Wagon Suspension

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jim s-w
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Re: Wagon Suspension

Postby jim s-w » Tue Jan 19, 2010 12:46 am

DaveyTee wrote:I'm not too worried as to whether it strictly meets all the defined standards.


Hi David

There are only really 2 sets of standards. One for track and one for wheels. If you use one and not the other you are only using half of the standards laid down. The point is the standards are the way they are for a reason. They are not just a pile of numbers plucked from thin air. The whole thing is a system that is designed to work together. Why change one part of a system? Its like 00. Its a system designed to work together and it does just that very well. When you change part of the system (use finer wheels for example) suddenly the system breaks down and no longer works as it should. Your new fine wheels fall into the gap going through a vee.

Theres no doubt you can use EM wheels on P4 pointwork but I do think Martin underplays the extra hassle it causes. For example you can buy a Bachmann Mk1, some Branchlines wheels, pop them in and you have a P4 mk1 that runs just fine. With an EM wheel you have to file a fair amount off the insides of the bogie to get the wheels in. In fact ( I know this because you have to do filing if you use Alan Gibson or Ultrascale P4 wheels) its actually easier just to chop the sides of the bogie off and stick them to a brass, compensated or sprung bogie instead. Having converted a lot of things to P4 I cant remember many that will allow an EM wheel in without filing. I do think the tolerance Martin refers to is somewhat skewed. It sounds a bit like a comparrison between the wide end of the tolerance for a P4 wheel compared to the narrow end of the tolerance for an EM wheel. Very few wheels are either of these.

The fact is that the easy things to convert this way, coach bogies, 10ft wheelbase wagons etc are the least likely to give you any grief with a straight swap for P4 wheels anyway. How bad does track have to be for a 10ft WB wagon to fall off. Theres little point in doing all that if you cant get the wheels into the loco that will pull them.

GIve it a go and see what you think. I did years ago. I converted everything back to proper P4 wheels pretty quickly though. I applaud Martin for getting it to work and for all the extra hassle in doing so. I took the easy route and stuck to the standards.

Cheers

Jim

Terry Bendall
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Re: Wagon Suspension

Postby Terry Bendall » Tue Jan 19, 2010 8:28 am

martin goodall wrote:If you were setting out with a clean sheet, then you might consider building the layout in EM gauge as an alternative to P4 (or possibly even in 00 gauge).


Yes you might, but then, with a bit more thought you might not. When I have been on the Society stand at exhibitions I have had several EM modellers say to me that they wished that they had gone all the way to P4 but it was now too late. There are some very good EM modellers and some very good EM layouts but why go to all the trouble of changing wheels and building your own track when it is not the correct gauge?

DaveyTee wrote:I chose P4 because 18.83 track looks right, but I would like to get a layout built and up and running during my lifetime and provided that what I make looks right and performs well, I'm not too worried as to whether it strictly meets all the defined standards.


The track may look right but the wheels won't be. Of course at an exhibition, and with normal viewing distances, it is not easy sometimes to tell the difference between EM and P4 but the builder knows.

In the end it depends on what you want out of the hobby. If you want to mix EM wheels on track made to P4 standards and you can get it to work - something that surprises me, then fine. Its your train set and you do what you want. Some people of course are quite content with 00 and some people even built their own 00 track which to me seems a complete waste of time - why spend time building track which is not to the correct gauge but its your train set.

P4 wheels on P4 track do work - that has been proved time and time again. You need more care than when working in 00 and a bit more than working in EM, but not that much more. On Staverton, where some of the track is over 30 years old and is not top quality I have got a set of 8 Bachmann coaches fitted with P4 wheels to run the full length of the layout - 28 feet, and over turnouts without de-railing and with no compensation. So some things will run without any compensation or springing at all. I have yet to try a four wheel wagon without any springing or compensation but I will give it a go sometime.

So if Martin wants to try and run EM wheels on P4 track and he can get it to work then fine. Don't call it P4 which he isn't and it ain't, but its his train set. Personally I wouldn't bother but then that's my view. I would rather try to get it all right - wheels, track, signalling, operation, match of stock, etc.

Terry Bendall

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Re: Wagon Suspension

Postby martin goodall » Tue Jan 19, 2010 10:06 am

Just to clarify a couple of points.

First, my track is built to P4 standards. Flangeway and check rail cleaances are all within P4 tolerances; they have not been adjusted in any way to accommodate the EM-profile wheels. I can run P4 rolling stock on my layout, and I still have some vehicles which have P4 wheelsets, but I am currently working my way through them substituting EM wheels set to P4 back-to-back gauge, just to get that little bit of extra reliability that the deeper flanges of EM wheels give you. (They are only 0.25mm = .010 ins deeper, but it seems to make all the difference.)

As regards a name for this 'bastard' standard, I thought of EMF, but that has been used before and meant something else, so I call it "Coarse-scale P4"! It is P4, because the track, as I have said, is exactly to P4 standards; it is just the wheel profile that's different.

