A Question of Logic

I've had my thinking hat on again, in another attempt to synthesize Lanrhaiadr Mochnant and The Art of Compromise to produce a version that won't take up too much space in the office.

Point rodding in blue

Compared to earlier versions I'm planning to swap the viewing side over, so the goods shed will be at the front, as it is on Apa. Compared to the real LM the big changes are the replacement of the level crossing with a bridge and moving the main platform  to the down side of the loop. A quick reminder that in any case the model is going to be set both after passenger working ceased in 1951 and after LM became a terminus in 1952. Changing the level crossing for a bridge means I have to decide where to put the motley collection of sheds and the weighbridge. I suspect I won't reach a final decision on that until I place some mock ups on the baseboard. I don't think there is actually an obvious on scene location for the weighbridge that makes sense . A couple of other bits of the jigsaw have now fallen into place, including where the iron mink stood that was used for additional storage in the yard.

The jigsaw I'm not so sure about involves the points and signalling, because some of the edges of the puzzle are missing. Literally so when it comes to photos.

You might need a pen and paper for the next bit....

What I do know is that the LM lever frame had twelve levers, and Mike Lloyd records ten of them being in use at some point in time. I'm fairly certain that four levers were for signals. I know that three sets of point rodding ran along the downside of the line and I'm presuming two of those operated the points at 7 and 8. I'm guessing that point 8 at least had a facing point lock, which could account for the third rod, though the onlyTVR  FPL I have a photo of, at Llansilin Road, appears to have been operated off the same lever as the point.

Is it possible that point 7 didn't have a FPL because passenger trains wouldn't have used it in the up direction, or would it have had an economical FPL? In that case though wouldn't the FPL' for points 7 and 4 have been of the same kind, so why would they need rods from the lever frame?

Two rods pass under the loop, one of which then runs along the down platform towards the cattle dock siding. I think this continues to the catch point on the cattle dock siding. The second one, I presume, controls the catch point on the goods shed siding.

Three sets of rodding run alongside the up platform. One crosses under the loop at the end of the platform and controls point 5, so I'm guessing the remaining two control point 4 and its FPL.

That by my calculations comes to eight sets of point rodding, and four signal cables.

So the next question is what levers would have controlled what, and how would the interlocking have worked. Using TRAX 3 this is my best guess so far

It seems to work for most of the obvious movements and conflicts I can think of. When/if I get around to building it I'll be using DCC so at least I'll be able to amend things. Any advice and observations at this stage though would obviously be more than welcome.

Signalling Diagram

In the absence of a signal diagram for Llanrhaiadr Mochhnant I thought it would be relatively easy to convert the signal diagram of Llangynog. Here's one I did earlier.

It seems my Photoshop skills are a bit rusty, because it has taken an hour and I really need to start again.

So I did, this time using Anyrail to produce the basic diagram. This is just the basic export tweaked in Snapseed. The next step will be to combine this with the text from the version above, and another version with the switches in yellow so the blue indicates the alternative route. And here we have the finished version:

Why am I doing this? Well I'm enjoying the challenge, of course, but if I ever do build LM it would be useful supporting material for display with the layout. The main reason I'm doing it though is actually to check that I've got the point rodding arrangements right. I think I'm now pretty sure what went where now. Well almost, I'm not sure if I'm right in putting a facing point lock at the up end and that there isn't a second catch point to protect the running line from the loop at that end. What I do know is that there are two sets of point rodding running in that direction.