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Possy92

Mechanical Doubleslips

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Hi all,

 

I'm currently planning a layout at the end of a branchline, and as such, am looking forward to the peco doubleslip bullhead points they're hopefully bringing out later this year

 

A quick questions if I may. as it will be mechanical signalling (with rodding and mechanical box) are there any examples of doubleslips being controlled by a mechanical box? Have seen a picture of ones controlled via a groundframe, but I'm stuggling to find pictures of such an example.

 

kind regards

 

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I assume that Embsay as shown below (image courtesy of the David Hey Collection) would have double slips controlled from the signal box as they are connected directly to the mainline and would need to be operated to provide access to the goods yard and to protect the mainline from errant vehicles straying.

0-0-a-Embsay-Diagram-RD-Pulleyn.jpg

Edited by Aire Head
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Allscott signal box between Shrewsbury and Wellington (Salop) has a double slip, and on a 70MPH main line as well. It was operated by rodding. See picture below on my Flickr site of said location after the box had shut. 

 

DBR5-132

 

Paul J.

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8 hours ago, Aire Head said:

I assume that Embsay as shown below (image courtesy of the David Hey Collection) would have double slips controlled from the signal box as they are connected directly to the mainline and would need to be operated to provide access to the goods yard and to protect the mainline from errant vehicles straying.

0-0-a-Embsay-Diagram-RD-Pulleyn.jpg

 

If I am interpreting that diagram correctly only one end of the double slips has a level number and is controlled by the box - in both cases paired up on the same lever and rodding with the point at the other end of the crossover they are part of. Presumably therefore the other end is operated by a lever on the ground.

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35 minutes ago, Phil Bullock said:

 

If I am interpreting that diagram correctly only one end of the double slips has a level number and is controlled by the box - in both cases paired up on the same lever and rodding with the point at the other end of the crossover they are part of. Presumably therefore the other end is operated by a lever on the ground.

 

That makes sense.

 

Especiallywhen factoring in the story of a goods train collecting from the yard was shunted out of the way for a passing train. The double slips into the headshunt hadn't been used for years and were in poor condition.

 

The loco crew wanting to get shunted as quick as possible and not being prepared to wait for the mainline to become free again drove over the slip which promptly disintegrated underneath them.

 

In order for them to consider this course of action at least part of the slip would need to be controlled by a ground frame.

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17 minutes ago, Titanius Anglesmith said:

Not far from Embsay, Grassington had a set of double slips, both ends of which were on the running line and worked from the ‘box. 

And here's the diagram :)

 

grassington.jpg

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Pic of Grassington with signalbox in 1952 on this page:

http://www.disused-stations.org.uk/g/grassington_threshfield/index.shtml

 

And 1961:

http://www.disused-stations.org.uk/g/grassington_threshfield/index2.shtml

 

(Edit: thought box had gone, but is still there I think, just out of shot to left of slip)

Edited by keefer
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Most of the stations on the Wharfedale line appear to have had double slips connected to the mainline, Addingham and Bolton Abbey also spring to mind. 

 

I'm certainly aware that double slips connected to the mainline is not uncommon on former midland routes.

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I'm not sure why this question arose.  Before power operation came in double slips would inevitably have been mechanically worked and there were loads of them all over the country.  They were of course not commonly found in running lines except at large stations and also at termini because of the restrictions on the use of facing points but some examples did exist in lines used by fast through trains, e.g Patney & Chirton (on the GWR) where there was one in the Up Main Line.  And they could be found on secondary/branch lines where, no doubt, space considerations resulted in their adoption.

 

A more interesting question might be to what extent separate stretcher bars were used for the two point toes at the same end of a double slip ;0

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22 minutes ago, The Stationmaster said:

A more interesting question might be to what extent separate stretcher bars were used for the two point toes at the same end of a double slip ;0

 

That sounds like a leading question Mr SM....... are you alluding to the use of a single stretcher bar across both sets of blades?

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Thanks all for your wonderful pics and replies! Will be taking some inspiration from the track plans too!

