Help with catch point

Discuss the prototype and how to model it.
nberrington
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Help with catch point

Postby nberrington » Thu Apr 16, 2020 1:15 am

Please see the attached screen shot. There is a turnout proximal to this arrangement, with the left road heading into the passenger bay platform. The goods siding merge from the right (hence the catch point). This is the arrangement as it was in Swanage doing goods traffic years.

My question relates to the catch point from the siding closest the bay. Are the blades somehow hinged in the middle? It would seem both sides of the blade must move inward to protect the passenger line when the more proximal turnout is set to straight.

Not sure I’m explaining myself terribly well, but any suggestions how to practically model this gishmozel?
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nberrington
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Re: Help with catch point

Postby nberrington » Thu Apr 16, 2020 1:32 am

I found this thread. It seems to have hit a dead end. Has anyone modelled one?

https://www.rmweb.co.uk/community/index ... tch-point/

nberrington
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Re: Help with catch point

Postby nberrington » Thu Apr 16, 2020 2:24 am

I did this one on the headshunt, but it’s fairly straightforward ...
E9A96ADB-34B9-4C4B-8E8C-DEEAA931F09F.jpeg

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grovenor-2685
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Re: Help with catch point

Postby grovenor-2685 » Thu Apr 16, 2020 8:28 am

The catch points as shown the two blades would move together to open or close just like any other blades. Most such in the prototype would be old designs using hinged blades but they can equally just be sprung like more modern blades if that suits your modelling better. The Bodmin one in the link appears to have one of each!
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Keith
Grovenor Sidings

martin goodall
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Re: Help with catch point

Postby martin goodall » Thu Apr 16, 2020 8:34 am

nberrington wrote:I found this thread. It seems to have hit a dead end. Has anyone modelled one?

https://www.rmweb.co.uk/community/index ... tch-point/



Yes. I have traps built to exactly the same arrangement on my Burford layout. They protect exit to the main line from both roads of the goods yard.

I'm not sure I can immediately find a photo, but if you have a copy of MRJ No.71, you can see these traps clearly illustrated in the photos on page 138.

No promises, but I may be able to take another photo later today that shows these traps in more detail.

[It was standard GWR practice to use only single-bladed traps, despite being nagged for years by the MoT to fit double ones!)

martin goodall
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Re: Help with catch point

Postby martin goodall » Thu Apr 16, 2020 9:11 am

I was able to grab a moment to take a quick photo sooner than I had expected.

IMG_6130.JPG


I can't for the life of me remember why I put a staple into the track bed over the end of one of the timbers. Perhaps I should dig this out. A lengthened timber was originally fitted in order to mount a ground signal, which would have been detected through the trap blades, but I later decided to move this to mark the location of a nearby uncoupling magnet (so the position of this ground signal will be slightly unprototypical, but it's the sort of compromise I am prepared to make for operational convenience).

Both trap blades would have been yoked together, and would have moved with the yard point. I made my traps as dummies, and soldered them in a closed position, because you would hardly see them move in that part of the layout. However, I shall add appropriate dummy rodding in due course.

bécasse
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Re: Help with catch point

Postby bécasse » Thu Apr 16, 2020 9:26 am

I would have said that in this sort of situation, trapping fairly short sidings, single-blade trap points would have been used by all of the big-four and their predecessors, few companies would have spent more money than absolutely necessary. The traps are only there to prevent wagons running out on to the adjacent running lines having to started to move more or less of their own accord when left unbraked and thus only moving at low speed. Occasionally derailers (an LNER speciality) would be used instead of traps; scotch-blocks could undertake the same function but were difficult to integrate into an interlocked layout and therefore tended to be found only within siding complexes where a protection need existed and not at the egress point.
There would only have been a single dolly covering egress from both the converging sidings.

Armchair Modeller

Re: Help with catch point

Postby Armchair Modeller » Thu Apr 16, 2020 9:55 am

Here's one in carriage sidings at the north end of Aberdeen in BR days

9011160344_884bca1d74_c.jpg

martin goodall
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Re: Help with catch point

Postby martin goodall » Thu Apr 16, 2020 10:28 am

bécasse wrote:There would only have been a single dolly covering egress from both the converging sidings.


Yes. That is the arrangement I have planned for Burford. Just one ground disc for exit from the yard, which applies to both the converging sidings.

