I've attached a layout plan I am working on and am trying to identify reverse loop situations - is there only one and is it identified correctly?




(This is an attempt to do Layout 27 from Marklin's HO layout book 0700 using MTL Z track - with 8993 reversing sections from Marklin used where needed. I've left out elevations, sidings, yards, etc. I am considering MTL track because it appears more durable for my "multiple connect & disconnect" style of layout building. I should add that I used to have an M track layout 20 years ago and really liked the robustness of the M track.)

Thank you.

Dan

Lars,

Thank you very much. Just so I'm sure I understand this, if I use the Marklin 8993 three track sections just above the words "reversing loop...", that is coming out left from the straight section of the switch, there will not be any short circuiting problems?

Dan

The 8993 just requires the 3 track sections. In operation, the engine will stop half way along the 8993 track section, and you will have to turn your controller in the other direction to re-restart the engine. Be aware that while it works well for single engines, it doesn't work so well for large rail cars (i.e. Flying Hamburger or old ICE) They stop and don't restart until manually moved off the 8993 track section. This is probably what Lars is refering too.

Mark.

Don hi,

I don't think the section you refer to is called a "reverse loop", it is a figure of 8.

Cem.

Hi Cem.
The term 'reverse loop' is misleading here. the lower set of rails (three straights) in the box are, functionally, a reverse loop inasmuch as they reverse the direction of travel if you return to the outer loop.

Chris.

I would like to thank everyone for their help. I think I will get rid of the switch (and its connection to the "inner loop") on the far left of the layout. The effort (& cost) to eliminate short circuit possibilities by using 8993 or soldering diodes for a relatively minor aspect of the layout seems excessive. Again, thank you all.

Dan

Pete,

Are these the Atlas Snap Relay's? or their Controllers? or both?

Thank you Dan

There seems to be two topics on this subject, not sure why. Anyway, here is my post from the other topic. The second link shows how the relay fits into the scheme of things.

NB. If you did go for the relay option, you would have to remember that the controller now acts as a cab control (as in 3-rail systems) and not as a direction control. I see this as a possible source of confusion for all but the simplest layouts with only one or two locos running.

The two images I posted are:
http://trains.manvell.org.uk/misc/ReverseLoop1.jpg
and
http://trains.manvell.org.uk/misc/ReverseLoop2.jpg

All the best,
Chris.

Dan, Ozzman explained it perfectly and the second diagram Chris posted does show how it works - but it does look complicated. If you do use this method you would need to ensure the supply to the relay is within spec, but the track voltage is less critical - as long as your not running more than about 16v, I would suggest. The control supply is independent of the track supply. I'm not sure why Marklin stopped selling the relay's, perhaps the wiring method isn't really conducive to anything other than a permanent layout!

The loop in itself wasn't a bad idea, since it is always nice to have a place where the trains can change direction on the layout. But I think it needs to be a little longer to enable automatic reverse loop operation. The Märklin 8993 track set allows only one direction of travel, which makes the loop less useful.

Another solution is to isolate the "loop track" from the main power circuits, and connect it through a 2-pole momentary switch button. You have to press the button to get power in the track and when you are in the reverse loop you set the other power circuit in the desired direction and speed before you enter it. Then you can have another button (or even better a 2-way switch) so you connect the loop track to the second track. It does the same job as a solution with relays, but you need less parts and it is probably more reliable. Well, of course there is always a risk that someone pushes the button the wrong way and get a shortcut, but that's what we use fuses for...