Re: Track and Wheel Standards

Discuss the prototype and how to model it.
Julian Roberts
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Re: Track and Wheel Standards

Postby Julian Roberts » Thu Apr 06, 2017 12:55 pm

Andrew you have mentioned the problem of undergauge track a few times. I think we have you to thank for the Exactoscale Fast Track - did you not bring that in as part of the P4 Track Company's range of products? The Fast Track has proved to be uniquely the range of flexitrack available that is not undergauge in my recent experience.

Whether you did or not, I wonder what you consider to be undergauge on your 1.5m radius 100mph curves? The Fast Track comes in a version 0.2mm wider for curves - do you use that amount of Gauge Widening?

I hope to get back to the weight etc issue subsequently!

Posts in this topic were originally made in "Articulated Beams"and were making that topic somewhat disjointed, I have extracted them into here so please ignore subsequent post headers that show the origin.
Thanks, Keith

andrew jukes
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Re: Articulated beams?

Postby andrew jukes » Thu Apr 06, 2017 2:23 pm

Julian Forget speed for the moment - providing a running clearance for wheelsets is important whatever the speed. The design parameters I use on my own layout are: minimum radius 1200mm; all curves to have transition curves; track to accommodate Pacifics with scale 6’ 8” drivers and fairly limited sideplay; back to backs gauged at 17.82mm.

I use Fast Track for behind the scenes track and New Track bases for the proper sections. For anything under 1500mm radius, I aim to have at least +0.2mm of gauge widening. In the transition curves, you have to decide where to switch between +0.0 on straight track and the +0.2 of the circular curve. There’s no point in trying to be too clever here - I switch from standard Fast Track to gauge widened about halfway through the transition, making sure the switch is halfway along a panel and not at a rail joint. This way the rails themselves do some spreading of the gauge adjustment.

I mentioned I use a back to back of 17.82mm. With this (and with the exact scale 17.87mm) gauge widening is more important than it would be when using the original P4 standard of 17.67mm. The Society recommended back to back of 17.75mm falls somewhere in between. Differences in back to back translate pretty directly into different requirements for gauge widening. If you are using curves a lot tighter than my 1200mm radius and still using large-wheeled 6-coupled locos, then you are likely to need more gauge widening (and some, even if using the 17.67mm back to back gauge). On the other hand, if it’s short wheelbase 4-coupled locos (or Bo-Bo diesels) and short wheelbase 4-wheeled wagons, you can probably forget gauge widening.

In the end, whether through gauge widening, choice of vehicle, provision of sideplay or choice of back to back, the aim is to have all wheelsets with that little bit of running clearance everywhere on your layout. You can usually tell whether you’ve got it just by gently feeling for wheelset freedom with the vehicle sat on the track.

Andrew

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Will L
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Re: Articulated beams?

Postby Will L » Fri Apr 07, 2017 12:50 pm

Julian Roberts wrote:... on the club layout there is a 4ft radius approx curve that catches some stock out, but I regard mine as a failure if it fails to negotiate it, and I remedy it. Currently I am trying to remedy the curve to be less troublesome by increasing the GW from what the triangular gauge gives, to 0.2mm, and putting in a (very) little cant. Time will tell if that is sufficient answer to the problem. Next would be adding a checkrail. But I suspect the issue may be there is insufficient transition..


While adding a bit of GW shouldn't do any harm, on a 4 ft radius curve laid with the triangular track gauge, it has to be doubted it will do any good. Remeber this?. While an absence of Gauge Widening where it is required will certainly cause problems, there's absolutely nothing which says putting in more where it isn't required helps anything.

Cant on the other hand is much more of an issue, if you get an occasional vehicle falling off on a curve that most similar ones have no problem with, then unrecognised changes in the amount of cant (i.e. track that isn't as flat as it is supposed to be) is very Iikely to be a significant part of the problem. Delivering to the dirt any wagon who's suspension (or lack of it) is insufficient to keep the wheels firmly on the track through the change in cant. Exactly the issue that has Martin G fitting EM gauge wheels. Trying to add cant in a controlled way can be quite tricky. Where people want to add super elevation through a curve, most apply the cant by adding a twist to the track base on which the track is laid as this tends to avoid sudden significant changes. Trying to lift and resolder the outside rail uniformly a little higher round the curve is more likely to add to the problem than cure it.

andrew jukes
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Re: Articulated beams?

