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Tan-Y-Graig (GWR passing)

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Re: Tan-Y-Graig (GWR passing)

Unread postby tynewydd » Sat Jun 14, 2014 5:25 am

Chris Osment wrote:The Churston backing arm was 42 - you must be reading the small thumbnail image!

According to the SRS locking table info, it could be pulled regardless of the position of the up dock siding points 13. It did not require the ingoing disc 42 to be off if the siding points were reverse. My suspicion therefore is that you could go all the way back down the up loop if so required, as with 13 normal it locked the up loop facing points 10 normal and the Up Home, so the 'limit of shunt' presumably would have been the Down Advanced Starting 44.


Great - very handy to have the details - so I revised the plans in the folder here to accommodate much of this commentary.

I looked at doubling the line to Pwhelli, but it was not practical in modeling terms - it just cluttered up the area too much. So single passing station it still is.

I have allowed for an express to pass a stopping passenger train that was being "banked" using the normally Up line, but assumed that in that these trains would never stop at TYG (double headed) so also removed calling-on for that line. The rationale for the one-handed nature is that although stopping trains coming down the bank will have to detach a banker at TYG it will be quickly done and then they can rapidly go downhill. But on the way up they will be slow because of the bank and so having a bypass is more important.

For banking I did keep the middle road - its such a nice feature - but made the entrance and exit to it suit the arriving and departing bankers without requiring additional run-around moves. I changed the goods entrance as John suggested and fixed the gunpowder works signaling.

I now have two signal boxes, one for the station proper and one for "the bank". This led me to add extra distants but I have required that they be interlocked - I assumed "slotted" - so if the express sees the first distant is off in either direction it means that the route is clear all the way through the station and onto the bank for down express and all the way through on the up for all up trains.

I do still have a backing signal ala Churston that is used both to back a down goods train down into the yard because the entrance is near the end of the loop as well as to support any "try the bank again" activity.

Although it breaks the illusion of steepness and banking, because one line is signaled bi-directionally, we can switch out the two boxes for when we are short-handed and operate PD to Pwhelli as one single section, I hope.

I realize that all these things did not exist in one place and that there is a bit of disagreement about how common other features were - but what I want is to be broadly within the bounds of 1 inch to the foot reality and not needlessly frighten the horses.

So remaining questions -

- Did I get the distants right and are they all needed?
- I have discs 43 and 44 for goods yard and down platform backing. But Churston doesn't - was it common to have implicit permission like this on the GWR->WR ( i.e.,pass a red disc for the divergent route and have no disc for the non-divergent)?

Hopefully we are converging,
Adam
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Re: Tan-Y-Graig (GWR passing)

Unread postby John Hinson » Sat Jun 14, 2014 7:45 am

tynewydd wrote:Did I get the distants right and are they all needed?

In principle they look OK but If this is GWR the distants would have been made "fixed at caution" from a fairly early date unless there was a good reason not to. The idea behind this was that trains have to slow to 15 mph to exchange tokens anyway. It does perhaps depend on the date you are modelling.

One "good reason not to" might be a steep part of the gradient approaching the home signal and that trains needed to be kept rolling, but such occasions were pretty rare. Another might be to provide working distants that were only operated with the boxes closed. So you have some scope.

Couple to that the principle that the GWR did not normally provide a distant along a platform line where controlled by a box at each end and you may be able to simplify the distants considerably i.e. down to just the one far one in each direction.

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Re: Tan-Y-Graig (GWR passing)

Unread postby tynewydd » Sun Jun 15, 2014 10:04 am

John Hinson wrote:In principle they look OK but If this is GWR the distants would have been made "fixed at caution" from a fairly early date unless there was a good reason not to. The idea behind this was that trains have to slow to 15 mph to exchange tokens anyway. It does perhaps depend on the date you are modeling.


And I see the GWR did not have the same rapid automatic token exchange as installed as the S&D. But I do see mention of some token exchange automation on the Barnstable line - but no actual details - would that have allowed increased speeds above 15 mph? Anyone got a picture handy of that apparatus?

Ok - I removed the internal distants. I added a lever in each box as "virtual distant" that could then be used to slot the real distant in the other box. In that way the signals and points are locked in each frame and the distant only showing clear if all the homes in both boxes are pulled and the two distant levers. Is that the way it would be done?

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Re: Tan-Y-Graig (GWR passing)

Unread postby John Hinson » Sun Jun 15, 2014 10:29 am

tynewydd wrote:And I see the GWR did not have the same rapid automatic token exchange as installed as the S&D. But I do see mention of some token exchange automation on the Barnstable line - but no actual details - would that have allowed increased speeds above 15 mph?

