Templot Club Archive 2007-2020
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posted: 24 Nov 2014 20:40 from: DerekStuart
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Me again... A question (or 3) for the experts- of which there are plenty here! Checkrails on curved track- 10 chains A) Assuming you are coming from a straight section (very low speed so no transition curve (or should there still be one anyway?)) how far should the checkrail lead in from the straight, or does that depend upon speed rating of road? B) I have just read that the checkrail sits proud of the running rail, but I am not 100% sure this was for British track. Is this correct and if so, how far does it sit proud? C) In model form, C&L Exactoscale says to use standard chairs and on each sleeper, alternating between running rail and check rail, with a decorative half stuck on in the appropriate places (I have plenty of 'halves', given how many I've broken!). I wonder if this is the best way to go or whether one should have more working chairs than the other? (Initially I thought 2 for the running rail and 1 for the checkrail, but on the inside of the curve, it's the checkrail that will take the force, not the rail. Any opinions would be appreciated. (PS if anyone has any good tips to get c&l chairs onto the rail- yes I've tapered it and yes I'm doing it on the bottom of the rail). Thanks Derek |
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posted: 24 Nov 2014 20:51 from: alan@york click the date to link to this post click member name to view archived images |
http://www.finescale.org.uk/index.php?route=product/product&path=346&product_id=3937 Or am I missing something? a@y |
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posted: 24 Nov 2014 21:06 from: DerekStuart
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Cheers Alan YOU aren't missing anything.... I thought I'd read the whole of that website too... |
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posted: 24 Nov 2014 21:14 from: DerekStuart
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BTW is there any reason why this chair cannot be used for checkrails on turnouts??? | ||
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posted: 24 Nov 2014 21:17 from: Rob Manchester
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Derek, With regard to threading the chairs onto the rail, you do need to check carefully for moulding flash and remove any found with a scalpel or similar. If you look at the pic of the check rail chairs that Alan suggested( click the pic to enlarge ) you can see that the chairs at the bottom have more flash than those at the top by the way you can't see two clear gaps in the chair for the rail. Any flash left on will make threading the rail more difficult, will make the chairs more likely to break and may also prevent the chair sitting on the sleepers properly as the base may be pushed out from being flat. Rob |
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posted: 24 Nov 2014 21:34 from: allanferguson
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The four end chairs on each sprue have a slightly wider gap to allow for the flare. This is invisible until you get it wrong..... Allan F |
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posted: 24 Nov 2014 21:46 from: alan@york click the date to link to this post click member name to view archived images |
alan@york wrote: http://www.finescale.org.uk/index.php?route=product/product&path=346&product_id=3937Just to fine-tune my answer, these are the P4 versions, there are others with a wider setting for thicker flanges etc. As to the other questions, I've noted that in some cases (my WHL station of Glenfinnan) the check-rail and wing rail of a nearby turnout "merged", so that could be your answer.a@y |
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| Last edited on 24 Nov 2014 21:49 by alan@york |
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posted: 24 Nov 2014 21:59 from: Martin Wynne
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Hi Derek, A few points about check rails on curves.  1. if you follow the prototype rules strictly you find that most model curves require check rails -- which would look a bit daft. 2. most curves sharp enough to need a check rail also have some gauge-widening. In which case you can't use the standard check rail chair because where there is gauge-widening the check-rail gap increases by the same amount as the widening. A check rail is always gauged from the opposite running rail. However, C&L also do a 0.8mm check chair specifically for the purpose in P4: http://www.finescale.org.uk/index.php?route=product/product&path=346_347_348&product_id=3938 3. to help sliding chairs onto rail, try doing it in a bowl of hot soapy water if you don't mind the mess. The soapy water lubricates the process and the heat softens the chair a little. If it is steel rail be sure to dry it off thoroughly afterwards to prevent rusting. 4. in Templot, to create check-railed plain track, use a turnout template instead of a plain track template: a. extend some approach track on the turnout. b. extend the check rail working end(s) back into the approach track. c. shorten the overall template length (F4) to contain only the approach track: 2_241653_380000000.png  2_241654_000000000.png  d. use two of these back-to-back to create the full check rail length. regards, Martin. |
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posted: 24 Nov 2014 22:27 from: Matt M.
