Another Geoff Posted July 10, 2021 Share Posted July 10, 2021 Having studied several photographs of LNER Ground/Shunt Signals, am I correct in assuming that the disc does not pivot about it's centre, but instead considerably to the left of centre when facing the disc? Or is it a geared mechanism from the rear crank axle? Link to post Share on other sites More sharing options...
micknich2003 Posted July 10, 2021 Share Posted July 10, 2021 Geoff, here are a few pictures I have taken over the years. You can see the disc is pivoted off centre, it is actually bolted to a casting, the spindle passes through the casting only. Almost fifty years ago, there was a brilliant article in Model Railway News on scratch building these signals. If I can help further, please ask. Best Wishes, Mick. 8 2 1 Link to post Share on other sites More sharing options...
Another Geoff Posted July 10, 2021 Author Share Posted July 10, 2021 Superb Mick, thanks for the photos, including the first I've seen from dead straight on! I'm certainly interested in any scratch building info, or even the article if you have it and are able and willing to share it. Link to post Share on other sites More sharing options...
micknich2003 Posted July 10, 2021 Share Posted July 10, 2021 5 minutes ago, Another Geoff said: Superb Mick, thanks for the photos, including the first I've seen from dead straight on! I'm certainly interested in any scratch building info, or even the article if you have it and are able and willing to share it. Geoff, I need to find it and probably rescan it. Link to post Share on other sites More sharing options...
Another Geoff Posted July 10, 2021 Author Share Posted July 10, 2021 Oooh, that would be luverly. Please don't put yourself out though, I'm certainly in no rush, we haven't moved to the new house with the loft begging for a layout yet! Thank you so much for your help. Link to post Share on other sites More sharing options...
Michael Hodgson Posted July 10, 2021 Share Posted July 10, 2021 You don't want mechanical signals to be evenly balanced - in order to fail safe they should be biased to return to their most restrictive indication if the wire breaks. Note the casting is much thicker on one side of the pivot than the other. The counterweight is what does most of that job though. 1 Link to post Share on other sites More sharing options...
LNERGE Posted July 11, 2021 Share Posted July 11, 2021 (edited) Some more detail in this album. Click on the image and it should take you to several photos. Edited July 11, 2021 by LNERGE 3 Link to post Share on other sites More sharing options...
Another Geoff Posted July 12, 2021 Author Share Posted July 12, 2021 On 10/07/2021 at 21:17, Michael Hodgson said: You don't want mechanical signals to be evenly balanced - in order to fail safe they should be biased to return to their most restrictive indication if the wire breaks. Note the casting is much thicker on one side of the pivot than the other. The counterweight is what does most of that job though. Good point; built in redundancy. Should the counterweight mechanism become detached somehow from the disc axle, the disc bias will still do the job! Link to post Share on other sites More sharing options...
Another Geoff Posted July 12, 2021 Author Share Posted July 12, 2021 15 hours ago, LNERGE said: Some more detail in this album. Click on the image and it should take you to several photos. Oooh, fantastic! Thank you! Link to post Share on other sites More sharing options...
Michael Hodgson Posted July 12, 2021 Share Posted July 12, 2021 2 minutes ago, Another Geoff said: Good point; built in redundancy. Should the counterweight mechanism become detached somehow from the disc axle, the disc bias will still do the job! Indeed but that scenario is fairly unlikely - I recognise those signals and their owner likely as not found the big weight rusted solid to its arm until he had cleaned it all up! When the lever is put back to normal the tension on the wire relaxes, and the counterweight pulls the wire back to its starting position against any resistance from unlubricated pulleys, overgrown undergrowth etc. The position of the counterweight can be adjusted (moving it further from the pivot gives more leverage) between those two bolts through the arm which are to limit how far it could slide along the arm if it were not properly secured to it. Link to post Share on other sites More sharing options...
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