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2 hours ago, Phil Bullock said:

 

That sounds like a leading question Mr SM....... are you alluding to the use of a single stretcher bar across both sets of blades?

I wouldn't fancy having to keep that in adjustment !

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Try looking at Ventnor on the Isle of Wight, and the down main at Nantgarw, Cardiff Railway.

 

Ian.

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14 hours ago, Aire Head said:

Most of the stations on the Wharfedale line appear to have had double slips connected to the mainline, Addingham and Bolton Abbey also spring to mind. 

 

I'm certainly aware that double slips connected to the mainline is not uncommon on former midland routes.

 

It's my impression that double slips on running lines, except at termini, were very rare since they would inevitably include a facing connection. The classic arrangement is illustrated by @Aire Head's diagram of Embsay, where two parallel goods yard lines join, with a trailing connection to the running line (via a single slip to the down line in the Embsay example, also providing a trailing crossover between the running lines) and a trap siding. Only those switches forming part of the crossover from yard to running line are worked from the signalbox; the other end of the slip is worked by hand lever(s). From the point of view of protecting the running line, it doesn't matter which of the two goods yard lines the slip is set for. From the point of view of shunting the yard, it may have been more convenient to have this end of the slip worked by hand rather than continually distracting the signalman's attention from more important matters, i.e. what was happening on the running lines.

 

At Embsay, the down sidings have functionally the same arrangement but built entirely from plain turnouts - I thought this might be because they were a much late addition but I see they are there on the 1889 OS 25" map, the station having only opened the year before.

Edited by Compound2632
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In 1966 I worked on putting in several double slips for the new Curzon Street Parcels depot. They were all worked from the new mechanical signal box. All had separate stretchers and two adjusting cranks for each end.

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11 hours ago, Compound2632 said:

 

It's my impression that double slips on running lines, except at termini, were very rare since they would inevitably include a facing connection. The classic arrangement is illustrated by @Aire Head's diagram of Embsay, where two parallel goods yard lines join, with a trailing connection to the running line (via a single slip to the down line in the Embsay example, also providing a trailing crossover between the running lines) and a trap siding. Only those switches forming part of the crossover from yard to running line are worked from the signalbox; the other end of the slip is worked by hand lever(s). From the point of view of protecting the running line, it doesn't matter which of the two goods yard lines the slip is set for. From the point of view of shunting the yard, it may have been more convenient to have this end of the slip worked by hand rather than continually distracting the signalman's attention from more important matters, i.e. what was happening on the running lines.

 

At Embsay, the down sidings have functionally the same arrangement but built entirely from plain turnouts - I thought this might be because they were a much late addition but I see they are there on the 1889 OS 25" map, the station having only opened the year before.

 

By connected to the mainline I meant accessed from and not part of the mainline! :blush:

 

Certainly the Midland in West Yorkshire favoured using single slips to create a trailing connection into the goods yard and simultaneously create a trailing cross over between the running lines.

 

The down sidings at Embsay are the exchange sidings for the quarry which may explain why they are done using plain turnouts?

 

 

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19 hours ago, Wickham Green said:

I wouldn't fancy having to keep that in adjustment !

I suspect Mr SM was really alluding to the number of levers rather than just the number of stretchers, its the number of levers that interests the operators and signallers whereas the detail design of the stretchers is only of interest to the poor signal techs who have to set up and maintain them.

In relation to levers the usual arrangement is to have one lever for each end of a double slip, either or both of which may form part of a crossover. Logically this arrangement allows provision of all required locking, after all a double slip is the logical equivalent of two turnouts toe to toe.

Certain railways, notably the GWR and the LNWR, did sometimes provide two seperate levers for one end of a double slip, apparently to allow provision of different locking. I have yet to see any logic in the practice which eventually died out so there could not have been any real need.

Rgds

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22 hours ago, Phil Bullock said:

 

That sounds like a leading question Mr SM....... are you alluding to the use of a single stretcher bar across both sets of blades?