Let me issue a little challenge. Select one item of P4 rolling stock which has shown an occasional propensity to derail (not all over the place, which suggests that there may be something seriously awry, but one that just occasionally misbehaves itself). Get hold of some EM wheels, regauge them to P4 back-to-back and pop them in. Then see what happens. I think you will be surprised at how sure-footed this vehicle then becomes.

Where the use of EM-profile wheels really comes into its own is in converting RTR rolling stock to run on P4 track. Its quick, it's easy and it works. That, of course, is where we came in - in suggesting answers to the query posed by Julian Roberts. I can't help feeling that some of the other solutions that have been suggested are consderably more time-consuming and certianly a lot less easy than mine, even though they may be intellectually more satisfying.

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jim s-w
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Re: Wagon Suspension

Postby jim s-w » Tue Jan 19, 2010 11:03 am

Hi Martin

The point being made over and over by others is that MOST rtr stuff will run just fine with a straight wheel swap for P4. I have a rake of 18 HEA's that are converted just that way and they have never given any problems, either pushed or pulled. These wagons have a relatively long wheelbase.

Like I said I did try the EM wheel route years ago and most of my RTR stuff wouldn't accept EM wheels set at P4 without a lot of filing to the W irons or bogies.

Its all very well saying that EM4 (or whatever you want to call it) is more relaible but please don't claim its as easy as a straight wheel swap because in my practical experience you are over simplifying the matter.

Just to re-itterate and get the topic back on track, do a straight wheel swap for P4 wheels and see what happens. Most of the time it will work just fine, if it doesn't then look at other options.

Cheers

Jim

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Flymo748
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Re: Wagon Suspension

Postby Flymo748 » Tue Jan 19, 2010 11:22 am

martin goodall wrote:Just to clarify a couple of points.


Hi Martin,

Thanks for the extra clarification. I don't think that it persuades me to change (back) as P4 works for me as a "package" but could I tease out one or two more points for the sake of full understanding?

martin goodall wrote:First, my track is built to P4 standards. Flangeway and check rail clearances are all within P4 tolerances; they have not been adjusted in any way to accommodate the EM-profile wheels. I can run P4 rolling stock on my layout, and I still have some vehicles which have P4 wheelsets, but I am currently working my way through them substituting EM wheels set to P4 back-to-back gauge, just to get that little bit of extra reliability that the deeper flanges of EM wheels give you. (They are only 0.25mm = .010 ins deeper, but it seems to make all the difference.)


You mention that the only difference is the flange depth. Does this mean that all of your wheels are replacement EM wheelsets, from Alan Gibson, Exactoscale and the other usual suspects?

That would make a big difference to how they go through flangeways as it would already be finescale flanges compared to OO dimensioned ones. The point that I'm making is that in effect you are approaching EM from the finescale end, rather than the approach that can be done with EM of pulling the OO wheelsets out to the EM B2B. Of course, I still don't believe that the EM profile would deal well with prototypically inset or tram (I'm typing this from Amsterdam, so I have plenty of examples outsode of just how shallow the rail grooves are) track, but that is probably not on your layout.

If you're using finescale EM wheelsets, do you know how the tyre width differs, if at all, from the P4 Standard?

martin goodall wrote:As regards a name for this 'bastard' standard, I thought of EMF, but that has been used before and meant something else, so I call it "Coarse-scale P4"! It is P4, because the track, as I have said, is exactly to P4 standards; it is just the wheel profile that's different.


I'm not sure that the name conveys exactly what you mean, because P4 describes the (rail+wheel) package as a whole but I see where you are coming from. A similar sort of thing to the seven-millers that have Coarse and Fine versions of "O", leaving aside the ScaleSeven fraternity as well.

martin goodall wrote:Where the use of EM-profile wheels really comes into its own is in converting RTR rolling stock to run on P4 track. Its quick, it's easy and it works. That, of course, is where we came in - in suggesting answers to the query posed by Julian Roberts. I can't help feeling that some of the other solutions that have been suggested are consderably more time-consuming and certianly a lot less easy than mine, even though they may be intellectually more satisfying.


I think that what you have given is a very different answer to the same question. It isn't just the intellectual satisfaction, or the complexity involved. It is that in simple terms, one is P4 and one isn't ;-)

Yours is a pragmatic solution for your own needs. It's not a quick solution to a P4 RTR conversion, but an alternative approach using 18.83 track. It gives a different result - and that's not said as criticism, by the way. If it works for you, it's a GoodThing(tm).

One aspect of your approach is that it is backwardly compatible. If a friend brings round P4 stock to run on your layout, it would work just as well as on his or her own. If you take your EM-wheeled stock to a P4 layout, it *should* run equally well but it's only your loss if it doesn't, if you see what I mean.