Yes, automatic exchange apparatus is 25 mph but I have no idea what type was used on the Barnstaple line.

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Re: Tan-Y-Graig (GWR passing)

Unread postby StevieG » Sun Jun 15, 2014 9:42 pm

John Hinson wrote:
tynewydd wrote:And I see the GWR did not have the same rapid automatic token exchange as installed as the S&D. But I do see mention of some token exchange automation on the Barnstable line - but no actual details - would that have allowed increased speeds above 15 mph?

Yes, automatic exchange apparatus is 25 mph but I have no idea what type was used on the Barnstaple line.

John
Any help to also mention the nearby Minehead line? : i.e., Do I recall correctly that the GW created new non-station boxes with passing loops to increase capacity (i/c/w the setting up of Butlins' Holiday Camp at Minehead?), called Leigh Bridge and Kentsford? It seems likely these also would therefore have had token exchangers of some sort, and if so, did these permit speeds higher than 25mph?
On the other hand, I've an idea these were only opened in the 1930s, so, wrong era for 'Tan-y-Graig'?
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Re: Tan-Y-Graig (GWR passing)

Unread postby tynewydd » Mon Jun 16, 2014 1:17 am

StevieG wrote:Any help to also mention the nearby Minehead line? : i.e., Do I recall correctly that the GW created new non-station boxes with passing loops to increase capacity (i/c/w the setting up of Butlins' Holiday Camp at Minehead?), called Leigh Bridge and Kentsford? It seems likely these also would therefore have had token exchangers of some sort, and if so, did these permit speeds higher than 25mph?
On the other hand, I've an idea these were only opened in the 1930s, so, wrong era for 'Tan-y-Graig'?


Sorry guys, I se I have misled you - the period being modelled is the early 60s, the title should be Tan-Y-Graig (ex-GWR) -> so WR at this period. Therefore by then the MInehead and Barnstable branches had used some "Whitaker-type" equipment that is relevant to higher-speed exchanges and would be useful to know about for the model.
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Re: Tan-Y-Graig (GWR passing)

Unread postby davidwoodcock » Mon Jun 16, 2014 8:25 am

Surely the real point about Tan-y-Graig is not that it was WR ex-GWR, but that it was WR ex-GWR ex-CamR and that it would, therefore, have been Cambrian Railways practice that would have determined the basic shape of the 1960s signalling.

Although pilot engines were used over parts of the Cambrian main line, I can't think of a CamR location where banking locos were involved to the extent that seems to be the case at TyG, but I can think of CamR passing stations that were "modernised" (i.e. had their working costs reduced) by the GWR in the 1930s, Portmadoc, where one of the two boxes was abolished and the working concentrated at the other, being a typical example.

Interestingly the GWR didn't go out of their way to replace CamR signalling equipment, I say interestingly because the GWR did replace CamR pw with their own to an astonishing extent, "modern" CamR pw (laid with 4-hole chairs) being largely eliminated even from sidings by the mid-1930s.

Portmadoc was an interesting example pre-rationalisation because the east box up starter was slotted (by a subsequent l.c. ground frame) and yet the up distant (worked/slotted by both boxes) seems to have been capable of being cleared even if the up starter slot was on. I assume that this distant was fixed by the GWR.

Although it didn't deal with banking engines, Portmadoc was still a "busy" place because of terminating trains or portions of trains from the LNWR.
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Re: Tan-Y-Graig (GWR passing)

Unread postby John Hinson » Mon Jun 16, 2014 8:33 am

StevieG wrote:Any help to also mention the nearby Minehead line? : i.e., Do I recall correctly that the GW created new non-station boxes with passing loops to increase capacity (i/c/w the setting up of Butlins' Holiday Camp at Minehead?), called Leigh Bridge and Kentsford? It seems likely these also would therefore have had token exchangers of some sort, and if so, did these permit speeds higher than 25mph?

I wouldn't have thought so. 25 mph is the standard speed for the luxury of automatic exchangers.

(Just to be clear, the normal WR type which had to be grabbed/dropped off by drivers did not class as "automatic" so were 15 mph)

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Re: Tan-Y-Graig (GWR passing)

Unread postby Chris L » Mon Jun 16, 2014 9:13 am

davidwoodcock wrote:

I can think of CamR passing stations that were "modernised" (i.e. had their working costs reduced) by the GWR in the 1930s, Portmadoc, where one of the two boxes was abolished and the working concentrated at the other, being a typical example.


