Signalling Polsarrett S&T

[garethashenden]

Many thanks for the kind words. Not that I am trying to tempt you down the road of fully working point rodding ... but for those who might be tempted, here is a video of the rodding working:-

Best Wishes,
Howard

Are the points driven by the rodding or is the rodding driven by the points?

 

[J_F_S]

Actually both. Two of the crossovers are just worked via the rodding as are all od the Facing Point Locks. The two crossovers which include the ends of the double slip are driven via the rodding and via an underbaseboard mechanical drive as I was concerned that the double slips might over oad the job.
Of course, working via the rodding means it has to be correctly designed so - for example - the runs include expansion compensators. Here is a photo of the underboard mechanical drives - they cause a vertical spindle to turn which passes up through the basboard and a scale bellcrank is attached to the other end. The bellcrank is the final one in the scale rodding and the drive is then take above the baseboard to the stretcher.



Conscious that I have big-time hi-jacked the thread so if more is needed, I can start a new one.

Best Wishes,
Howard

 

[Pencarrow]

Hi Chris. Firstly your layout looks absolutely brilliant and I can see that two Chris's have the same thoughts about small layouts! To be honest your proposed signalling would be considered as a bit 'over the top' for a small country station (especially an NCR one) where economy in operation was key. However, Rule 1 applies and it can be assumed that the traffic justified a fully signalled layout. Give me a few days and I will come back to you on your proposal. I can work out the point rodding and signal wire runs for you as well. Don't also forget about a telegraph pole route and wires that always seem to be missing from models. However, I can tell you a tale about one of my layouts and a certain household cat, but thats for later.

The two signals you have can be fitted in, and they look very professional in construction.

Interesting that you posted a photo of 14B and 14C points at Bodmin General as I'm somewhat involved at present in implementing a signalling scheme there for a new second platform.....

Morning all

So what are the collectives' thoughts on a groundframe for the platform crossover as opposed to being controlled directly from the cabin? I assume that the ground frame would be released by a lever in the signal cabin?

Would the frame be located on the platform or clay dries side?

Thoughts welcomed.

 

[Pencarrow]

Actually both. Two of the crossovers are just worked via the rodding as are all od the Facing Point Locks. The two crossovers which include the ends of the double slip are driven via the rodding and via an underbaseboard mechanical drive as I was concerned that the double slips might over oad the job.
Of course, working via the rodding means it has to be correctly designed so - for example - the runs include expansion compensators. Here is a photo of the underboard mechanical drives - they cause a vertical spindle to turn which passes up through the basboard and a scale bellcrank is attached to the other end. The bellcrank is the final one in the scale rodding and the drive is then take above the baseboard to the stretcher.

View attachment 154045

Conscious that I have big-time hi-jacked the thread so if more is needed, I can start a new one.

Best Wishes,
Howard

Hi Howard,

Fascinating work there. I definitely think that it deserves a thread of its own. Can't be many layouts that have functional rodding to this degree.

 

[cbrailways]

Chris. On the signalling layout I'm preparing for you the crossover (4 and 5 points on your signalling sketch) will be GF controlled, mechanically released from the SB. The platform end will have a Facing Point Lock. The GF will be sited opposite the loop end of the crossover and will have 3 levers.

Meant to ask before about the level crossing. Are you intending for it to cross a public road and therefore needing interlocked gates?

 

[Pencarrow]

Chris. On the signalling layout I'm preparing for you the crossover (4 and 5 points on your signalling sketch) will be GF controlled, mechanically released from the SB. The platform end will have a Facing Point Lock. The GF will be sited opposite the loop end of the crossover and will have 3 levers.

Meant to ask before about the level crossing. Are you intending for it to cross a public road and therefore needing interlocked gates?

Cheers, your help and guidance is much appreciated. Yes, like Nanstallon, the road crossing will be a public road with LC gates.

Looking forward to seeing your cunning plan and incorporating it into the layout.

 

[Pencarrow]

Chris. On the signalling layout I'm preparing for you the crossover (4 and 5 points on your signalling sketch) will be GF controlled, mechanically released from the SB. The platform end will have a Facing Point Lock. The GF will be sited opposite the loop end of the crossover and will have 3 levers.

Meant to ask before about the level crossing. Are you intending for it to cross a public road and therefore needing interlocked gates?

@cbrailways Is the washer (center of shot) where you were thinking of the ground frame?

 

[cbrailways]

Hi Chris. Yes, the ideal place for the GF. In addition it might be worth considering it to work the platform line to siding connection as well but with entry and exit shunt signals as with a train stood on the loop the view from the GF would be obstructed preventing the use of handsignals. In that case the GF would have 6 levers.

 

[Pencarrow]

Hi Chris. Yes, the ideal place for the GF.

Smashing, thanks for that.