The problem would be if the more lax tolerances built into your EM wheels led to lower standards of track-building that then fell away from the P4 track standards, and consequently stock with P4 wheels wouldn't run on it. I could see this becoming a downward spiral that would (in all frankness) not benefit P4 modelling by having the name associated with it. But the Scalefour Society is only the guardian of the P4 standards. It doesn't own a patent on the specifications, and I don't think that it would want to, given the nastiness that apparently led to thirty years ago!

Yours is an interesting development and, as I said at the outset, not one that I would want to follow personally. But the primary objective of the Scalefour Society is to "promote finescale 4mm railway modelling" and that does not explicity exclude EMF, EM, OO or whatever. To misquote Voltaire, "I disapprove of what you model, but I will defend to the death your right to model it. " ;-)

All the best,
Flymo
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Re: Wagon Suspension

Postby martin goodall » Tue Jan 19, 2010 3:45 pm

In answer to ‘Flymo’, I confirm that all of my wheels are replacement EM wheelsets, in practice from Kean-Maygib (the steel ones – excellent) or from Alan Gibson (8-spoke and split-spoke).

Flange depth (0.25mm deeper) is not the only difference; the flange width at the flange root is also wider (by 0.1mm i.e. 0.5mm for EM compared with 0.4mm for P4), which is well within the flangeway clearance of track built to P4 standards. (I will return to that point below – there is a reason for that.)

These are ‘fine-scale’ flanges. I understand that the ‘finescale’ 00 wheels supplied by Alan Gibson are exactly the same – the only difference is the back-to-back setting. There is certainly no question of getting coarser-scale flanges to go through P4 crossings. In the early days, EM gauge was just 00 gauge with the rails and wheels pulled out to the wider gauge, but those days are long gone.

I have inset track on my layout (in the back road of the goods yard) and confirm that EM-profile wheels run perfectly there. If you think about it, there is no reason why they shouldn’t. They are set to the same back-to-back dimension as P4 wheels, so if the inset track has flangeways set to the standard P4 dimension, any wheel with the right back-to-back setting will happily run over this inset track.

As I mentioned in an earlier posting, the EM-profile wheels I use are 2.25mm wide, compared with 2mm for P4 wheels. That is an extra 10-thou on the outside of each wheel, giving an overall width over the outsides of the wheels of 22.2mm compared with 21.7mm for P4 wheels (an extra half-millimetre overall).

As to the name for my ‘bastard’ standard, frankly “Coarse-scale P4” is just a joke. You may have gathered by now that I don’t take these things too seriously. As to P4 being a single rail+wheel package, see below.

I confirm that P4 rolling stock runs perfectly happily on my layout. Equally, I am confident that my stock (fitted with EM-profile wheels) would run happily on any other layout accurately built to P4 track standards (provided that none of the track is actually less than 18.83mm gauge). On the other hand, I would not expect my stock to run on a layout built to “Scale Four” standards (again, see below).

I would like to think that my pragmatic solution might prove helpful to quite a few other people. If it works for me, there is no reason why it shouldn’t work for them too. But, of course, it is entirely a matter of personal choice, and if others prefer not to stray down this path, then they are perfectly entitled to stick to the orthodox standards which have been laid down for P4.

I think there might be some grounds for concern if I started mucking about more fundamentally with the track and wheel standards in 18.83mm gauge, but I have stuck faithfully to the P4 track standards, and would not wish to depart from them. All I have done is to use a wheel profile which in my humble opinion works more reliably on P4 track than ‘P4’ wheels do.

Let us not delude ourselves, Gentlemen. The plain fact is that there has always been a potential problem in using P4 wheels. The very fine flanges are unforgiving of even quite minute variations in rail alignment; hence the perceived need for compensated suspension or sprung suspension . At the very least (in the absence of compensation or springing) there needs to be some slop in the axle bearings to allow the wheels to accommodate themselves to minor variations in rail level.

Until P4 came along, nobody (or hardly anybody) found it necessary to mess about with fancy suspension systems. Rigidly mounted wheelsets had always been fine in 00 and EM, and even with the finer standards used in EM nowadays (compared with, say, 30+ years ago), most modellers in that gauge still do not bother to compensate or spring their rolling stock, although it is always an option in any scale or gauge, and there are certain advantages that may be claimed for it, if you are prepared to incur the extra time and trouble in adapting rolling stock to accommodate compensated suspension or springing.

Even with compensated suspension or springing, P4 rolling stock cannot be absolutely relied upon to run faultlessly. There are occasional, often inexplicable, derailments on even the best-engineered layouts. At Scaleforum last year, I saw at least one derailment (and in some cases several) on every layout I looked at. They were all built to a high standard, and the derailments represented a tiny interruption in the otherwise smooth operation of those layouts. Nevertheless, they did happen. There is always that slight chance of derailments when using P4 wheels.