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Hi Derek, Checkrails on curved track- 10 chains The Ministry of Transport made continuous check rails mandatory on all curves of 10 chain radius or lower on passenger lines. But they are often fitted on larger radius curves on high speed lines. Remember that check rails are there to stop the tyre climbing over the rail head due to the lateral forces the curve creates for a ridged wheelbase. A) Assuming you are coming from a straight section (very low speed so no transition curve (or should there still be one anyway?)) how far should the checkrail lead in from the straight, or does that depend upon speed rating of road? Yes you can assume a speed restriction upon entering a 10 chain radius curve. If it is a running line with superelevation a transition curve would be preferred as it reduces the transition shock to both rail and rolling stock more effectively than ramping into a plain curve does. The check rail is usually calculated to be in place when the rear inside flange on the longest ridged wheelbase needs to make contact on the rear of the flange to be effective. I believe that the check rail should begin and end about 60 feet from the part of the curve that requires checking. B) I have just read that the checkrail sits proud of the running rail, but I am not 100% sure this was for British track. Is this correct and if so, how far does it sit proud? This depends on the railway company. But in 4 mm it would be hardly noticeable. The theory is that it will give a better bearing surface. But it should also create more drag. C) In model form, C&L Exactoscale says to use standard chairs and on each sleeper, alternating between running rail and check rail, with a decorative half stuck on in the appropriate places (I have plenty of 'halves', given how many I've broken!). I wonder if this is the best way to go or whether one should have more working chairs than the other? (Initially I thought 2 for the running rail and 1 for the checkrail, but on the inside of the curve, it's the checkrail that will take the force, not the rail. Haven’t used the product so can’t comment. But I will note that in real life the chairs used to hold the flared ends were sided. I don’t know if C&L do this. Regards, Matt M. |
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posted: 24 Nov 2014 23:02 from: Trevor Walling
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Hello, I would say the chair half used depends whether it is inside or outside the rail you are referring to. Outside will need a half with a key and the inside obviously not. trustytrev. |
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posted: 25 Nov 2014 13:30 from: Nigel Brown click the date to link to this post click member name to view archived images |
In 3mm/ft, where we don't currently have special chairs, what I do is shave the inside of the running rail chair and the outside of the check rail chair until the check rail can sit the required distance from the running rail. With the chairs I use this works well enough. The same method will of course work for the flaired part of the check rail. Re feeding rail onto chairs, remember to apply a taper to the web part of the rail, ie you need to chamfer all the edges which pass through the chair. The last time I used C&L chairs I didn't find a problem. |
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posted: 25 Nov 2014 14:31 from: DerekStuart
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Thank you everybody for your help. The combined answers from everyone more than answers any questions that I had about checkrails. Being new to this, I am really glad that I decided to make quite a few test modules first before embarking on anything more adventurous. PS- Martin, I found a good article last night that you wrote on bh chair keys. C&L say to alternate this between sleepers on b-d lines, but iiuc from you, the keys are hammered in towards the centre of each panel- ie with the tail of the key pointing back towards the joints? |
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posted: 25 Nov 2014 15:01 from: Martin Wynne
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DerekStuart wrote: PS- Martin,Hi Derek, Practice varies for different prototypes. I have written about keying on several forums over the years. If you post the link I will see if it needs updating. The rule of thumb on single track is that keys are driven into the chair "towards the rail-joint, towards the station, towards the river". On double track they are normally driven in the direction of travel on each track. The intention is always to resist rail-creep. That's important to prevent the essential expansion gaps at rail joints from closing up. For those unfamiliar with bullhead track, when you drive a key in one direction, the hit end remains projecting from it pointing in the opposite direction (the keys are tapered wedges). This has often caused confusion among beginners on forums, by what is meant by "keying direction". regards, Martin. |
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posted: 25 Nov 2014 15:10 from: Tony W
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Hi Martin. It is a useful method of producing check rails often not realised by many. However I have spotted your deliberate mistake. The check rail should of course be on the inside rail of the curve.  Regards Tony. |
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posted: 25 Nov 2014 15:15 from: Martin Wynne
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Tony W wrote: Hi Martin.Doh. I was thinking "that doesn't look right" but couldn't put my finger on it. The senior moments are coming thick and fast these days.  Thanks, Martin. |
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