Postby andrew jukes » Fri Apr 07, 2017 1:43 pm

Without being too pedantic, it's twist that is the real problem. A canted circular curve has no twist and should pose no problems however much cant is applied. But you can’t connect a canted circular curve to an uncanted straight (often described as tangent) track without introducing twist. The transition is where cant builds from zero on the straight to the full amount in the circular curve. Without a transition curve the temptation is to add cant too quickly, creating excessive twist.

The prototype has strict rules on acceptable amounts of twist/metre and we need to be similarly limited.

The scaling effects discussed earlier not only mean that our models can race round small radius curves but also mean that cant is hardly needed. If you put the scale maximum prototype cant of 2mm on the outer rail, it will both look silly and the trains will run with flanges firmly in contact with the lower rail. I think some cant is important for trains to sit properly in the curve but 0.5mm is probably enough for that.

In terms of how to do it, I favour building it into the trackbed.

Regards

Andrew

Julian Roberts
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Re: Articulated beams?

Postby Julian Roberts » Fri Apr 07, 2017 2:50 pm

Andrew regarding your post yesterday on track.

You said you use a B2B of 17.82mm. As that is 0.15mm more than the P4 minimum of 17.67, does the check gauge still function or do you move it nearer the stock rail?

To quote the CG range in the standards, and flange thickness of 0.4
18.15 - 0.4 = 17.75
18.2 - 0.4 = 17.8

so to my no doubt untutored eye (and very dodgy maths) there might be some nibbling at the V....?

But with a flange of 0.35 (from the range in the Standards) and the larger CG figure you are clear - though with a lot less to spare than some of us old hat guys at 17.67...?

Thank you for making sense re Gauge Widening.

Do you have pointwork on this 1500mm radius with 0.2 GW, and if so what happens to the GW through the switch and crossing?

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Re: Articulated beams?

Postby Philip Hall » Fri Apr 07, 2017 6:00 pm

At the risk of incurring some wrath for being still a little off topic, here's my thoughts on gauge widening.

It is necessary, because our wheels are never going to be absolutely true on their axles. There is going to be a bit of wobble sometimes. Not always, but sometimes. Wheels which are put on their axles seemingly perfectly will inevitably move. I'm sure I've said this before (many times?) so apologies if this is a repeat! So a bit of slop in the gauge (sorry to put it like that but that is what it is) helps us here. My feeling is that if wheels are set at the upper dimension and they move/wobble, they can move outside of the maximum, so bad news. I use 17.7mm ( because that's what my gauge measures) and that gives me a little leeway on straight, or nearly straight track. On curves, I either use the three point gauge or widened Fast Track. I actually am going to use the widened Fast Track on ever so slight curves as well, simply because I bought too much of it years ago, when my layout was going to be in a smaller room and I was contemplating 3'6" radius curves instead of the 4'6" I am now able to enjoy.

C&L thin sleepered track has seen some variation in gauge, though not as much as I have had in the past, and does sometimes narrow when you bend it. Early examples I had did actually widen as you bent it, which was what was supposed to happen. It helps for it to be glued down firmly so it can't move, which I'm not really keen on because it then is dead rigid, and noisy. The latest stuff I had was purchased more than ten years ago and seems to have held its gauge pretty well on my test track. I intend using it in sidings, and if it's a bit tight I shall have a go at the sleepers with a blunt chisel down amongst the weeds!

Finally, I do fancy a little bit of superelevation, just for the look of it, but only a little. Using the Fast Track, I shall just pack underneath the edges of the sleepers with writing paper over a long length to introduce a little. The sleepers are rigid enough to allow this. Andrew's 0.5mm strikes me as a good maximum. This will be experimental as I shall be running a lot of rigid RTR chassis amongst some of the home brewed variety. If rigid things fall off, the paper comes out and I leave it flat.

Perhaps I should say that the railway is going to be of some size, hence I have to make time for some short cuts...

Philip

Julian Roberts
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Re: Articulated beams?

Postby Julian Roberts » Sat Apr 08, 2017 7:00 am

Andrew I wonder if you saw my post asking about your Check Gauge and GW through pointwork?

With my lightened centre axles ( or intermediate ones in the case of my 0-8-0) I have avoided putting motor and gearbox on these in the expectation of the effect you have just described.

Triangle drawings later.

andrew jukes
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Re: Articulated beams?

Postby andrew jukes » Sat Apr 08, 2017 1:23 pm

Julian - I set all my check rails with an S4 (18.25mm) Check Gauge. This avoids the conflict you were concerned about.

