice on is

 

• Does this look ok and vaguely sensible?
• Any advice on the best module for a Powercab ?
• Do I just have 1 feed in the isolated sections?  A & B will be 100 inches and therefore made up of several pieces of track.  Normal DCC practice would be for several  feeds but I am not sure if this will affect the operation of the reversing module ?  Or do I wire a connection between the end of each piece of  track to aid connectivity?
• Have I missed anything?

 

Thanks in advance for any advice.

 

Simon

 

[Nigelcliffe]

Here's one approach, which uses one auto-reverser, with the following constraints:

 

1 - Only one train may pass through the red/green area at a time.

2 -  The train must be shorter than the rail path.  From the diagram, the shorter paths appear to be (2 to 4) or (2 to 1), these need to be longer than the longest train in use. 

 

Breaks in both rails at places 1, 2, 3, 4.  The Red/Green rails fed by auto-reverser.   The storage loops are fed by same track polarity as the main layout, and its only the junction area (red/green) which is switched by an auto-reverser. 

 

[simonjk]

Thanks Nigel,

 

Interesting solution but unfortunately path 2 to 4 isn't long enough.

 

Simon 

[Harlequin]

You could move place 4 further round the storage loops to make path 2 to 4 long enough but remember that path 4 to 1 must still be shorter than a train length.

 

[Nigelcliffe]

 

 

 

48 minutes ago, Harlequin said:

You could move place 4 further round the storage loops to make path 2 to 4 long enough but remember that path 4 to 1 must still be shorter than a train length.

 

 

Has potential, if the gap at 4 is moved to the far end of the storage loops, and the gap at 1 can be moved back towards the main layout.   But, the path 1-4 has to be long enough, as does the other paths, and no chance of a parked train bridging any of the gaps.

 

 

If that doesn't work, then a solution with two reversers is to invert my plan.   Power the Red-Green normally from the system.  Fit main layout with one reverser.   Fit storage sidings with second reverser.    I think that works, even if the paths through the Red-Green area are shorter than the maximum train length.

 

 

 

 

- Nigel

[simonjk]

Hi,

 

I can move 4 further round the loops  and move 1 further right so it's right by the points. But that would make 1-2 less than a train length. Which I think just moves the problem somewhere else.  I shouldn't have bought that extra MK3 for my 125 set !!

 

So if I am  going to continue with this plan I need to consider Nigel's second suggestion of inverting.   Can I just clarify a few points on that if you don't mind ?

 

• Cut the track on both sides at 1,2,3 & 4 and fit insulating joiners. 
• Power the Red-Green normally from the system - Take the power for this straight from the back of the power cab track output and use as a feed to the Red/Green track.
• Fit main layout with one reverser -  So take the power from the back of the power cab feed and into the 1st reverser.  Then the output from the 1st reverser into the existing DCC track power bus I am using for the layout.  This will power the existing layout.
• Fit storage sidings with second reverser.    So take the power from the back of the feed and into the  2nd reverser.  Then the output from the 2nd reverser  and feed to the storage loops.

 

just want to make sure I understand it before I spend any money on the track, DCC modules etc.  

 

Thanks for your time.

 

Simon

[John ks]

Here is another possibility

The drawing is turning into a dogs breakfast but I think it still works

 

 

You will need 2 DPDT relays or switches 1 & 2 controled by points 1& 2

Point 2 controls switch 2 which determines the polarity(phase) of the red/green section

Point 1 controls the polarity(phase) of the orange/brown loop

Disadvantages

1 the contacts on both switches/relays need to carry the full current to the red/green, orange/brown sections

2 when the points change there is a slight interruption to the power in the red/green, orange/brown sections which may cause sound locos to shut down & restart

Advantages

Train lengths are irrelevant. Because the points set the polarity(phase)& trains can only go where the points are set to. (unless I am missing something)

The red/green, orange/brown sections are not connecter to the main DCC bus.

John

[Nigelcliffe]

I was about to suggest something similar to John KS above.   If relays are used, then they probably switch fast enough to not drop power to sound locos, but only experimentation will show if that is an issue.    If the turnouts have an option to fit switches to them (or whatever switch gear operates the turnouts) and those operate relays, then this is a cheap and reliable method.    Suitable relays can be bought ready-assembled onto small circuit boards, with screw connections for various wires through Ebay, Amazon and other sources for very little money.

 

The sound drop issue may be a non-issue as for off-scene storage, many people would run the loco through the scene-edge, then turn off the sound whilst running, bring loco to halt.  To return the loco to the visible scene, start silent loco running, and turn on sound just before it comes into view.