This was what set me thinking about the flange profile, and led me to revisit the published track and wheel standards for both P4 and EM. When I looked these up, it immediately occurred to me that the standard EM wheel flange (as used nowadays – not the old BRMSB standard) should in principle run through the crossing flangeways and check rails of track laid to P4 standards, if the back-to-back was opened up to the P4 back-to-back gauge. Experiment proved that this is indeed the case.

As I have mentioned before, what really clinched my decision to use EM-profile wheels was the desire to convert some RTR stock to run on P4 track with the minimum of time and effort. With axles held rigidly in the plastic bearings, it would really be asking an awful lot of P4 wheels to stay on the track (notwithstanding protestations to the contrary). Some slop in the bearings is the minimum requirement if compensated suspension is not to be fitted. If building a wagon kit without compensated suspension, I ensure that there is enough sideplay for the axles inside the top-hat pin-point bearings to ensure that the axle can slop about a bit – admittedly crude, but effective as an alternative to compensation. But this is not practicable when converting RTR stock, and so the axles will inevitably be held rigidly in their bearings. Fitting EM wheels re-gauged to P4 back-to-back overcomes the track-holding problem in these circumstances.

Incidentally, I don’t know how the idea arises that providing clearance for re-gauged EM wheels involves a lot more time and effort than it does for P4 wheelsets. I am not sure exactly how many additional strokes of the file it takes to remove an extra 10-thou of plastic from the inside of each bogie sideframe or from the inside of each solebar/W-iron moulding, but it can only be a few.

Oh, one other thing. The P4 wheel standards don’t actually match the P4 track standards. The wheel profile is close-to-scale, but the track standards are a deliberate compromise, which leaves an over-scale clearance through flangeways. That is why EM-profile wheels can be run on P4 track. In fact, they are a better match for P4 track than P4 wheels. If you really wanted to use matching wheel and track standards in 18.83mm gauge, you would have to adopt the “Scale Four” standards developed by Ray Hammond, and adjust the back-to-back gauge of your wheels accordingly. (EM-profile wheels would certainly not run on track built to those standards.) If you stick to the orthodox P4 standards, then you are using a hybrid set of standards. Using EM-profile wheels in these circumstances is no more incorrect from the point of view of scale accuracy than using P4 wheels.

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LesGros
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Re: Wagon Suspension

Postby LesGros » Tue Jan 19, 2010 6:13 pm

Oh, one other thing. The P4 wheel standards don’t actually match the P4 track standards. ....

.....If you stick to the orthodox P4 standards, then you are using a hybrid set of standards. Using EM-profile wheels in these circumstances is no more incorrect from the point of view of scale accuracy than using P4 wheels.
[/quote]

SO... Experts... What SHOULD the beginners to P4 make of all of this? ...In particular, the counter claims about standards?



regards
LesG

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never made anything useful

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Mark Tatlow
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Re: Wagon Suspension

Postby Mark Tatlow » Tue Jan 19, 2010 6:48 pm

Les,

The important thing is that the full standards match each other.

Martin's comment that you have quoted is that when the original P4 standards were made, there was a comprimise made on the rail head. Actually, when you scrutinise the history of the "real railway's" standards, there will have been a whole development of these over the years and the different railway companies. It would have only been quite late on that a defined national standard was made. Thus, seeking to say that one particular profile is historically correct and all others not is not a black and white answer.

The P4 standards are, however conceived as one and do work together. As the jigs are all available and the standards are tested, you need to be confident of what you are doing and the proper relationship between the different elements before you make any real variences from them. This is largely because you need to be clear on where (or rather in which direction) you have a little tolerence and where you don't - the gauges eliminate the need for this as if you build track/stock to them it is dealt with for you.

Having said that, I can see what Martin is saying. In essence, he is saying that you can use very slightly deeper flanges that finescale EM wheels give you (and this will give you advantages) so long as your track is absolutely to gauge or very slightly over gauge and the checkrail gauge is not too big. He and I discussed this at Scaleforum and I did give it a try. I can tell you it did work right up to the point where the wheelset fouled with a check rail - this was not the fault of Martin's philosophy, as I found that the checkrail gauge was slightly tight even though a P4 wheelset will generall run through it but just occassionally not.

Actually this throws up an interesting point (which has been said before, I don't own it!). Making a wagon with wheels very slightly under guage and very slightly over gauge will be a useful tool in discovering those little errors that do creap into our work. The Society are about to launch a gravity back to back guage (see the Scalefour News from about October for Tony Sisson's articel on this). It will be very easy to set a just over and just under demo wagon from this point.



Mark
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Tim V
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Re: Wagon Suspension

Postby Tim V » Tue Jan 19, 2010 6:53 pm

Unfortunately my experience is that most running problems can be laid at the door of poor wheels. Check all wheelsets for truth, chuck out any that deviate. I have to say that the best wheels I've found are the Branchlines all nickel ones, followed by Maygib all metal, the rest I won't comment on.