Using Exactoscale P4 check rail chairs, which are intended to give a 0.68mm flangeway, you end up with a little gauge widening in the crossing area, but this has never seemed likely to be a problem. Using the Exactoscale turnout bases, a wee bit of bodging may be needed to let the check rail chairs sit slightly wider on the pips.

Where it all gets interesting is when you start building curved crossings and want to keep to ones chosen rules for gauge widening. The attached photo shows a diamond with both roads at 1300mm radius. It is behind the scenes so not made to look good but has to perform reliably as it is where the main routing options for the layout take place. Digest 1.2 is very clear on the approach to use - "Gauge widening should not be applied to any sections of pointwork where CG, CF or BC dimensions are specified." - so in applying gauge widening you’re really on your own. What I’ve done is gauge at +0.2mm, set the check rails at 18.25mm and provide generous crossing flangeways. Condition 4 of Digest 1.2 is definitely violated but this merely means a slightly bumpy ride. The crossing has worked really well with only one derailment in the early days because a check rail was not set quite far enough from the crossing nose. That said, I haven’t run decently long trains of 4-wheeled wagons over it, which would be a proper test.

Checking the gauge widening I’ve actually got on my 1200mm (Fast Track) and 1400mm (New Track) curves, the Fast track is probably +0.25mm as there is a little play with an Exactoscale 2-band gauge and the 3-band gauge is slightly pinched. The New Track (26 sleepers/60’ panel) is +0.2mm. The track has been down for a good few years now so today’s measurements were a good check on the track’s stability.

Regards Andrew
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Julian Roberts
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Re: Articulated beams?

Postby Julian Roberts » Sun Apr 09, 2017 7:27 am

Fantastic Andrew. Amazing curved crossing looks or no looks. So nice to read someone making sense of all this. I will get back to triangles but as a quickie I never asked the obvious question, why 17.82 and associated changes rather than plain vanilla P4?

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Re: Articulated beams?

Postby andrew jukes » Mon Apr 10, 2017 11:08 am

Why 17.82mm?

The MRSG devised the P4 standards in the 1960s and chose a B to B of 17.67mm. The reasons for this choice are not clear but may have included a wish to avoid the ’complication’ of gauge widening. It quickly became obvious that 17.67mm allows lots of slop on straight track (try rotating a short wheelbase 4-wheel wagon with 17.67mm B to B and see what lateral displacement results at the buffers).

Ray Hammond showed there could be some advantages in a wider B to B, using 17.87mm, now generally known as S4. The Society (not sure who exactly) decided it would be good to take out some of the slop but did not want conflict with MRSG members. The solution was to recommend (in Digest 1.2) use of a B to B at the max. of the official P4 standards i.e. 17.75mm, and this is what gauges sold by the Society and the Exactoscale P4 gauge should measure.

My view is that if one is happy building appropriate gauge widening into track and does not have lots of turnouts already with check rails at 18.15mm then there are few downsides in going slightly wider than 17.75mm.

One factor to consider is what is achievable in setting B to B. Assembling wheelsets on an Exactoscale-style gauge is unlikely to result in wheelsets under the gauge dimension but can rather easily give a slightly over gauge result. My aim is that a wheelset should slide smoothly onto the gauge but, when released, should not drop further under its own weight. If a little loose, I try it on a Ray Hammond 17.87mm L gauge. If there’s any play on that - it's a reject. Using a 17.82mm gauge thus makes practical sense with this approach.

The extent of slop in the 17.67mm B to B is highlighted by Martin Goodall's persistent advocacy of the use of EM wheels on P4 track. Thicker flanges is one way of reducing the slop but a wider B to B makes more sense to me (and avoids those clunky-looking EM tyres and flanges).

Regards Andrew

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Re: Articulated beams?

Postby Julian Roberts » Tue Apr 11, 2017 6:38 am

Using Exactoscale P4 check rail chairs, which are intended to give a 0.68mm flangeway, you end up with a little gauge widening in the crossing area, but this has never seemed likely to be a problem. Using the Exactoscale turnout bases, a wee bit of bodging may be needed to let the check rail chairs sit slightly wider on the pips.


Andrew now (phew!) we have sorted out those axle weights thanks so much for your and Will's help I have much remaining curiosity regarding
track questions. The first one is, to blow another cobweb out of my mind, I thought with any GW on
curved track or on pointwork that the check rail was supposed to stay the check distance from the opposite rail, and the check flangeway widen from its normal value according to the amount of GW.

