Switching three connected points

[Stubby47]

A question for the pointwork experts please.

 

Would these 3 points all be switched 'together' ?

 

[5BarVT]

No.

[5BarVT]

Now to be a bit more helpful: you can operate all three together but you end up with only line straight and one line curved for each of the settings.  That means you can’t have both lines straight at the same time for legitimate parallel moves.

It needs to be done as one crossover and one single end.

Paul.

[Stubby47]

On 22/07/2022 at 20:59, 5BarVT said:

Now to be a bit more helpful: you can operate all three together but you end up with only line straight and one line curved for each of the settings.  That means you can’t have both lines straight at the same time for legitimate parallel moves.

It needs to be done as one crossover and one single end.

Paul.

 

Agreed.  I tried playing with some possible shunting moves and realised that moving all three at once was not helpful.  The lower of the three will be the separate point.

[Michael Hodgson]

Probably not applicable to your layout, but if as sometimes was found the middle road is a freight only carriage siding avoiding line etc, that point would probably be a "wide to gauge", ie arranged as a trap so unauthorised movements from the middle road don't foul either of the through running lines, but instead drop into the dirt in between them. 

 

This looks at first sight like an ordinary point, but lacking its tie bar so its blades don't move together, and you won't find one in the Peco range.  The way it would work is that there would be two crossovers, but only one blade on the middle point moves when you reverse the crossover, the other being already set.  The two crossovers would obviously be interlocked so they can't both be set curved at the same time.  With the two crossovers set for straight running, neither blade is set, so the track becomes wide to gauge and any runaway drops into the four-foot, hopefully staying upright and clear of the adjacent lines.

[Stubby47]

15 minutes ago, Michael Hodgson said:

Probably not applicable to your layout, but if as sometimes was found the middle road is a freight only carriage siding avoiding line etc, that point would probably be a "wide to gauge", ie arranged as a trap so unauthorised movements from the middle road don't foul either of the through running lines, but instead drop into the dirt in between them. 

 

This looks at first sight like an ordinary point, but lacking its tie bar so its blades don't move together, and you won't find one in the Peco range.  The way it would work is that there would be two crossovers, but only one blade on the middle point moves when you reverse the crossover, the other being already set.  The two crossovers would obviously be interlocked so they can't both be set curved at the same time.  With the two crossovers set for straight running, neither blade is set, so the track becomes wide to gauge and any runaway drops into the four-foot, hopefully staying upright and clear of the adjacent lines.

 

Very helpful & informative - thanks.

[iands]

Here's a part of a diagram (York 1951 resignalling) that shows what @Michael Hodgson described. The points 467 and 472 adjacent to 94 GPL are single blade switches, effectively forming a set of 'trap points' when normal, and are associated with the other sets of points, 467 and 472 respectively, which are 'standard' two-blade points (connected with stretcher bars etc.) 94 GPL is on the Middle Road (between the then old Platform 14 and 15) that served as an engine run round/siding.

[The Stationmaster]

And here's a photo of a real one - albeit in Sydney NSW so the operating mechanism is to NSWGR standards but the principal is exactly the same.   Alas I was too late to get a photo of the ones at Perth (Scotland) which would have probably had a mechanism similarly arrange to the one at York where the two switches were worked separately.  There also used to be mechanically worked examples in Britain worked off a single lever but in the sort of situation seen in my Sydney picture it was more sensible to work each switch rail separately forming one end of a crossover with the point it led to. ( which is how the Sydney example is arranged but with power operation of course).

 

Lovely things - once adjusted - and I was greatly disappointed that it was found possible to avoid using one for the layout alterations which I required to be made at Didcot in the early 1990s.

 

Edited July 24, 2022 by The Stationmaster

[TheSignalEngineer]

If the trap is between two running lines as it appears to be then it needs to be a wide-to-gauge configuration as in SM's picture for both running lines to be used simultaneously. 

The arrangement can be worked by two or four levers. Standing looking at the toe of the trap the left switch will work with the top connection and the right switch with the lower one in a 2 lever arrangement. 