Regrettably the best wheels are all discs, so fine for more modern stock. I can put these P4 wheels into RTR wagons, and they'll run, even for some modest shunting (up to half a dozen wagons).
Tim V

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jim s-w
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Re: Wagon Suspension

Postby jim s-w » Tue Jan 19, 2010 7:23 pm

martin goodall wrote:
Even with compensated suspension or springing, P4 rolling stock cannot be absolutely relied upon to run faultlessly. There are occasional, often inexplicable, derailments on even the best-engineered layouts. At Scaleforum last year, I saw at least one derailment (and in some cases several) on every layout I looked at. They were all built to a high standard, and the derailments represented a tiny interruption in the otherwise smooth operation of those layouts. Nevertheless, they did happen. There is always that slight chance of derailments when using P4 wheels.


Hi Martin

Are you claiming that by using EM wheels you get 100% faultless running? Thats some claim to make. Having taken a large EM layout out on the road for years we never got 100% reliability. I notice how you have combined what you see as the best of 2 standards P4 for track and EM for wheels but maintain that it is P4? Of course anyone else is perfectly entitled to claim that its EM thus I think the general confusion you are creating.

Incidentally, I don’t know how the idea arises that providing clearance for re-gauged EM wheels involves a lot more time and effort than it does for P4 wheelsets. I am not sure exactly how many additional strokes of the file it takes to remove an extra 10-thou of plastic from the inside of each bogie sideframe or from the inside of each solebar/W-iron moulding, but it can only be a few.


The 'idea' comes from practical experience. A p4 wheel will fit in most OO rtr wagons without need for a file. Perhaps modern wagons are different but in my real world experience EM wheels set to P4 gauge dont. The 10 thou difference you mention may not seem much in that its only 10 thou but in reality its the difference between leaving the wagon running gear completely untouched and attacking it with a big file. Try filing the back of a W iron on a RTR wagon that has clasp brakes and its a serious amount of hassle let alone a high risk of damaging the wagons detail.


Oh, one other thing. The P4 wheel standards don’t actually match the P4 track standards. The wheel profile is close-to-scale, but the track standards are a deliberate compromise, which leaves an over-scale clearance through flangeways. That is why EM-profile wheels can be run on P4 track. In fact, they are a better match for P4 track than P4 wheels. If you really wanted to use matching wheel and track standards in 18.83mm gauge, you would have to adopt the “Scale Four” standards developed by Ray Hammond, and adjust the back-to-back gauge of your wheels accordingly. (EM-profile wheels would certainly not run on track built to those standards.) If you stick to the orthodox P4 standards, then you are using a hybrid set of standards. Using EM-profile wheels in these circumstances is no more incorrect from the point of view of scale accuracy than using P4 wheels.


P4 standards are what they are. Of course they match themselves they have too! Its like saying my right hand doesnt match my right hand. Where you misunderstand is to link the P4 standard with dead scale. It isn't and has never been claimed to be. The point is in any standard all elements have to be followed. If you are using a wheel that is wider than a P4 wheel and has a deeper flange then of course it is more incorrect in terms of accuracy. Its 12.5% more wrong. You cant possibly argue that it isnt. You surely dont model everything else to a accuracy of +-12.5% do you?

As an aside (which is actually what Martins points are) I wholeheartedly agree with Tim. If your wheels are wobbly or out of round to begin with then you are in for trouble.

Cheers

Jim

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Re: Wagon Suspension

Postby martin goodall » Tue Jan 19, 2010 10:39 pm

If I can pick up a couple of points from Mark:

The important thing is that the full standards match each other.”

Unfortunately they don’t. To quote Ray Hammond (writing on the subject in 1976) “When the Protofour standards were published in 1966/7, it was readily apparent that there were two notable divergencies from exactly scaled down dimensions; namely a reduction of the wheel back-to-back dimensions from 17.87mm to 17.67mm and the correspondingly necessary opening out of flangeways and checkways from 0.58mm to 0.68mm (the recommended dimension), a discrepancy slightly in excess of 17%. ...............The objectives were (a) to make allowances for manufacturing tolerances and (b) to allow rigid wheelbase vehicles to negotiate appreciably sharper curves than the prototype.”

Ray continued: “It immediately became obvious [from his early experiences in working in P4] that there can be highly undesirable results of using exactly scaled down wheel profiles whilst other dimensions are amended, as set out above. ..........The undesirables arise from the excessive sideplay between P4 wheels and track, which in turn considerably increases the risk of buffer-locking, and sometimes causes rather peculiar behaviour on the outside road of a curved turnout.”

In the article from which I have quoted, Ray went on to describe other problems which arose due to the mismatch of P4 wheel and track standards. His answer (a perfectly valid and wholly successful one) was to tighten up the track standards and widen the back-to-gauge of the wheels to match – hence “Scale Four”. I happen to have taken the opposite course, keeping the P4 track standards, but using a wheel profile which is more compatible with the P4 track standards.