If you have an increased CG does that not mean you have a reduced check flangeway? - so that on the straight route of a turnout you have a 0.55 - 0.58 check flangeway and a standard P4 crossing flangeway of 0.65 - 0.68?

I have not asked whether you stick to the normal P4 crossing flangeway value.
I can see it would not matter, if one wanted to use the Exactoscale normal checkrail chairs, that the gauge goes that bit wide on the straight route too, but is that what you do?

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Re: Articulated beams?

Postby andrew jukes » Tue Apr 11, 2017 10:51 am

Julian - The most important dimension in a common crossing is the check gauge (CG). It needs to position the check rail far enough from the crossing nose so there is no chance of the flange of a correctly gauged wheelset contacting the crossing nose. For a 17.75mm BtoB wheelset, that means a CG of 18.15mm; for a 17.87mm BtoB wheelset, that means a CG of 18.25mm.

If you want a continuous check rail to keep the outer flange from grinding along the outer rail, the numbers are the same.

Track gauge (TG) is not particularly important in any of this - except it must never be less than 18.83mm. If you widen the track gauge keeping CG constant, the flangeway behind the check rail will increase. On a gauge widened curve, this is what you should see (and why I hoped Exactoscale would produce a decent 0.9mm check chair). With a common crossing and the correct TG, you should see the ‘standard' flangeway (in P4, 18.15mm + 0.68mm = 18.83mm) (in S4, 18.25mm + 0.58mm = 18.83mm). But note that the check rail flangeway is not a critical dimension - it is CG that matters.

You can also play a bit fast and loose on a common crossing with the crossing flangeways (CF). The potential showstopper here is that a narrow CF with the wrong combination of CG and BtoB can result in a wheelset jamming as the backs of the wheels simultaneously rub along the wing rail and the check rail (a 0.58mm CF and 18.25mm CG will leave zero clearance with a 17.67mm BtoB). You can widen CF quite a lot without a serious derailment risk but the crossing starts to get very bumpy as the wheels stop being properly supported as they run across the gap between the knuckle and the crossing nose.

Where I have used Exactoscale pre-assembled crossings (which we hoped would have a CF of 0.65 - 0.68mm) that’s what I use. When building my own, I work with a 0.58mm gauge but never let it end up a tight fit.

Regards Andrew

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Re: Articulated beams?

Postby andrew jukes » Tue Apr 11, 2017 11:24 am

I should have said that obtuse crossings require more care because of the need to steer the wheelsets so they don't go the wrong way. It's also important to exercise tighter control in complex formations where there may be common crossings in both rails, opposite each other.

In both cases the basic principles continue to apply but there is less scope to play fast and loose with some dimensions.

Andrew

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Russ Elliott
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Re: Articulated beams?

Postby Russ Elliott » Tue Apr 11, 2017 2:32 pm

andrew jukes wrote:What I’ve done is gauge at +0.2mm, set the check rails at 18.25mm and provide generous crossing flangeways.

Pragmatic and utterly sensible, Andrew (if a trifle devious!) A good example of where a little bending of the rules is good for a particular application.

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Re: Articulated beams?

Postby Julian Roberts » Wed Apr 12, 2017 6:21 am

Andrew have I got this right - on the straight road of a turnout where you are using Exactoscale chairs your Track Gauge goes 0.1 wide because your check gauge is 0.1 wider than the standard P4 one. Where you make your own pointwork without Exactoscale components, again on the straight road, both crossing and check flangeways are 0.58, with the crossing flangeway not tight, and your TG is 18.83

On the curving road of a turnout those Exactoscale chairs are giving you 0.1 GW so if you need 0.2 GW on your below 1500 radius curves what do you do there if you still want to use the chairs - cut them I suppose...?

I should say I have no experience of using Exactoscale components and I have only soldered trackwork experience so far.

I am not asking because I am going to go the same way as you but because I want to be sure I understand the principles involved.

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Re: Articulated beams?

Postby andrew jukes » Wed Apr 12, 2017 10:40 am

Julian - Yes, that’s right, though you differentiate between the straight and ‘curved’ roads in a way that’s not necessary. In the crossing area, turnouts are generally straight on both roads.

