15.01.19
Repoint: revolutionising track switch
Source: RTM Dec/Jan 2019
Sam Bemment, senior R&D engineer at Loughborough University, brings us an update on the Repoint project – a scheme which has transformed the track switch as we know it.
In the August/September issue of RTM, I presented the history of and reasons behind the Repoint project at Loughborough University. Repoint set out to reengineer track switches to feature fault tolerance, primarily through the use of redundancy, to significantly boost reliability and availability whilst minimising inspection and maintenance requirements. Since I wrote the first article, we have come a long way, but not without some trials and tribulations.
By mid-October, all subassemblies were together and tested in our laboratories at Loughborough University. Whilst it was possible to test all the components individually in the lab, the real loadings come from the weight and flexure of the switch rails. The switch rails also link the three redundant actuators, meaning that a full test was very difficult in the lab. For this reason, we had planned an extra period of testing with the whole unit assembled. The risk of undergraduate amputations was too high to assemble this in a campus car park, so we shipped our bearers to Progress Rail’s Sandiacre HQ.
Repoint POE functions around off-the-shelf track components, so Progress Rail provided us with a whole assembled panel and we simply removed a few components to be replaced by our custom items. The Progress Rail staff kindly did all the heavy lifting to get our actuator bearers in place and clipped up. Having stared at many design iterations in false-colour CAD for years, it was a surreal moment to see it fully assembled. And then we got to switch the power on.
In the lab, everything is ‘perfect.’ In the real world, less so. Every R&D engineer knows this, but it’s the extent and type of difference that can catch you out. In this case, it transpired that the BR standard signalling supply in the cabinet provided a roller-coaster output which promptly, and frustratingly, decided to fry half the embedded sensors leading to quite a lot of smoke, a few grey hairs, and some last-minute soldering.
A similar small problem related to the lifting geometry at the final distance block, which was solved with the aid of a milling table – at which point we found all other adjustments could be taken up by our set-up shims designed in from the start, which was a relief! However, by mid-November, we had ironed out the minor mechanical and electrical issues that hit first-of-type – the sort of stuff you only seem to find out when it’s cold and raining.
Repoint has a ‘dial’ to allow the installer to specify custom swing time and power use at each location. Turn it up to 11 and the switch will throw much faster than the old pneumatic machines. We nervously turned it down to the lowest setting. Then we commanded the points over, and over they went. It worked. Simple as that. A video of these first throws, shared by my colleagues Tim Harrison and Sharon Henson on social media, has received over 50,000 views. Not bad for a track switch in a car park.
We were then ready to stick it in the ballast and Great Central Railway (GCR) provided the test site at Quorn Station. Of course, nothing ever goes smoothly, and despite best preparations, a crane breakdown on installation day put us back a few weeks against schedule.
However, as I write this article, Repoint is installed and has passed its first round of functional testing in track. The GCR P-way crew are busy installing the crossover and closure panels and, shortly, a lowly consolidation train will be the first vehicle to cross ‘the future of track switching’ – quietly, probably late evening, and without very much fanfare.
We have a period of testing to go through until early 2019 where interested parties are welcome to come and see the installation, as well as a launch event in January.
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