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Fixing a traverser

Dave John


Way back I made a blog about the traverser. I’m the first to admit that traversers are not the ideal storage solution, but space dictated the use of one. At the time I used some heavy duty drawer slides, smooth movement but I always had some problems with backlash when running round a train. To add to the problem they had some sideplay, only a mm or so, but that turned out to be an issue.


Anyway, couple of weeks back I turned the layout on to run a couple of early evening trains while my tea was in the oven. Traverser unlocked, drive engaged to run it across to line 6. Turn round to check my tea, and as the traverser moves across there are a couple of very loud cracks. Yep the whole thing had shifted enough for the rail ends to catch. Result, some rather bent rails and services at Kelvinbank suspended for the day.


So I hit the internet. Proper linear ball slides used to be very expensive, but the price has dropped a lot in recent years. I ordered a pair of 600 mm slides and a ball screw, 80 quid. At that price I did wonder if I was being sold a pup, but when they arrived I was well impressed. Nice smooth linear movement, and no lateral movement that I could feel. Proper ball bearing housings for the lead screw too. Fixed a strap to the slides and clamped the thing the bench, my old dial gauge showed much less than a thou error across the whole length.


Rebuilding the traverser with the new slides proved to be less of a problem than I imagined, though of course having got it all running parallel I then had to go over all the track ends and realign them. Rail ends are now gapped to 0.5 mm.


A couple of photos, shows the general arrangement.












No engineering solution lasts forever, I will be interested to see how precise the whole thing stays over time.


I might do something more interesting with the  two run round tracks at the lh end at some point. It has occurred to me that converting them to cassettes might be a flexible use of the space.

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Looks good Dave. I'm using smaller versions of similar slides. So much better than drawer slides, it seems to me.


Interesting to see the traverser in full. Is that a hole in the wall it passes through?

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Nice solution. 

Have you figured out an equally elegant way in which to stop stock running off the end of roads that are not aligned with the exit tracks? If it can go wrong, it will go wrong. 

Best wishes 


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Cheers Mikkel, it was watching the video of your traverser that prompted me to go looking for the same sort of thing on the net. 


It is a serious hole through a serious wall ;




I could add something mechanical to cover the tracks which are not aligned with the entry and exit lines Burgundy.  However the whole railway is interlocked through the controller. No power can be applied to the rails anywhere unless the traverser and sector plate are locked in position, all the emergency stop switches are safe, all the boards are properly connected together and the crossovers are not in conflict. Once that is done the traverser knows its position so that only the two aligned tracks are fed power. 

If I am running round the train the uncouplers are up , so that pulls the magnetic ajs at the end of the train down acting as a handbrake. 


So far that has prevented accidents, but I should add a mechanical stop at some point. 

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Having a loco on the train is possibly the safer condition, as the electrical arrangements should prevent it moving. But pin point bearings are wonderful things and a careless nudge............

I have seen stock roll towards the magnet on a level siding and I had not thought of using the magnet for AJs as a handbrake.  That is quite an attractive idea. 

Best wishes 


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Hi Dave 

Not having room for pointwork for my fiddle yard I'm looking at traversers, sector plates or cassettes. They'll need to be about 1.5m long with four or five track  to accommodate a four coach plus brake van train comfortably so I'm wondering how long the traverser on your layout is. I want to be able to set up the yard for an operating session and then not have to constantly be working in the fiddle yard between trains. 

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Yep thats the size. 


In practice Pacific that equates to a loco, 20 wagons and a brake. I run 4 bogie and 2 npc passenger trains comfortably.  I could probably work with 6 bogie coaches when I get round to making them....... 

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