The problem, I repeat, is that the P4 wheel standards do not match the P4 track standards and never have done.

The P4 standards are, however conceived as one and do work together.”

Well, as Ray Hammond pointed out more than 30 years ago, and as I have more recently discovered, they don’t work together all that well; hence the fact that some of us have been casting about for different ways around the problem.

I can see what Martin is saying. In essence, he is saying that you can use very slightly deeper flanges that finescale EM wheels give you (and this will give you advantages) so long as your track is absolutely to gauge or very slightly over gauge and the checkrail gauge is not too big.”

The gauge of your P4 track should be not less than 18.83mm anywhere on the layout. The under-scale back-to-back of P4 wheelsets often disguises the fact that your track may be a shade under-gauge in places (even if you have used the track gauges with punctilious care). EM-profile wheels, or wheels set to “Scale Four” back-to-back (which, quite by coincidence, give exactly the same reduced running clearance between the outside of the flange and the rail-head), will soon tell you where your track is under-gauge! But the best way of checking is to use a roller gauge.

I did give it a try. I can tell you it did work right up to the point where the wheelset fouled with a check rail - this was not the fault of Martin's philosophy, as I found that the checkrail gauge was slightly tight even though a P4 wheelset will generally run through it but just occasionally not."

I have encountered no such problem. It is an essential pre-requisite to the successful use of EM-profile wheels set to the P4 back-to-back gauge that your track is actually laid accurately to the P4 settings. Check rails must be correctly gauged and crossing flangeways must be the right width. It is ironic that most people get away with less than accurate track in P4 simply because of the mis-match between the track and wheel standards, which provides an over-generous tolerance between wheels and rails. But as Ray Hammond pointed out in the article from which I quoted above, that also has its downside.

Tim Venton wrote; “Unfortunately my experience is that most running problems can be laid at the door of poor wheels. Check all wheelsets for truth, chuck out any that deviate. I have to say that the best wheels I've found are the Branchlines all nickel ones, followed by Maygib all metal, the rest I won't comment on.”

Yes. Absolutely. Ultrascale, Maygib and Branchlines (P4 only; their others are RP25 – which won’t run on P4 track) are very good. Others have to be very carefully checked.

Next, Jim : “Are you claiming that by using EM wheels you get 100% faultless running?”

Yup; that’s what I’m saying. I reckon you can get 95% reliability with P4 wheels (maybe a little more), but 100% with EM-profile wheels, always provided you have set the back-to-back correctly, and your track does conform exactly to P4 standards.

Having taken a large EM layout out on the road for years we never got 100% reliability

Because, there is a similar mis-match between the EM back-to-back gauge and the EM track gauge – the running clearance is far too big, giving exactly the same problems as Ray Hammond identified with P4. If you were to tighten up the EM flangeways and check rail clearances to the P4 dimensions, you would get exactly the same results as I get using EM-profile wheels on P4 track.

I notice how you have combined what you see as the best of two standards - P4 for track and EM for wheels but maintain that it is P4? Of course anyone else is perfectly entitled to claim that its EM thus I think the general confusion you are creating.”

I can’t see any way of avoiding that. The track is P4, and the wheels are set to P4 back-to-back, so on balance, I would still say it is 'P4'. But the confusion really stems from the incompatibility between the very accurate P4 wheel profile and the rather less accurate P4 back-to-back setting combined with over-generous P4 flangeway/checkrail clearances. Ray Hammond’s “Scale Four” and my “Coarse-scale P4” are different ways of tackling the same problem. I happen to prefer my solution, because it also gives the added advantage of a deeper wheel flange, which was the main consideration so far as I was concerned.

If you are using a wheel that is wider than a P4 wheel and has a deeper flange then of course it is more incorrect in terms of accuracy. It’s 12.5% more wrong.”

Whereas, as Ray Hammond pointed out, the P4 back-to-back gauge involves a discrepancy slightly in excess of 17%! ( - a case of stones and glass houses, perhaps? Or pots and kettles?)

ClikC

Re: Wagon Suspension

Postby ClikC » Tue Jan 19, 2010 11:04 pm

As a new comer to P4, part of the draw to P4 standards was modeling the railway as a mechanical system in whole. For the most part I'm fasinated by how the real railway works, and reading through the digest sheets as part of my members pack has taught me a lot about how the railway works. It's this I'd like to emulate, It's the engineering side of P4 that appeals to me, even if it means some extra trouble to produce a single item of stock.

Regards

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jim s-w
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Re: Wagon Suspension

Postby jim s-w » Wed Jan 20, 2010 8:28 am

martin goodall wrote:Next, Jim : “Are you claiming that by using EM wheels you get 100% faultless running?”

Yup; that’s what I’m saying. I reckon you can get 95% reliability with P4 wheels (maybe a little more), but 100% with EM-profile wheels, always provided you have set the back-to-back correctly, and your track does conform exactly to P4 standards.