Incidentally, the point lever that selects which of the two sidings in the yard is connected would have been a locally operated hand lever. The point to which the traps were connected would have been the Main/Yard turnout itself (operated, and locked, from the signal box lever frame), even through the turnout within the yard was actually located between the Main/Yard turnout and the traps.

nberrington
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Re: Help with catch point

Postby nberrington » Wed Apr 29, 2020 1:24 am

I think this is it .....
(He half asks before soldering up and adding the remaining chairs)

F351BD59-66F8-452D-B8D7-28C35D4FAA0C.jpeg

David Knight
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Re: Help with catch point

Postby David Knight » Wed Apr 29, 2020 1:29 am

Unless my eyes deceive me it looks like you are going to make those catch points functional rather than cosmetic. I am impressed. :!:

Cheers,

David

nberrington
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Re: Help with catch point

Postby nberrington » Wed Apr 29, 2020 1:56 am

Going to try David. If they don’t work out I can solder them solid. I suspect they will work though ....

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CDGFife
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Re: Help with catch point

Postby CDGFife » Thu Apr 30, 2020 1:46 pm

Neil - definitely worth making them operational.

I do like it when a Cadhay operator derails their yard exit loco only to find that they had in fact ignored the ground signal and tried to exit the yard before the road had been set for them - says he who managed to do exactly that on show at Houten last year - Viewer: "Why is that loco at the bottom of the embankment?" Me: "Don't worry it's prototypical".

As an aside someone once told me Catch points catch runaways (on gradients) Trap points trap idiots (who are not paying attention - not on gradients). So I would be calling these trap points (not that my knowledge is encyclopedic mind!!) ;)

Trackwork is looking Good

Chris

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Martin Wynne
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Re: Help with catch point

Postby Martin Wynne » Fri May 01, 2020 1:46 am

CDGFife wrote:As an aside someone once told me Catch points catch runaways (on gradients) Trap points trap idiots

A catch point is the physical object designed to derail vehicles. Sometimes a single-sided catch point, sometimes a double-sided set of catch points.

These catch points are being used as traps. Other types of pointwork can also be used as traps.

Martin.
40+ years developing Templot. And counting ...

philip-griffiths
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Re: Help with catch point

Postby philip-griffiths » Fri May 01, 2020 8:58 am

This is a 1948 photo by WACamwell showing Tredegar Station. The extract of the signal diagram is From the Signal Record Society. The catch points are at the end of what were called the goods loop and the middle road. They were used for storing carriages. Behind the photographer was the level Crossing and the crossover from the storage sidings to the mainline. The latter was single passing through Tredegar station. So the crossover would have protected the mainline. I’m assuming that the catch points are protecting the crossing. However it is strange because the photography is looking downhill here. According to the diagram the catch points were worked together.

20390BDE-E431-4DC7-B75F-A6E283CF2E61.jpeg



B613E4FE-6A01-4C45-8BCE-B956CDB63DCF.jpeg

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Noel
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Re: Help with catch point

Postby Noel » Fri May 01, 2020 10:11 am

philip-griffiths wrote: I’m assuming that the catch points are protecting the crossing. However it is strange because the photography is looking downhill here. According to the diagram the catch points were worked together.


Trap [or catch] points 20 are protecting the main line from conflicting movements. Looking at the right hand side of the diagram, from the bottom the three lines shown are a single siding [part of the trap points are just visible], the single main line, and one of the accesses to the private siding [actually a large private railway] of the Tredegar Iron Company, whose main works was just to the right ["works sidings 16" on the route indicator]; the visible spur is the end of the exit trap from the works. In its heyday under the LNWR, this would have been a very busy location, which would have included all the Sirhowy valley traffic and exchange traffic from the Rhymney at Ystrad Mynach, being worked uphill to, and downhill from, the Heads of the Valleys line, plus local traffic out of the ironworks.

The main line became double just beyond the station, to the south [downhill, as you say], but remained single up to the Heads of the Valleys line at Nantybwch, apart from an intermediate crossing loop at Sirhowy. It is very likely that the photographer was standing on the level crossing and shooting under the adjacent footbridge.
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Noel

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grovenor-2685
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Re: Help with catch point

Postby grovenor-2685 » Fri May 01, 2020 10:50 am

Actually 20 in this case is not protecting the main line as 21 already does that! And anytime 21 is reversed 20 will also need to be reversed. So 20 is protecting the level crossing, the opposing sidings bottom right also have a trap that does not protect the main line either so protects the level crossing.
Both these traps could also be said to protect the opposing sidings and the right hand side one protects movements over 21 reverse but I would see both these as incidental. What is certain is that neither protect the main line, 21 does that.
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Keith
Grovenor Sidings

philip-griffiths
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Re: Help with catch point

Postby philip-griffiths » Fri May 01, 2020 1:59 pm

Thanks Keith,

Yes must be protecting the crossing, that is what my thought was. what is interesting is that they worked off a single lever.