 

 

[simonjk]

Thanks John and Nigel.  I think this looks like a great solution.  The sound won't be an issue as I will be turning it off in the loops as they are for storage.  I can set the route then start up the sound and sort out the lights etc before driving the train off and onto the scenic part of the layout.  Also I'll only ever be driving the one train into or out at anyone time.

 

From what I've read I'll need latching relays.  As they'll be taking the power for the track I'll need one  rated for up to 24V and I guess around 5 amps in case I ever upgrade my powercab to something more powerful.

 

I'll want to control them from the switch I used to operate my point rather than adding a switch on the point.  My points motors are solenoid and controlled with SPDT switches with the center being the off position.  

 

I tend to use Rapid electronics for my electrical bits.  I wondered if something like this would be suitable https://www.rapidonline.com/te-connectivity-rt424f24-dpdt-pcb-relay-24vdc-8a-latching-dual-coil-54-5972

 

What I am not sure about is the point motor part is DC where as the DCC track power is AC and if this needs to be taken into account.  Also I am not quite sure of how to link the switch and the switch element of the relay.  I think I understand the DCC track part of the relay.  Any advice on that would be great.

 

Once again thanks for your help and it's really appreciated.

 

Simon

Edited August 3, 2019 by simonjk
correction reqd

[Nigelcliffe]

Simon,

the "24v" you've quoted on that relay is the coil voltage, not the switch capacity.  The specification for the relay (and its cousins with other coil voltages) is contact switch of 250V and 10A, so massively more than you need for DCC switching purposes. 

 

The relays will also need some vero=board or similar to fix them to - attaching wires directly to the pins isn't sane, whereas a bit of Veroboard will make it fairly simple. 

 

 

The coil voltage choice, and whether any other components are needed, will depend on how you are operating the turnout motors - what is the power supply for them ?   

You say they are Peco PL11's with centre-off biased SPDT switches. 

 

 

- Nigel

 

 

[simonjk]

Nigel,

 

Just been to check and I am using a transformer outputting  16V AC.  

 

I was  going to use centre-off biased SPDT switches, like I do for the existing points, but as I've not bought anything yet I can change if reqd.

 

Did plan on using PL11 due to space restrictions but I've had a look and I think I could use surface mounted PL10's.  Again nothing yet purchased.  This would allow use of something like a PL-15 Microswitch.  But I think I may be happier controlling from the switch not the point for reliability, although open to suggestions.

 

Thanks.

 

Simon

[Nigelcliffe]

Simon,

 

option 1:   using the 16vAC supply, centre-biased SPDT switches and PL11's.  

For this, need the latching relay (probably the 12v version of the one you identified), some vero-board, and means to rectify the AC to DC for the relay coils (a few diodes).  The relay is 2.54mm pin-pitch, so will mount on vero-board easily.  

 

option 2:  use the PL10 plus PL15 switch.  Could use the PL15 switch directly - there is a bit of a risk of loosing the DCC power for long enough to re-set a sound loco, or a moving loco, but if all locos are stationary with sound turned off when the switches are operated, then it will be fine.   

The PL15 has a pair of contacts, so you'd need two PL15's attached to turnouts #1 and #2 in John's diagram above.   Its by far the simplest option for someone not comfortable with electronics, and may be the cheapest as well.   

The posh optional version of option 2 is to use the PL15 switch to operate a DPDT relay.  That needs a couple of relays, one for each switch assembly (simpler to buy them pre-populated on boards from numerous sources than to solder them up), and either 12v or 5v DC to power the relays (select appropriate voltage for the relays).  Has advantage of faster switching time than the PL15, so sound locos and moving locos probably don't notice the change-over happening.  Could be retro-added later if it proves necessary.   

 

I can think of other options, but decided to not complicate things further.

 

 

If PL10+PL15 switch (option 2) will fit your track, suggest you try it and see if it all works.  Its cheap, simple, and may do all you need. 

 

 

 

 

- Nigel

 

 

[simonjk]

Hi Nigel,

 

I shall give option 2 ago and see if it works.  If not I can always try the relay option.

 

Going to be a while as I need to build the baseboards etc for the new loop.  I'll put an update on at some point in the future as it how it's gone.

 

Thanks to both you and John for your help on this.

 

Simon

 

[simonjk]

Hi,

 

Just to say that I've done this using PL10's and PL15's and it works a treat.  Sound on my TTS locos doesn't cut out  when I switch the points and all the other DCC loco's are fine.  I've just got to be careful the points are correctly set and I don't change them until a train and entered or left.

 

Thanks again to everyone for the help.

 

Simon