This I gotta see. When are you next showing your layout? I havent seen the article you refer too (its nearly 10 years older than I am!) however you are still confusing the P4 standard with dead scale.

If you are using a wheel that is wider than a P4 wheel and has a deeper flange then of course it is more incorrect in terms of accuracy. It’s 12.5% more wrong.”

Whereas, as Ray Hammond pointed out, the P4 back-to-back gauge involves a discrepancy slightly in excess of 17%! ( - a case of stones and glass houses, perhaps? Or pots and kettles?)


Not at all - I did say what you are claiming is the same is 12.5% MORE wrong. I am ducking out of this one as you clearly have completely missed the point of P4. I am glad your system works for you but I have never been one to take the 'it'll do' path and I still warn (from practical experience) that its can be more hassle than using p4 wheels. Its a decent enough bodge but only as an absolute last resort.

Cheers

Jim
Last edited by jim s-w on Wed Jan 20, 2010 12:03 pm, edited 1 time in total.

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Will L
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Re: Wagon Suspension

Postby Will L » Wed Jan 20, 2010 9:11 am

jim s-w wrote:
martin goodall wrote:Next, Jim : “Are you claiming that by using EM wheels you get 100% faultless running?”

Yup; that’s what I’m saying. I reckon you can get 95% reliability with P4 wheels (maybe a little more), but 100% with EM-profile wheels, always provided you have set the back-to-back correctly, and your track does conform exactly to P4 standards.


This I gotta see.


Will Litchfield like this comment. Wops sorry this isn't Facebook is it.

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iak
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Re: Wagon Suspension

Postby iak » Wed Jan 20, 2010 10:01 am

Ladies & Gentleman...
This case will be be heard at the Auld Bailey in June Image
Back to backs, intrigue and soldering irons - love it...
I don't suffer from insanity, I enjoy every minute of it....

Perfection is impossible.
But I may choose to serve perfection....
Robert Fripp


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Flymo748
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Re: Wagon Suspension

Postby Flymo748 » Wed Jan 20, 2010 10:47 pm

Will L wrote:Will Litchfield like this comment. Wops sorry this isn't Facebook is it.


Paul Willis: added you as a friend on Facebook. We need to confirm that you know Paul in order for you to be friends on Facebook. ;-)

Flymo
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martin goodall
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Re: Wagon Suspension

Postby martin goodall » Thu Jan 21, 2010 2:35 pm

Unfortunately, the Burford Branch is not portable and not therefore exhibitable. I hope to be able to show it to friends who are interested later this year when I have done a bit more scenic work on the layout. (I gather the layout has now appeared in MRJ No.196, but my copy has not yet come to hand.)

My other layout, Crichel Down, is currently moth-balled and I am not sure when (or whether) it might return to the exhibition circuit. All the stock on that layout still has P4 wheels and has not yet been fitted with EM-profile wheels.

It is tempting to build an exhibiton layout with P4 track, but equipped exclusively with rolling stock fitted with EM-profile wheels just to demonstrate the point (maybe Crichel Down (Mark II)?), but I have no idea how I would ever find the time to do so.

Meanwhile I am very happy with the running on the Burford Branch . The only (admittedly rare) derailments that occur are with those vehicles still fitted with P4 wheels.

I can only suggest that anyone who would like to see if it really does work might try converting one or two vehicles for themselves. There's no need to commit yourself to a wholesale conversion programme. Just see how the converted vehicles behave. If they bump or jump anywhere on the track, it will be because the track gauge at that point is marginally less than 18.83mm and should be adjusted.

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Re: Wagon Suspension

Postby HowardGWR » Fri Jan 22, 2010 3:12 pm

Martin's articles in MRJ (see <http://www.modelrailwayjournal.com/index.php> and search with 'Marin Goodall' and 'authors') were a treat. I particularly enjoyed his Heckmondwike anecdote with the wagons with sloppy fitting axles 'sailing through' the switches in reverse while the P4 engine pushing them derailed. Mind you. I think he was using P4 wheels for that exercise or perhaps he perpetrated a gigantic con on everyone and they did not notice ;)

I kept all my EM wheels and use both. Small experimentation on my cattle wagons that were not particularly heavily weighted did not reveal any noticeable differences in riding, mind you, and I did follow the 'sloppy' method that Martin describes. I've still a lot to learn to be honest (have entered the armchair modeller competition - nervous laugh follows).
Many thanks for this forum Keith.

Regards, Howard

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Re: Wagon Suspension

Postby martin goodall » Fri Jan 22, 2010 3:39 pm

In those days I only ever used P4 wheels. It never occurred to me at that time that you could run EM-profile wheels through P4 crossings, and that in fact they actually run better on P4 track than P4 wheels do.