If building a turnout with a curved crossing on a curve that’s sufficiently tight to require 0.2mm gauge widening and using Exactoscale checkrail chairs, I wouldn’t cut the chairs. I would either set them using the 18.25mm CG and not worry about the local relative reduction of 0.1mm in track gauge or set them using a +0.2mm TG, knowing that a 0.1mm wide CG wouldn’t be a problem.

Andrew

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Re: Articulated beams?

Postby Julian Roberts » Thu Apr 13, 2017 4:42 am

A diversion to the land of lower quadrants, turnout switch joggles. At the Bridgnorth end of Highley station the curve seems to sharpen appreciably just at the end of the platform briefly. Not sure if I imagine the checkrail gap widens, as per instructions as the gauge widens.

20170412_152543.jpg

Julian Roberts
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Re: Articulated beams?

Postby Julian Roberts » Thu Apr 13, 2017 5:17 am

And talking of joggles could this be one at the north end of platform 1 at Redhill? Zouthern territory but GWR moguls once used to roam regularly here on Reading services.

The stockrails seem to joggle but the switchrail wear pattern doesn't look as though the wheel bears on it at its tip. Other points at Redhill don't show joggling tendency.

A nice bit of trackwork quite like your hidden one Andrew, looking as though the new platform (0?) works may render obsolete.

Dunno how to orientate these pix correctly.

20170319_111044.jpg
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Julian Roberts
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Track and Wheel Standards

Postby Julian Roberts » Sat Apr 15, 2017 8:10 am

Andrew could one say your standard is S4 with a narrower BB setting?...S4-lite perhaps?

With S4 flangeways you have 17.67 space for your 17.82 wheelset backs.. So that's less than the prototype ( at 17.85-87 as far as I recall) but clearly it's enough at 0.15. But where you set the check gauge 0.1 wide on a GW curve when using Exactoscale chairs you have only 0.05...and the outside drivers of a large wheeled Pacific will be going at a tangent round this bend...

But here you use Exactoscale crossings too I take it so assuming they are at 0.68 you are back to 0.15 BB clearance.

Is my maths right so far?

If you have this 0.2 GW and the checkrail at 18.35 with Exactoscale chairs your wheel back at 18.22 will hit the checkrail and be deviated 0.13, rather
than the more gentle 0.03 when set on your handmade trackwork, but does this bother you? It
seems to me that while real passengers would find that uncomfortable model ones won't mind very much, and while real trackwork and wheels
might be damaged depending on speed, model ones won't be even at 100 scale mph, nor will they derail.

Again I am asking this simply to be sure I understand and thank you for taking the trouble to reply to my earler simpleton questions.

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Re: Articulated beams?

Postby Julian Roberts » Sun Apr 16, 2017 6:53 am

andrew jukes wrote:Where it all gets interesting is when you start building curved crossings and want to keep to ones chosen rules for gauge widening. The attached photo shows a diamond with both roads at 1300mm radius. It is behind the scenes so not made to look good but has to perform reliably as it is where the main routing options for the layout take place. Digest 1.2 is very clear on the approach to use - "Gauge widening should not be applied to any sections of pointwork where CG, CF or BC dimensions are specified." - so in applying gauge widening you’re really on your own. What I’ve done is gauge at +0.2mm, set the check rails at 18.25mm and provide generous crossing
flangeways. Condition 4 of Digest 1.2 is definitely violated but this merely means a slightly bumpy ride. The crossing has worked really well with only one derailment in the early days because a check rail was not set quite far enough from the crossing nose. That said, I haven’t run decently long trains of 4-wheeled wagons over it, which would be a proper test.


Andrew further to my previous questions above, on the crossing nearest the camera in the photo you attached to this post I can see the crossing
flangeways are wider than the check flangeway
(though I can't tell if they are wider than P4 0.68) so how did you establish what width they should be? Re the Digest 1.2 surely all of your points with GW applied violate the condition you quote?
Looking at the diamond all the flangeways look
more equal so does the same apply there but to a different degree? On another post you talk about
more complex formations needing greater care. Does this diamond come into that category? At 17.82 BB does your S4 lite (as I put it) standard meet the criteria to solve the issue on K crossings which Ray Hammond showed and which I have never quite understood without a drawing although a recent S4/P4 thread came close. A train of coaches consists of several bogies that are similar to a 4 wheel wagon so why is a train of wagons a better test? - the instability I take it. Lastly your description of BB gauge use implies to
me your standard is 17.82 - 87 rather than bang on 17.82, is that right, so a practical widening of the prototype tolerance window in the narrower direction ?

