Templot Club Archive 2007-2020
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posted: 16 May 2011 19:55 from: Brian Nicholls
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Hi All, I’ve been working on an irregular double slip (yes you read it right, an irregular) for New Street, and have a slight problem in knowing how much one can move the switch blades from a position where the clearances are not really viable, to a more practical position. I have attached below a screenshot of what is needed. Bearing in mind prototype practices (I’m working in P4), I believe, that the main limitation may lie in the sliding chairs near to the tips of the switch blades, these must be of either a particular double slide type to accommodate for the moving paired switch blades, or that two single slide chairs have to lie, and are butted together slide to slide, across the gap at the blade points. I can only assume, that the prototype sizes of these chairs must be fairly fixed and defined, otherwise it could mean ‘specials’ have to be made which I very much doubt. As you can assume I am limited in knowledge on this particular point and would be glad of any help or suggestions, I do however, have a drawing of a single slide chair as used by the LNWR, but this somehow does not seem to fit the bill.  Hope someone can help. All the best, Brian Nicholls. 1853_161453_200000000.gif  |
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posted: 16 May 2011 20:06 from: Martin Wynne
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Hi Brian, You have the slip switch much too close to the V-crossing. You can't have the other blade opening behind the check rail. Have you tried the slip switches provided in Templot for the purpose? Peg them on to the TCP and MCP peg positions. They are not based on any specific prototype, but will get you close to the required position for most. regards, Martin. |
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posted: 16 May 2011 21:44 from: Brian Nicholls
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Martin Wynne wrote: You have the slip switch much too close to the V-crossing. You can't have the other blade opening behind the check rail. Hi Martin, Many thanks for your speedy reply.  I agree entirely with what you say about the switch being much too close to the knuckle of the V-crossing, that was the reason for my question. However, I rather think I asked the question in the wrong way, realising that one could move in the direction shown, as far as one likes, and I should have really enquired how close, in prototypical, and for that matter practical, purposes can I get the switch blade tips to the knuckle of the V-crossing. Again I was considering the limitation of the space available for the fixing chairs to accommodate both moving switch blades, and what would these chairs or chair be like. Have you tried the slip switches provided in Templot for the purpose? Peg them on to the TCP and MCP peg positions. They are not based on any specific prototype, but will get you close to the required position for most. I will certainly give your suggestion a try and see what results I get. Also of course I can try using the moving peg (slide along centre line etc) to find a suitable position for the switch blades. But referring back to the latest above mentioned question in blue, I would like to try and get the blades as near to the prototype as possible, so in this case again it begs the question what designers and gangers do in the prototype world. I suspect that they would probably use two slide chairs mounted slide face to slide face, and be as close as possible together, bearing in mind sufficient area of timber for the fixing bolts at the two slide ends of the chairs, but this is only a guess on my part. Finally as I have been working on this, I have taken lots of screen shots and made notes in the possible light of producing another, albeit long winded, tutorial way of making a double slip, mainly for the beginner using Templot, so needed to get the switch positions right, as near as possible that is, particularly since the tutorial will be on irregular double slips. Many thanks again martin for your help. All the best, Brian Nicholls. |
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posted: 16 May 2011 22:09 from: Martin Wynne
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Brian Nicholls wrote:I should have really enquired how close, in prototypical, and for that matter practical, purposes can I get the switch blade tips to the knuckle of the V-crossing.Hi Brian, A thousand ifs and buts, but at the minimum you need 12" (or at the very least 11") between the stock rails at the centre of the timber carrying the blade tips. This allows room for both blades to stand open at the tip and have the tips sufficiently thick at the foot to be robust. For a model you can get away with a bit less by driving all 4 blades off the same stretcher, so that only one centre blade is ever open at a time. This corresponds to most actual interlockings, but for safety in maintenance it must be possible to have both blades open if necessary. Sorry I can't write a detailed reply at present as I'm a bit too busy with coding.  regards, Martin. |
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posted: 16 May 2011 23:15 from: Brian Nicholls
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Hi Martin, Many thanks again for a speedy reply, and sincere apologies for taking up your time in answering my questions, I know Paul, Rod and others are waiting eagerly for the beta version of the new pug, so again, apologies. The information you have provided, for which I thank you, will suffice for the moment, as I had already made assumptions that the absolute minimum possible gap distance for a pair of blades could only be with one blade closed and the other open thus giving a min gap of 4.25” + 4.25” = 8.5” proto which I consider is too close. But the dimensions you have quoted make a little more sense, so will be guided, for the time being, by those. I don’t think I will bother to go to having all four blades driven of the same stretcher, even for New Street, , as I would like to keep as near to proto as possible, and any resulting tutorial from this work, as standard as possible to meet all types of double slips that anyone may come across irrespective of scale or modelling preference, whether it be fine scale proto or simple fun railway modelling just to run trains. Perhaps in the distant future, you would be kind enough to send a detailed reply to the question, just for completeness and my peace of mind, but obviously not at this time, and there is no need to apologies for not doing so now. Unless there is someone else out there that knows the answer to the question !! Many thanks again Martin, and apologies for taking up your valuable time, All the best, Brian Nicholls. |
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