Bearing in mind the exchanges on this topic over the past few days, I laughed out loud when I saw MRJ No.196, which bills the Burford Branch as an EM Gauge layout. Maybe my interlocutors think it should be!

I confess that I really can't take any of this very seriously. I just do model-making for the fun of it, which I suppose is why I have such a cavalier attitude towards scale accuracy. I just don't buy the 'perfection on wheels' approach, especially when it deliberately overlooks the obvious inaccuracies in the P4 standards themselves.

In view of those inaccuracies in the P4 wheel and track standards, I think the Society ought possibly to change its motto to "Getting it nearly right (but not quite)". I would still support a society with that philosophy.

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David Thorpe
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Re: Wagon Suspension

Postby David Thorpe » Fri Jan 22, 2010 6:44 pm

A little off topic ("Wagon" suspension), but I assume that while rolling stock with EM profile wheels runs on P4 track, the same cannot be said of locos?

David

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LesGros
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Re: Wagon Suspension

Postby LesGros » Fri Jan 22, 2010 7:07 pm

Martin,
This thread has wandered way off topic into an area of a discussion that is more about society policy:

Enjoy your Modelling.
Last edited by LesGros on Sun Jan 24, 2010 7:32 am, edited 1 time in total.
LesG

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never made anything useful

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Jim Summers
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Re: Wagon Suspension

Postby Jim Summers » Fri Jan 22, 2010 10:13 pm

The Society's Chairman's wee brain is beginning to hurt.

At lunchtime he read the latest MRJ, which states Martin's layout is EM (and a very nice article it is too). He then managed to get a measurement wrong on a scratchbuilt engine he was working on this evening, so that the the cab footplate is wider than the P4 back-to-back between the splashers in the cab - not good. Then he switched on the computer and caught up with all this glorious wheel activity about EM/P4/S4 and the One True Path or not.
And then he lifted his eyes to the two Bavarian RTR HO locos on the shelf and the scratchbuilt Bavarian 2-4-4T he built thirty years ago, and suddenly HO and RTR appealed all over again.

I suppose the point is that there are all sorts of ways of having fun in what we do. I am rather pleased that in this society some of us can take a purist engineering view (and presumably don't have to rebuild wrong footplates), and others can take a more pragmatic approach and can still sleep at night. So long as we all know that there are published P4 standards, which folk worked hard to establish in the past, then if Martin wants to experiment with them and share his results, that is fine. And if others want to know more or challenge him then that is fine too.

It would be a poor society if we couldn't enjoy a debate. And even on the prototype railway there is a process to challenge standards and seek changes.

But I am beginning to think this particular debate shows signs of distracting us from getting on with the modelling and risks depressing newer members, and maybe we should let it rest for a while. The good thing is that Martin and the other contributors are sure guaranteed big audiences when they present their layouts.

Jim

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Andy C
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Re: Wagon Suspension

Postby Andy C » Fri Jan 22, 2010 11:11 pm

Caleyman wrote:
It would be a poor society if we couldn't enjoy a debate. And even on the prototype railway there is a process to challenge standards and seek changes.

But I am beginning to think this particular debate shows signs of distracting us from getting on with the modelling and risks depressing newer members, and maybe we should let it rest for a while. The good thing is that Martin and the other contributors are sure guaranteed big audiences when they present their layouts.

Jim



Ahhh a breath of fresh air and common sense. Well said Jim
Last edited by Andy C on Sat Jan 23, 2010 10:05 pm, edited 1 time in total.

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Captain Kernow
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Re: Wagon Suspension

Postby Captain Kernow » Sat Jan 23, 2010 8:48 pm

Andy C wrote:Ahhh a breath of fresh air and common sense. Well said Jim

Hear hear!

And I take my hat off to Martin for what I think is a pretty courageous stance to take on the Society forum!

I don't know whether I'll end up deviating from installing compensation and suspension systems to my P4 rolling stock, but I certainly never realised that EM wheelsets would work on P4 track.

For me, reliable running comes higher up my priority list than worrying about whether the wheels are 100% right or not - clearly someone viewing your layout at normal viewing distances may not spot the EM wheelsets, but they'll certainly notice a wagon that derails. So, it it works for Martin, then why not?

I'm also aware that Martin isn't the only person working to 'P' standards but is prepared to adopt flange or wheeltread 'ruses' to improve road-holding....

Finally, I would like to thank Martin for a super article in MRJ 196 and also for enlightening me that it's not necessary for me to wear my hair shirt every day!... ;) ;)
Last edited by Captain Kernow on Sat Jan 23, 2010 8:58 pm, edited 1 time in total.
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Re: Wagon Suspension

Postby grovenor-2685 » Sat Jan 23, 2010 8:56 pm

People,
It really is not necessary to quote the Chairman's entire message to add a hear hear or another couple of lines, the original message is still there to be read, please be selective in your quotations if you need to quote at all. There is no need to quote when making a general reply to the message immediately above.
Thanks
Keith


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