Tuesday, 23 March 2021

Boat of Garten North Interlocking

 Boat of Garten North Interlocking 

21 March 2021



It has been a while since the last update, progress has been slow with the forever changing situations. Anyway progress has been made! A lot of time has been spent making up drawings to work from, in regards to the interlocking. It has taken a lot of drafts, emails and discussions with colleagues but in the end I believe we have a working plan for the interlocking for the north signal box. 

For those who do not know or understand what “interlocking” is. Basically it is what determines if the train can be signalled from signal A to signal B. I suppose you can call it a mechanical computer, only if the levers are in the correct position and have been pulled in the correct order will you be able to pull off the signal allowing the train to move.



Just a reminder for us all this is what we are working towards. Still lot’s to do but it will be good when it is all finished. 



This may not look like much but a lot of time and effort has gone into this, by several people! Each picture is one locking box. This is the diagram of what needs to be done to allow train’s to run safely preventing any conflicting movements and ensuring that the signaller can only do his job correctly.

We have been lucky to find some locking tappets in one of our store vans. Which have had the old notches cut off and new metal bar added, so they are as good as new! Other than needing cleaned and polished up they are ready for use. Thank you who ever took the time to do all this work in the past, it is much appreciated.


This is how we were looking after a day had been spent cleaning up the tappets. At this point the pins still needed cleaned up and pin holes skimmed out. This was all completed and they were taken back to the signal box at Boat Of Garten to be trial fitted.


With out the new tappets in, this is how the locking looks in the locking boxes. So what you can see in the top locking box is two channels for the locks to sit in. Thus allowing you to have up to four locks on one tappet if required. You can just make out the “locks” the “tappets” and the bars that hold it all together. It’s not the easiest to get a picture of because of its location and certainly not the easiest to work on.


Not the easiest thing to show in a picture but this is all the tappets that we require in the locking boxes. The locking boxes are of a Eastern Region design, on our Mackenzie and Holland frame. This was quite a common thing with the frames that had been sent to Crew to be serviced and prepared for the next signal box that it would be installed in.  The tappets are not straight, there is a curve half way along them because of the way the lever moves in the frame. Each tappet in turn needed to be shaped as required for a smooth movement from the normal to reverse position. After a lot of removing, shaping and replacing this was finally achieved.



With the tappets all in the locking boxes sitting ready for the notches to be cut to take the locks. It was time to start looking at making up the locking bars. Hear you can see a selection of the different shape locks and the bars that hold them all together. This is what prevents or allows the levers to be moved.



This is the first attempt of riveting the dies to the bars, not a bad attempt a lot has been learned and will see about doing it for real next time.

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