One of the features I propose to include on my next layout Glenmutchin is an interlocked lever frame. This is because one the most common “issues” now on Portchullin is driver error running signals or attempting to go over a turnout that is against it. Glenmutchin will be a much more complicated trackplan and there will be a fair number of signals on it, so we are bound to have more operator issues! The use of an interlocked frame is intended to be one of the means of controlling these – after all it is how the prototype did it!
Interlocking frames have been built before but they are not written about much – there are some pieces here:
if you want to look them up. Whilst is it possible to do this electronically (and people have) I decided I wanted to go down the traditional route of locking tappits, so that if the road was not set correctly, the lever would not work and you knew you had a problem.
Given that Glenmutchkin looks to be heading for a 45 lever frame, with a lot of interlocking I thought it would be a good idea to start on something simpler. Thus, I have concocted myself a simple layout with a moderate amount of locking; this is what I have gone for:
And this is the locking chart that I think is right:
If people out there think there are errors in this; especially the locking chart (locking logic is a bit mind twisting) then please pipe up as I will be building it soon!