Noel - I'm Sirhowy valley born and bred.

regards

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Noel
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Re: Help with catch point

Postby Noel » Fri May 01, 2020 2:56 pm

I understand what you are saying, Keith. It's unfortunate that we only have part of the diagram, as the identity of signal 18 would be useful; the siding is labelled on the diagram as well, but I can only access the low-res version online, which is insufficiently legible. However, R A Cooke's diagram shows cattle pens just past the box at one time, and photographs show various stock in the siding, some very close to the trap at the exit. It looks as though the siding may be a lie-by siding for goods trains [in either direction - the Goods Loop is two way] and/or for stock storage [its purpose may have changed over time with changes to the traffic], in which case it wouldn't be used as a trap siding, I assume, because of the risk of it being occupied when needed? It is also, incidentally, much longer than would be required for that purpose. If so, points 20 would be protecting the siding, and the main line as well.

philip-griffiths wrote:Yes must be protecting the crossing, that is what my thought was. what is interesting is that they worked off a single lever.


I still doubt that the traps are to protect the level crossing, as they are literally only 30-40 feet away from it, and there is no such provision on the main line, on either side. Traps in this situation normally [always?] worked off a single lever - less work for the signalman, and no chance of opening one and not the other. Perhaps you could identify signal 18 and the label on the siding for us, please? Are you on the WRRC Forum, by the way? [It is not relevant to the discussion, but the route indicator signal was a BR WR metal post lower quadrant, so post nationalisation. The LNWR used three short arms stacked vertically on one post.]
Regards
Noel

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grovenor-2685
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Re: Help with catch point

Postby grovenor-2685 » Fri May 01, 2020 3:42 pm

Well 21 protects the main line completely, so 20 is no help in that regard but it does dump onto the ground anything that moves out of the sidings and goods loop. 30 or 40 feet would be enough to stop a slow speed move in such circumstances. No-one is goint to put traps in the main line risking derailing a passenger train to save a crossing gate! I agree that it is not usually done for sidings either so there must be some special circumstances here, possibly to do with gradients.
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Keith
Grovenor Sidings

philip-griffiths
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Re: Help with catch point

Postby philip-griffiths » Fri May 01, 2020 6:38 pm

I’d prefer not to post the whole diagram as it is copyright the SRS. 18 is for moves as you point out Noel onto the Sirhowy Siding, as it is labelled on the diagram. It ran alongside the line uphill towards Sirhowy and beyond the signal box did have the cattle pens.

In none of the photos I have is the goods loop clear of carriages, so that idea of it being used for through traffic is strange. This may have been a later post 48 usage?

Unfortunately my friend, and father’s former work colleague, Gerald Davies, who knew the lines better than anyone passed away in the last 12 months otherwise I’d ask him.

Here is a Gerald photo looking north. Taken from Tasker (1986) MTA & branches, OPC.
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Noel
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Re: Help with catch point

Postby Noel » Sat May 02, 2020 11:21 am

philip-griffiths wrote:I’d prefer not to post the whole diagram as it is copyright the SRS...….Here is a Gerald photo looking north. Taken from Tasker (1986) MTA & branches, OPC.


Which is also a breach of copyright :D. I have seen the photo; I've got a copy of the book. :). There's a virtually identical shot in Tasker's Railways in the Sirhowy Valley taken by H C Casserley dated to 13/7/1958. It's so similar I think they may have been taken at the same time, but is from a viewpoint 2-3 ft to the left. There are a number of other shots of the crossing in that book, many showing the water tank where the * is on the signalling diagram.

Thanks for giving the name of the siding; I don't think it helps with the discussion, so I don't have anything else to add; I'm still not convinced by Keith's view, although it has to be respected. According to R A Cooke Section 41 the connection across the main line into the works was installed between 1880 and 1900, so the reasons for this particular formation may date back to then.

philip-griffiths wrote:In none of the photos I have is the goods loop clear of carriages, so that idea of it being used for through traffic is strange. This may have been a later post 48 usage?


The water tank, which looks to be a LNWR type with delivery hoses both sides, appears in 1920s photos, so may have been original to the late 19th century alterations, in which case an obvious rationale for its presence is for locos on up goods trains. The peak era for south Wales coal production was 1913, although inland traffic increased during WW1; after that production dropped throughout the 1920s, culminating in the start of the Depression in 1929. The Goods loop clearly stayed signalled as such, probably until closure, but I suspect that it saw progressively less use as such after WW1. The 1920s photos show stock in the sidings, but are inconclusive on whether the loop itself is clear. The GWR/LMSR agreements of 1933 would possibly have seen traffic reduced, and the takeover by the WR after nationalisation would have seen any previously northbound coal traffic diverted to easier routes.
Regards
Noel


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