 

[Pencarrow]

Borrowed from a thread over on RMweb, a couple of reference docs with loads of S&T miscellany in:

https://dickthesignals.co.uk/onewebmedia/C1-C355 training pamphlets.pdf

https://dickthesignals.co.uk/onewebmedia/22 mechanical interlocking.pdf

Looking at the lever frame diagrams answers a question I've had for a while. When the rods exit a signal box do they push or pull to change a turnout from normal?

The answer seems to be dependent on the frame and how the final crank is set up in the box. Some seem to push, others pull.

 

[Pencarrow]

In other S&T news, the signals are in...











And attention is turning to the level crossing gates, a kit from MSE:

 

[Phil O]

Borrowed from a thread over on RMweb, a couple of reference docs with loads of S&T miscellany in:

https://dickthesignals.co.uk/onewebmedia/C1-C355 training pamphlets.pdf

https://dickthesignals.co.uk/onewebmedia/22 mechanical interlocking.pdf

Looking at the lever frame diagrams answers a question I've had for a while. When the rods exit a signal box do they push or pull to change a turnout from normal?

The answer seems to be dependent on the frame and how the final crank is set up in the box. Some seem to push, others pull.

The only hard and fast rule seems to be there should be as much pull as there is push in the run other than that, when the lever is in the normal position in the frame the turnout will usually be set for the main road through the turnout.

 

[Nick C]

I believe it's more common to have the lever push the first bit of rod when reversed, but as others have said, both are possible. You need to have equal amounts of push and pull to account for expansion (we've got one at the MHR that can be a real pig when it's hot, because half the run is in the shade, which disrupts the expansion). As it's LSWR, FPLs normally out (so the lever will be reversed to lock the points). I'd expect 'normal' route to be the main route through the platform.

The points leading to the dries would be hand operated. IMHO it's a short enough layout that all the points would be worked from the box, not needing an extra ground frame (max 180 yards in the early days, 350yds later), and there might be a common FPL lever for both the right-hand loop points and the goods yard ones, so I'd expect three black levers and two blue ones, plus signals and gate release.

 

[Pencarrow]

I believe it's more common to have the lever push the first bit of rod when reversed, but as others have said, both are possible. You need to have equal amounts of push and pull to account for expansion (we've got one at the MHR that can be a real pig when it's hot, because half the run is in the shade, which disrupts the expansion). As it's LSWR, FPLs normally out (so the lever will be reversed to lock the points). I'd expect 'normal' route to be the main route through the platform.

The points leading to the dries would be hand operated. IMHO it's a short enough layout that all the points would be worked from the box, not needing an extra ground frame (max 180 yards in the early days, 350yds later), and there might be a common FPL lever for both the right-hand loop points and the goods yard ones, so I'd expect three black levers and two blue ones, plus signals and gate release.

Hi Nick,

This signalling lark is a minefield!

I've worked on the first bit of rod being push, so that's good. Have also taken account of equal amounts of pull and push, including use of compensators.

I've go the two sets of points into the dries as being hand pulls, just need to remember the safe place I put them.

Interesting thought on the two FPLs being off the same lever. So, if I understand correctly, the FPLs would be unlocked (tiebar free to move) when the lever was normal and locked when pulled by the signal bloke?

Also interesting thoughts on the ground frame. I originally didn't even consider one but the idea was out forward by multiple folk on here and RMweb. I quite like the idea of one though for the far crossover.

Mind you, how much of all this wishful thinking I get done before the show on the 24th is a moot point.

Please carry on discussing folks.

 

[Nick C]

Hi Nick,

This signalling lark is a minefield!

I've worked on the first bit of rod being push, so that's good. Have also taken account of equal amounts of pull and push, including use of compensators.

I've go the two sets of points into the dries as being hand pulls, just need to remember the safe place I put them.

Interesting thought on the two FPLs being off the same lever. So, if I understand correctly, the FPLs would be unlocked (tiebar free to move) when the lever was normal and locked when pulled by the signal bloke?

Also interesting thoughts on the ground frame. I originally didn't even consider one but the idea was out forward by multiple folk on here and RMweb. I quite like the idea of one though for the far crossover.

Mind you, how much of all this wishful thinking I get done before the show on the 24th is a moot point.

Please carry on discussing folks.

It is indeed - best practice is to look at real examples - the SRS site is good for that (Southern Railway Signal Box Diagrams) - see Gunnislake as an example (Gunnislake Signal Box - but direct links often don't work)

Yes, the points are free to move then the lever is normal, locked when it's pulled. There would also be a fouling bar in advance of (before) the points, basically a 60ft long bar sitting in the flangeway, that lifts up as the lever is moved, preventing the signalman from replacing the lever as a train is approaching the points from the facing direction. I think that's why points very close together often had a common FPL lever - as there wouldn't be room for a second fouling bar between the points - I might be wrong on that though! In later years, track circuits were used instead, with electrical locks to stop the signalman releasing the FPL when there was a train in the way.