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posted: 4 Aug 2013 15:53 from: LSWRArt
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Two questions relating to real practice for catch points (or is it trap point?) for sidings: - what decides whether it should be a single blade, or two? For example at Lyme Regis, the catch point exiting the bay had two blades, whereas the catch point exiting the yard had only one blade. - is there any special fixing, or special type of chair for the short point blade (the one between the tracks)? Typically, this rail is only sitting on about 10 chairs, most of which are slide chairs, so what stops this rail moving backwards and forwards? N.B. My question only relates to historic practice (the earlier the better), not what is done today. Thanks, Arthur |
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posted: 4 Aug 2013 18:30 from: GeoffJones
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LSWRArt wrote: Arthur There will be either one or more bolted chairs or block chairs. There are a couple of pictures in "Track How it Works and How to Model It" that show examples of both these approaches. Although the switches may be only a few sleepers long they will often be A switches so quite sharp with plenty of room for the block chairs. Geoff |
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posted: 4 Aug 2013 20:17 from: Martin Wynne
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LSWRArt wrote:- what decides whether it should be a single blade, or two? For example at Lyme Regis, the catch point exiting the bay had two blades, whereas the catch point exiting the yard had only one blade.Hi Arthur, I don't believe there is any hard and fast rule, and it will vary greatly with period and prototype. Very generally, modern catch points are always double. A single catch point is more typical of older track and pre-grouping practice. Very generally, double catch points (or sometimes a full turnout and spur or sand drag) are used as trap points where motive power needs to be trapped -- e.g. for running line loops, engine shed exits, bay platforms, etc. Very generally, a single catch point was used as a trap point for unattended vehicles in yards and sidings where motive power is never or unlikely to be trapped inside. Notice that I wrote "very generally" three times. Someone will now post photos showing the exact opposite. regards, Martin. |
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posted: 5 Aug 2013 20:08 from: LSWRArt
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Hi Geoff and Martin, Thanks for your emails. I enclose an extremely poor quality scan of a photo of Lyme Regis that started this query. (Scanning a printed photo never seems to give good results, presumably due to a conflict between the scanning and the printing process). Going from the right you have: - the bay (to platform and cattle dock) - the main line from Axminster coming from the left and going right towards the main platform - a LH turnout to the run-round loop and sidings. The kick back road from the single slip leads to the engine shed (off photo to the left). The sidings can only be accessed by shunting from the single track main line. Although the line was normally worked one engine in steam, I believe there was nothing to prevent there being two engines in steam at Lyme Regis. The line was fully signalled, had block apparatus and even had a passing loop and double sided platform at Compbyne - half way along the branch. The bay has the double catch point and the yard / run-round loop the single one, which seemed the wrong way round for the potential risk. There is another oddity. The check rail just after the single slip from the loop and yard appears to finish just after the tip of the blade of the catch point, but perhaps that is an optical illusion? 2_051516_300000000.png (Photo is copyright Lens of Sutton and comes from Branch Lines of the Southern Railway volume 2). Regards, Arthur |
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posted: 6 Aug 2013 16:31 from: Judi R
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I can only comment on my experience from the LMR, but we generally used the term Traps to refer to a device intended to trap a wrong movement such as exiting a siding or loop against the signal. A Catch point was a single-blade device to catch wrong-road movements and runaways in the days before the continuous brake. Whether the trap points had double or single blades depended on circumstances. For the above example of Lyme Regis, the exit from the bay platform on the extreme right is angled towards the main line and so a double bladed trap is used to guide errant stock further away from the road it's protecting. In the case of the single slip, the interval is wide enough and the likely speeds low enough to ensure an errant vehicle will not reach the adjacent road. Judi R |
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posted: 6 Aug 2013 16:58 from: Martin Wynne