Apologies to you and any reader for my tiresome questions, and Easter Greetings.

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Re: Articulated beams?

Postby andrew jukes » Tue Apr 18, 2017 3:02 pm

Julian - Whatever we do, please don’t try to start attaching new names to standards. Two are enough - P4 for the original MRSG defined standards which encompass the Scalefour Society’s recommendation to set BtoBs at the P4 maximum of 17.75mm; and S4 as used by RayHammond and described by Digest 1.2 as 'Use of 4mm scale equivalent dimensions’.

I would regard a choice of standards that use of an 18.25mm CG and BtoBs > 17.82mm as falling into the S4 category. Fiddling with the standards to produce something that meets a specific need is always likely to happen but what results is not a new ‘standard’.

What would help is for those who (erroneously) thought that P4 was a protected term and felt forced to use S4 instead would now adopt the general usage that I describe above. The protected term was ‘Protofour’ - and I’m not sure anybody uses that now. Anyway, I’m not sure who now would object to any of these terms being used - we have come a long way from 1975.

I’ll come back on the dimensional issues in a day or two - but my general feeling is that you’re starting to worry too much about the second decimal place of mm!

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Re: Articulated beams?

Postby Julian Roberts » Wed Apr 19, 2017 11:10 am

Andrew you probably realize from my beams 'calculations' that my approach is very rough and ready. I can do the maths on these track questions (just) but know from experience I am lucky if I get anywhere near within 0.1mm accuracy in practice both with track and BB!

Keith will this thread discontinue or run in parallel? Happy to go with whatever you wish, speaking for myself.

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Track and wheel standards

Postby grovenor-2685 » Sun Apr 23, 2017 8:14 am

As well as being out of place in a discussion on vehicle suspension the discussion above does raise some issues with the standards that perhaps need a bit more exploration. i will come back to it after a bit of preparation.
Regards
Regards
Keith
Grovenor Sidings

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Re: Track and Wheel Standards

Postby Julian Roberts » Mon Apr 24, 2017 5:27 pm

andrew jukes wrote:
I mentioned I use a back to back of 17.82mm. With this (and with the exact scale 17.87mm) gauge widening is more important than it would be when using the original P4 standard of 17.67mm. The Society recommended back to back of 17.75mm falls somewhere in between. Differences in back to back translate pretty directly into different requirements for gauge widening. If you are using curves a lot tighter than my 1200mm radius and still using large-wheeled 6-coupled locos, then you are likely to need more gauge widening (and some, even if using the 17.67mm back to back gauge). On the other hand, if it’s short wheelbase
4-coupled locos (or Bo-Bo diesels) and short wheelbase 4-wheeled wagons, you can probably forget gauge widening.

In the end, whether through gauge widening, choice of vehicle, provision of sideplay or choice of back to back, the aim is to have all wheelsets with that little bit of running clearance everywhere on your layout. You can usually tell whether
you’ve got it just by gently feeling for wheelset freedom with the vehicle sat on the track.

Andrew


Feeling for the amount of running clearance is not quite straightforward because of the similar play between wheels and vehicle needed to achieve free rotation of the wheels!

Your comments could be taken to imply that (your design?) Fast Track is really designed for S4, and for P4 undergauge track is OK with the minimum BB 17.67, and Fast Track gauge widened version unnecessary on curves...?! However it seems to me that Philip Hall's pragmatic comment is the most useful guide to answering that question. His description of the fallability of BB staying constant, coupled with my own fallability in getting it particularly accurate in the first place, shows it is sensible to use the Fast Track as specified for P4 as well as S4.

My experience with my dodgy technique is that BB might be up to 17.80 and down to 17.50 but (this
is how the topic is linked to beams) with enough weight in the right place no harm befalls. Somehow soldering track is easier to do more exactly than getting BB perfect, and it is more stable, and it seems sensible to expect some wheels may be wider apart than the minimum. Strangely no harm seems to occur on K crossings with narrow to gauge 17.5ish wheels, but perhaps that is just luck.

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Re: Track and Wheel Standards

Postby Julian Roberts » Sat Apr 29, 2017 10:09 am

grovenor-2685 wrote:As well as being out of place in a discussion on vehicle suspension the discussion above does raise some issues with the standards that perhaps need a bit more exploration. i will come back to it after a bit of preparation.
Regards


Keith some of the discussion on P4 vs S4 - Pro's and con's is on similar questions, should that be copied onto here too?


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