Saturday 5 November 2022

Bomen Signal box interlocking


Bomen Signal box Interlocking - or - who is going cranky

When I was designing the future Wagga layout, I had anticipated incorporating my partially built 56 lever frame only for the Wagga station.  The station at Bomen though didn’t seem that important in the scheme of things, and I was not going to worry about this until the layout was constructed.

As it turns out, I have not as-yet been successful in finding a builder, who is willing to undertake construction of my train room.  So, projects that were on the back burner have advanced instead.

My picture of Bomen was after the signal box removal in 1983

Prototype Bomen

Bomen was a crossing loop, with some additional sidings.  Only the sidings for the meatworks stock yards were interlocked by the frame, the long siding into the meatworks, the siding into the canning factory, and the one for the leather works were on a simple ground throwover levers on the yard tracks 

Bomen’s signalbox according to Bob Taafe’s signalbox book, was relocated from Uranquinty around 1941.  It was situated on the southern side of the station.  The frame was 20 levers.

A picture from the internet - showing the signal box

After I had enlarged a small pixel image of the signal diagram which was used for the interlocking diagram, a far better resoluton image showed up.  Careful checking found an error - lever 10 was actually a catchpoint with signal attached, where Bomen frame as modelled, as this lever as a signal, with a catchpoint attached.  Shouldn't affect operation


Way back in 1982/3, the British magazine “Model Railway Constructor” ran a comprehensive monthly series authored by Martin Goodall, on constructing a layout based on the GWR station of Bodmin.   Parts 15 through 23 concentrated on signals, and interlocking.  Inspirational, as well as informative.  The parts dealing with mechanical interlocking were the best I have ever seen on the subject, and from the time I read the article,  I took an intense interest in this obscure aspect of modelling.

(copies of the articles are at the end of this blogpost)

Unfortunately, this interest started just after the NSW railways removed the signalboxes at Wagga, and Bomen in 1983. 

But, luck was on my side.  A fellow modeller, who had also seen the MRC articles, had actually started making interlocking machines in approx. 1/10 scale, using the principles of the MRC articles.  Then around 1990, the Defence department moved him to Queanbeyan, where I was living, and I got to know Tony.  Tony Kociuba’s layout Manuka, was featured in AMRM way back in issue 188 (October 1994).   I got to work a fully interlocked lever frame at his home, and at exhibitions.  After a while, Tony trusted me to build a large lever frame under instruction and guidance, that being the 56 lever frame of Wagga Wagga .

The Wagga signalbox frame was built by me in the 1990s - still needing to be interlocked.

Since moving to Junee, Tony and myself have maintained a sporadic contact.  When Tony found out about my plans for the layout, he volunteered to construct Bomen’s frame as a contract build for his Mackenzie in HOLland hobby business.  I supplied Tony with as much information I had at the time  unfortunately, with the lousy small pixel signal diagram picture.  It was also a bit of a fiddle, as my rendition of Bomen’s track plan is mirror image of the original.    Tony now lives in Bendigo, and detoured into NSW via Junee to show me progress, and later the finished lever frame – fully interlocked.


Tony made 2 visits - the first one showed me the progress of the frame, prior to interlocking

On the second visit, the frame had been finished.  Here is the interlocking with the cover removed.  Note that all the tappets have numbers, which helps if the frame ever gets disassembled . Tony adds a lot of graphite for lubrication 

Now I have to learn the frame, and crunch the levers in the correct order to free up the mechanism   Excess force will break something, so you don't want to pull the levers in the incorrect order.  It will be a challenge for the future Bomen operator too, but learning the frame was part of the real signalman's job - and simulating this on a model takes things to another level of realism


Albury to Junee.  The levers have to be pulled in the pull chart order as seen on the signal box diagram.  

Albury to Platform road

Junee to Albury

Integration into the layout will be via electrical connections, rather than through a mechanical links direct off the levers

Signals will of course have to be built.



Trouble cat - gives an idea of how big the lever frame is.  She may not yet be the station cat, but takes a lot of interest in what I am doing



Observation.  A lot of older magazines contain a wealth of information.  Some of these publications get converted to a digital format, but a few never do.  It saddens me to see the wisdom of these now forgotten publications, consigned to landfill, or recycling.  Please, consider the process that brought the articles contained within to print.  The author, the editor and their desire to not only sell magazines, but the sharing of knowledge.  We are all better modellers by learning from their experience