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Judi R wrote: I can only comment on my experience from the LMR, but we generally used the term Traps to refer to a device intended to trap a wrong movement such as exiting a siding or loop against the signal. A Catch point was a single-blade device to catch wrong-road movements and runaways in the days before the continuous brake.Hi Judi, We've been over this several times before. The term "trap" refers to the function of a set of points. The physical object is generally known to p.w. staff as "catch points" and is shown as such on the manufacturing drawings. Templot is about track, so that is the term we use. See for example the chapter on catch points in David Smith's GWR book*. Trap points may be implemented as a set of catch points, or may be a full turnout leading to a spur or sand drag. In Arthur's picture the catch points on the right are in a passenger line and fitted with a facing-points lock and fouling bar. I'm not aware that a FPL can be fitted to a single catch point without a conventional stretcher bar. Cue a photo from someone proving the exact opposite. *chapter and verse on the various designs and use of GWR catch points: cvr_track_200px.jpg Well worth a read whatever your prototype: http://gwsg.org.uk/GWSG_Publications.html regards, Martin. |
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Last edited on 6 Aug 2013 17:00 by Martin Wynne |
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posted: 6 Aug 2013 18:25 from: LSWRArt
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Thanks for all the helpful comments. It starts to make sense now. Regards, Arthur |
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posted: 17 Aug 2013 21:04 from: DM
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Martin Wynne wrote: Judi R wrote:I can only comment on my experience from the LMR, but we generally used the term Traps to refer to a device intended to trap a wrong movement such as exiting a siding or loop against the signal. A Catch point was a single-blade device to catch wrong-road movements and runaways in the days before the continuous brake.Hi Judi, As a member of the P-Way staff with over 30 years of experience also on the LM, I can confirm that we always said trap points when were talking of a set of points that kept stock in somewhere and talked of catch points when discussing a set of points designed to catch a run away. Regard less of the physical form of the points in question. This may be yet another example of where something is called one thing on one area and something else on another. Or of there being the right (LNWR/LMS/LMR) way, and the GWR way of doing things, |
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Last edited on 17 Aug 2013 21:10 by DM |
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posted: 17 Aug 2013 21:28 from: Martin Wynne
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DM wrote:This may be yet another example of where something is called one thing on one area and something else on another. Or of there being the right (LNWR/LMS/LMR) way, and the GWR way of doing thingsHi David, I did say "generally". It's interesting to refer to the PWI handbooks "British Railway Track". BRT3 (1964 edition) refers to the physical object as "catch points" and "catch roads" throughout. See p.154. So clearly it was not only GWR practice at that date. In BRT4 (1971 edition) all such references have been changed to "trap points" and "trap roads". See p. 150. The sprung trailing catch points on gradients are now called "runaway catch points". So both are right. But for most of the bullhead era popular with modellers they seem to have been called catch points. Except where they weren't. regards, Martin. |
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posted: 17 Aug 2013 21:50 from: Les G click the date to link to this post click member name to view archived images |
DM wrote: ...This may be yet another example of where something is called one thing on one area and something else on another. Or of there being the right (LNWR/LMS/LMR) way, and the GWR way of doing things... Agreed; the recent posts highlight a key aspect about modelling railways, namely that of researching the prototype on which you are basing your model. Then, as Jim Smith-Wright puts it, " model what you see". Confusion can arise if you base your model on several different prototype company locations without working to achieve consistency with reality. Of course if you choose to model a fictional location, you get to decide all that you create and what you call the various components, it being your train-set. Whatever your preferences, the conventions used by Martin in Templot are based on reality, and provide a common frame of reference for discussion here. Cheerydoo Les G |
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posted: 18 Aug 2013 22:56 from: Martin Wynne
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Catch/trap points in action: |
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posted: 18 Aug 2013 23:07 from: Les G click the date to link to this post click member name to view archived images |
OOps! Embarassing ! That's what you get for a SPAD ! Les |
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posted: 20 Oct 2013 11:01 from: stadman
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Wasn't a SPAD, the driver was authorised to pass the signal at danger by the signaller. | ||
posted: 20 Oct 2013 12:58 from: Richard_Jones
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Hi, Does this (type of) incident not warrant an RAIB investigation/report? - I can't see anything on their website. regards Richard |
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