Model Railway Forum banner
1 - 8 of 8 Posts

·
Administrator
Joined
·
9,845 Posts
Discussion Starter · #1 ·
A question was posed as an aside in another topic "How do you wire a crossing". Since I do not believe that there is anything special required to wire a dead frog crossing, I have taken the request to refer to "live" frog crossings which do indeed need some care.

To answer the question, I have prepared this diagram in "Paint" to illustrate the following cases along the top row of diagrams:-
1) The four separate sections which make up a Peco code 75 crossing (left)
2) How the sections are wired for trains traveling from left to right (centre)
3) How the sections are wired for trains traveling from right to left (right)

The bottom row of images shows a crossing where entry to the "crossing route" is controlled by a pair of live frog points. In this case, the current to the crossing frogs can be switched by the point switch which is controlling the current to the point frog. In other words you don't have to buy any extra switches.

The three diagrams in the bottom row are as follows:
1) The sections which need to be powered
2) The sections set up for crossing - the train follows the black line (it's not 3 rail

3) The sections set up for through running



I do hope I haven't made any mistakes.

David
 

·
Registered
Joined
·
204 Posts
I have some live frog crossings set up so that the adjacent live frog points provide the power routing. On DCC this means that attempting to traverse the crossing with those points set the wrong way results in a short. I have decided to change the wiring to use a reversing unit to power the crossing frogs.
 

·
Administrator
Joined
·
9,845 Posts
Discussion Starter · #3 ·
>I have decided to change the wiring to use a reversing unit to power the crossing frogs.
Doesn't that become rather expensive?

An alternative might be to set up an ABC section in front of the crossing so that any locomotive traveling into the conflict zone will be brought to a halt before a short can take place. This of course assumes you have decoders with ABC, which I think means Lenz silver as a minimum and they ain't cheap either.

David
 

·
Registered
Joined
·
70 Posts
My problem refers to a short diamond insul frog scissor crossing that allows access to a loco shed from the run round loop. Theeres no problem until one of the straight line turnouts is out of sequence ie not all 4 to 'crossing' or not all 4 to 'straight ahead'. Will repost soon with more detail if needed, in the dreaded grip of SWMBO riding her 'decorating horse'!
 

·
Registered
Joined
·
204 Posts
QUOTE (dwb @ 27 Jan 2007, 22:32) <{POST_SNAPBACK}>>I have decided to change the wiring to use a reversing unit to power the crossing frogs.
Doesn't that become rather expensive?
£20 each. Fortunately I only have two of them.
 

·
Administrator
Joined
·
9,845 Posts
Discussion Starter · #8 ·
>Scissors crossing
I have one of these but it's live frog. I am only switching power from one set of points. At a guess, I think you will have to isolate the crossing and supply power separately regardless of the fact that it is dead frog. Or maybe you just need to isolate the crossing from one pair of points but still switch all four regardless.

>Forgot to say...amazing drawings!
Thank you. I use the Windows "Paint" program and draw them pixel by pixel at 800% zoom with the "grid" switched on. The rest is simply a case of making sure things line up and the proportions look correct. "Cut and paste" does make like easier.

I found an interesting use for the "Flip" function yesterday. If you make your switch symmetrical, then you can use "Flip" to change it one way or another.

If you have single pixel connections between different parts of a frog, a single "Fill" action will change the colour of all parts.

David
 
1 - 8 of 8 Posts
Top