At the risk of incurring the wrath of the mods for going off topic (though it might be relevant), does anyone have a numbered signalling diagram for Portmadoc (for any period) which they'd be prepared to share, please?

Having been a regular visitor to the place for more years than I care to remember I've been looking out for one (alright, perhaps not in a very focussed way!) for some time, and since it's been mentioned......

Thanks,
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Re: Tan-Y-Graig (GWR passing)

Unread postby John Hinson » Mon Jun 16, 2014 9:47 am

Chris L wrote:At the risk of incurring the wrath of the mods for going off topic (though it might be relevant), does anyone have a numbered signalling diagram for Portmadoc (for any period) which they'd be prepared to share, please?

Having been a regular visitor to the place for more years than I care to remember I've been looking out for one (alright, perhaps not in a very focussed way!) for some time, and since it's been mentioned......

I will have a look, I may have something but I have quite a backlog of requests so it may take a while. If anybody else has something they can provide sooner all well and good.

Please don't feel afraid to start a new thread for requests like this. There is a good chance we will have to split it off eventually because diagrams often generate a lot of questions specific to them.

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Re: Tan-Y-Graig (GWR passing)

Unread postby Chris L » Mon Jun 16, 2014 9:56 am

Thanks very much John.

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Re: Tan-Y-Graig (GWR passing)

Unread postby tynewydd » Mon Jun 16, 2014 9:02 pm

davidwoodcock wrote:Surely the real point about Tan-y-Graig is not that it was WR ex-GWR, but that it was WR ex-GWR ex-CamR and that it would, therefore, have been Cambrian Railways practice that would have determined the basic shape of the 1960s signalling.

Although pilot engines were used over parts of the Cambrian main line, I can't think of a CamR location where banking locos were involved to the extent that seems to be the case at TyG, but I can think of CamR passing stations that were "modernised" (i.e. had their working costs reduced) by the GWR in the 1930s, Portmadoc, where one of the two boxes was abolished and the working concentrated at the other, being a typical example.


So you are suggesting that a possible improvement made by the GWR would have been to consolidate the two boxes, David? And because of the level crossing it would be obvious which box site would be still used... I assume that would also have required power signalling for the longer pulls? And your comment about retaining the CamR signals is because it is likely that the equipment would be nearly identical, only the boxes would have been changed? I think the 1930s would have fitted.

The limited research I can find on GW research into automated token exchange on the two branches in somerset suggested that they found the ex-SD&JR Whittaker equipment not suitable/reliable and they sent to Scotland for details of the Manson exchangers. For those I see reference to the on-board equipment being inside the guards compartment (it comes out through the door) and the guard had a bellcode to use to the loco to signal that the token exchange had occurred ok. Thus not much to see on the rolling stock/locos. On this site there is a picture of part of the trackside equipment for Manson, but not the whole thing. What I am suggesting is that this line might have justified Manson being pursued at a time the boxes would have been consolidated.

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Re: Tan-Y-Graig (GWR passing)

Unread postby davidwoodcock » Mon Jun 16, 2014 9:17 pm

The "basic" Portmadoc was very similar - passing loop on single line, two platforms, two boxes, one level crossing, but lots of sidings and, unsurprisingly, no centre road for bankers. When the GWR rationalised it (to reduce staffing costs) in the 1930s the box at the east end (where the level crossing was) was retained and extended to take a longer frame and the box at the west end abolished; the points at the west end would have become power worked, almost certainly by electric motors powered by a hand generator set in the east box.

The most typical Cambrian signals were probably Tyers (on wooden posts, of course) and some of those were still around almost to the end of mechanical signalling. Others would have had GWR/WR/LMR tubular post replacements. Look at pictures of almost any location along the Cambrian coast back in steam days and you will see what I mean. I am sure that TyG at least would have been much the same even though it had provision for banking.
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Re: Tan-Y-Graig (GWR passing)

Unread postby Chris Osment » Tue Jun 17, 2014 11:59 am

I would need to dig out the relevant notes from somewhere (but need to go back into the sunshine to finish painting my garden shed!), but IIRC the GWR did eventually use a modified form of Whitaker for the Minehead and Barnstaple Branches.

Also, surely, the max speed for the auto exchanges was 40MPH? Coincidental with their introduction of the auto exchangers the GWR converted the 'fixed' distants back to working again.
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Re: Tan-Y-Graig (GWR passing)

Unread postby MRFS » Tue Jun 17, 2014 3:05 pm

I've started a new thread for Portmadoc..
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