neilw
now that's what I call a garden railway
Posts: 284
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Post by neilw on Feb 20, 2008 17:49:06 GMT
On a typical miniature lever frame box, eg Newbury Park prior to resignalling, were/are the levers only locked against each other to prevent conflicting moves, or are the track circuits also involved? Say a shunt move was selected, I understand that all the right points would have to be selected to allow the shunt signal to be cleared, and this in turn would block any conflicting moves, but if the siding selected was already full of train, does the lever stay physically locked in the normal position, or does it move but the signal not clear? I know the signallers on here would not attempt such a dumb thing, I am trying to design some interlocking for my model!
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Tom
Administrator
Signalfel?
Posts: 4,196 
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Post by Tom on Feb 20, 2008 17:55:44 GMT
No - it was only the levers. However, you would have electric locks on levers to prevent them being moved to various positions where the mechanical locking would be released.
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Post by c5 on Feb 20, 2008 19:00:19 GMT
You would be able to move a lever from Normal to Reverse onto an occupied siding but it would not clear (local exceptions may mean it does though). It is normal to "re-stroke" a lever straight away for a through running line, it would then clear when the section ahead is clear. Also to add for the benefit of your model, that a Signal lever will "lock" a Points lever. ie The Point lever should not be allowed to move when a Signal applying to those points is reversed. I was watching a programme on Discovery Channel once where the bloke had got it the wrong way round! Hope this helps in addition to what Tom has said! ;D ;D  |
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Deleted
Deleted Member
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Post by Deleted on Feb 20, 2008 21:28:12 GMT
and remember release levers do not conflit with nothing so these are free but work he opposite to signal levers as they lock (by electric lock) in the mid position then after time delay 60 or 120sec depending on site then the lever would go the reverse position then this would unlock the electric lock on the signal lever only , nothing overides the point lock at all
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Post by railtechnician on Feb 21, 2008 4:37:28 GMT
There is a hierarchy in mechanical locking on a lever frame. Points lock points, points lock signals, signals lock points and signals lock signals in that order. This backs up JTDs point regarding locking.
As he suggests it is usually possible to throw a signal lever to route into an occupied siding but the occupied track circuits prevent the signal from clearing. In some circumstances it may not be possible to reverse such a lever due to points mechanically locking it. Other factors may come into play which may not be obvious such as potential conflicts on adjacent roads which involve 'flank' protection.
Of course the mechanical locking on the lever frame is reinforced by the electric locks as Tom mentioned, for point levers the electric locks are controlled by the point tracklocking track circuits.
Signal lever electric locks are controlled by the signal backlocking circuitry which involves proving the signal has been replaced to danger, that the trainstop is 'ON' and that the train having taken the route has cleared any points in the route.
AET helpfully mentions the release lever. You should be able to see from the mechanical locking hierarchy that if the signal lever for some reason does not replace to normal after the passage of a train the route remains mechanically locked and that in turn prevents the clearance of conflicting routes. Providing the train has been proved clear of any points in the route then a signal lever that has failed to normalise can be released after the timing relay has picked up and only then will the point levers be free to be normalised.
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neilw
now that's what I call a garden railway
Posts: 284
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Post by neilw on Feb 21, 2008 10:12:12 GMT
Thanks everyone! Next task will be autotrains, so no doubt some more questions to come.....
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Post by c5 on Feb 21, 2008 15:52:55 GMT
Thanks everyone! Next task will be autotrains, so no doubt some more questions to come..... As in through controls of a loco from a passenger car?  Aha!! ;D ;D |
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mrfs42
71E25683904T 172E6538094T
Big Hair Day
Posts: 5,922
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Post by mrfs42 on Feb 21, 2008 20:49:17 GMT
I am trying to design some interlocking for my model! Errrm. I think I drew up a locking table to answer your question on signalling the layout using Dutton's method - goodness knows where I put it though! ;D |
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Aha!! ;D ;D