Not really a leading question Mr Bullock sir although 'Signal Engineer has very properly picked up the most important baton.  Model railway r-t-p double slips appear to invariably come with a single stretcher bar working both sets of switches at each end.  In thereal world, as SE has explained that creates problems of adjustment and for maintenance.  

 

As Grovenor pointed out there is another area where it can also be awkward and that is where it can involve interlocking problems (= operational problems) if all 4 switches are worked off a single lever.  Start from single slip where in the real world it was not at all common for both ends to be worked by the same lever - usually because the two ends formed parts of separate crossovers.   Now convert that to a double slip and again you will normally find the two ends are worked by different levers for, often, a similar reason.  The Embsay diagram already posted illustrates the principle involved as does the Grassington one,  In both cases the slip ends are working as parts of different crossovers from each other while at Embsay,  in the case of both double slips, one end is signal box work and the other end is worked by hand lever(s).

 

The use of separate stretcher bars also allows the switches at an end to be worked by two separate levers  - something the GWR definitely did and indeed something that could be found in some GWR power worked double slips (e.g. at Bristol Temple Meads West, levers 234 &238).  Usually as 'Grovenor' has said this was done for interlocking reasons (Note*), but the overwhelming majority of double slip ends were worked by one lever but with two separate stretcher bars for the switches. 

 

 

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Many thanks Mike - informative as always! 

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4 hours ago, Aire Head said:

Certainly the Midland in West Yorkshire favoured using single slips to create a trailing connection into the goods yard and simultaneously create a trailing cross over between the running lines.

 

Whilst acknowledging that West Yorkshire is the centre of the universe, I would affirm that even in other less favoured parts of the Midland system, and indeed on lesser lines (the Great Western springs to mind), this arrangement was well-nigh universal at wayside stations on double track lines.

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17 minutes ago, Compound2632 said:

 

Whilst acknowledging that West Yorkshire is the centre of the universe, I would affirm that even in other less favoured parts of the Midland system, and indeed on lesser lines (the Great Western springs to mind), this arrangement was well-nigh universal at wayside stations on double track lines.

 

Whilst I am grateful for your acknowledgement that west Yorkshire is the centre of the world I would like to point out that it is in fact THE world and everywhere else is just additional flavour :P (but seriously I only mentioned West Yorkshire because I can't speak with confidence about anywhere else and your affirmation that the practice was prevalent elsewhere is most informative :blush:)

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As Grovenor pointed out there is another area where it can also be awkward and that is where it can involve interlocking problems (= operational problems) if all 4 switches are worked off a single lever.  

Actually I did not make any mention of the possibility of working both ends (ie all 4 sets of blades) of a slip from one lever as I have never seen this in any interlocked situation or in any situation in the UK. I have only come across it in handworked points in yards in Germany and related countries where they have special point indicators to show the setting. I suspect this usage is the reason Maerklin and Fleischmann use this single lever setup for their slips.

 

PS, on a model I don't see any problem with a single drive stretcher for the 4 blades, I have some I built that way that have been working fine for 40 years now. Seperately adjustable stretchers are needed in full size but would be difficult to arrange in 4mm scale or smaller, might be doable and worthwhile in 7mm.

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23 hours ago, Grovenor said:

Actually I did not make any mention of the possibility of working both ends (ie all 4 sets of blades) of a slip from one lever as I have never seen this in any interlocked situation or in any situation in the UK. I have only come across it in handworked points in yards in Germany and related countries.........

There was a slip with all four ends worked by a single ground frame lever in the yard at Kidderminster IIRC. Not interlocked with anything else i think. Must look it up.

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3 minutes ago, TheSignalEngineer said:

There was a slip with all four ends worked by a single ground frame lever in the yard at Kidderminster IIRC. Not interlocked with anything else i think. Must look it up.

 

This one perhaps?

 

https://upload.wikimedia.org/wikipedia/commons/0/0a/Kidderminster_Goods_Yard_-_geograph.org.uk_-_248565.jpg

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