[Stubby47]

The trap, in my case is not between two running lines, as the lower line is just a siding.

 

However, thanks all for the spread of information,  as usual there is a wealth of knowledge on the forum and a generous spirit to share.

[TheSignalEngineer]

32 minutes ago, Stubby47 said:

The trap, in my case is not between two running lines, as the lower line is just a siding.

 

In that case the trap and top point end could be double ended. 

Is the middle line also a siding? Depending on line use  and other considerations the the lower point could either be a hand lever or box worked.

[TheSignalEngineer]

Is there a full layout plan somewhere?

[Stubby47]

Full track plan is also in my Newham link, below.

 

A terminus, with entrance from the left.

 

 

 

 

 

[5BarVT]

Ah!

Not the plan but the name.  If you are modelling Newham as the Goods Branch that it was, the trap point question becomes easy.  It’s off the layout to the left by quite a long way and up quite a lot too at Penwhithers Jn,

Paul.

[Stubby47]

11 hours ago, 5BarVT said:

 It’s off the layout to the left by quite a long way and up quite a lot too at Penwhithers Jn

 

If I had the time/space/money I'd model the whole of the Chacewater to Newquay line.

I would probably add the Newham branch too.

[DavidBird]

On 24/07/2022 at 18:29, Stubby47 said:

Full track plan is also in my Newham link, below.

 

A terminus, with entrance from the left.

 

 

 

 

 

We have a very similar layout at Boat of Garten on the Strathspey Railway, (except without the upper siding and associated crossover and the rhs crossover is trailing rather than facing).

There the points from the Up Loop ( R to L in your diagram) to the yard are worked as a pair (ie. bottom and middle) whilst the main line (upper) points are a single.

[TheSignalEngineer]

Very much a flavour of the Leek & Manifold's Hulme End station.  On that the station was at the right hand end of your incoming track. Push back to run round. There was only one signal post to the left hand end which had Home and Starting arms on it, There was a 5-lever frame which controlled the three points in the running line and associated traps and the two signals.

You could always add a bit of standard gauge track at the end of one or more of the sidings and build a couple of transporter wagons. A picture of one from elsewhere on the site which seems to have escaped the crash.

 

Edited July 26, 2022 by TheSignalEngineer

[St Enodoc]

9 minutes ago, TheSignalEngineer said:

Very much a flavour of the Leek & Manifold's Hulme End station.  On that the station was at the right hand end of your incoming track. Push back to run round. There was on;y one signal post to the left hand end which had Home and Starting arms on it, There was a 5-lever frame which controlled the three points in the running line and associated traps and the two signals.

You could always add a bit of standard gauge track at the end of one or more of the sidings and build a couple of transporter wagons. A picture of one from elsewhere on the site which seems to have escaped the crash.

 

A broad-gauge transporter wagon would be fun.

[jim.snowdon]

On 24/07/2022 at 11:10, Michael Hodgson said:

Probably not applicable to your layout, but if as sometimes was found the middle road is a freight only carriage siding avoiding line etc, that point would probably be a "wide to gauge", ie arranged as a trap so unauthorised movements from the middle road don't foul either of the through running lines, but instead drop into the dirt in between them. 

 

This looks at first sight like an ordinary point, but lacking its tie bar so its blades don't move together, and you won't find one in the Peco range.  The way it would work is that there would be two crossovers, but only one blade on the middle point moves when you reverse the crossover, the other being already set.  The two crossovers would obviously be interlocked so they can't both be set curved at the same time.  With the two crossovers set for straight running, neither blade is set, so the track becomes wide to gauge and any runaway drops into the four-foot, hopefully staying upright and clear of the adjacent lines.

This arrangement certainly was (and probably still is) very common on the London Underground for centre reversing sidings.

[melmerby]

East Grinstead 2007:

https://www.derekhayward.co.uk/OxtedtoEastGrinstead/East-Grinstead-Network-Rail/i-cDrQNRn/A

Edited July 26, 2022 by melmerby