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topic: 2515Wheelset sideways slop between rails
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posted: 20 Aug 2014 10:45

from:

Brian McK
 
 

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Greetings all,

I'm modelling New Zealand's 3' 6" gauge system circa 1920s to 1:48 scale.  While I can produce my own wheels and trackwork scaled exactly true from the prototype, do recognise that a very slight increase of the 1-3/4 inch wide turnout flangeways with a commensurate adjustment to wheelset B to B may be a more realistic goal for construction and operational reliability.

However, my question is this.  In trying to ascertain dimensions for assembled wheelsets, what amount of "sideways slop" is appropriate for wheelsets in my scale on 22.2mm gauge?  I'm aware that a tightening of track gauge has improved matters for O scalers (O-MF etc) and that a similar practice is occuring in 4mm scale, thus removing some of the clearance allowed for "trainset" wheels to run around curvature of dinner plate radius.

I could study P4 and S7 etc and perhaps formulate something from that.  But maybe there is a model formula (?) - and the thoughts and experiences of others would be valued.  Wheel profile has the typical prototype fillet to the flange, rail is mostly code 100 with a minimum radius of about 6ft.  Gauge widening on curves if necessary and through curved portions of turnouts.

Thanks and regards,
Brian McKenzie

posted: 20 Aug 2014 22:55

from:

Matt M.
 
Australia

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Hi Brian,

If you can produce your own wheels and track work, check the Proto 48
website to see if their standards meet the criteria that you are looking for.
http://www.proto48.org

Regards, Matt M.

posted: 21 Aug 2014 00:31

from:

Brian McK
 
 

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Thanks Matt.  I first produced a batch of wagon tyres to those specs, only to find that North American prototype standards for standard gauge are quite different to those for narrow gauge systems such as in New Zealand and indeed for America's Colorado narrow gauge, which causes issues for some of the On3 fraternity constructing mixed gauge track.

Flanges on American railroad wheels are wider and perhaps marginally shallower than for our 3' 6" system.  The really noticeable difference is that their flangeways are up to 2-1/2" wide, whereas my prototype is at 1-3/4", significantly smaller in percentage terms.

I'm keen to retain the narrow gutted look of our skinny flangeways as much as possible, but are prepared to ease these marginally in the interests of practicality.

When I first started on this path a few years ago, Keith Norwood kindly provided diagrams of South African Rlys 3' 6" standards.  However, standards used by the beefier SAR are more akin to those for standard gauge systems.  When several SAR steam locos were imported to NZ by enthusiasts, tyres were required to be re-profiled before they were permitted to move through turnouts. 

I never imagined there could be so much difference between rail systems.

Returning to my original question, that of appropriate clearance between rail and wheel flange - "or sideways slop" for model wheelsets that traverse tighter than prototypical curvature.  I could scale directly from the prototype, and then reduce back to back and checkgauge in unison marginally, which would likely achieve the slight concession I'm alluding to.

-Brian McKenzie


Matt M. wrote:
If you can produce your own wheels and track work, check the Proto 48
website to see if their standards meet the criteria that you are looking for.
http://www.proto48.org


posted: 21 Aug 2014 01:01

from:

Matt M.
 
Australia

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Hi Brian,

Even on the same system you end up with continuous development.

As I am interested in pre-1930's New South Wales I've been going down
the research path for a few years.

I now have the information to reproduce track standards from the 1890's
to 1970's. But the amount of information and how to use it correctly
is daunting. Between the 1890's and 1932 they already had 5 different
methods of constructing the crossing in a lead formation.
2 different methods of attaching wing rails and 8 different styles
of plate type.

On your problem re clearances between rail and wheel I know of a friend
of a friend who has for years done his own thing as a version of P87.
He copies prototype and has no problems. Indeed his layout operates
impeccably by all accounts. I'll pass on your query regarding clearance
issues and will get back to you when I get a reply.

NSW O is 7mm. I went S7 for similar reasons. Still a compromise.

Regard, Matt M.

posted: 21 Aug 2014 08:59

from:

Alan Turner
 
Dudley - United Kingdom

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Brian McK wrote:
Thanks Matt. 

Flanges on American railroad wheels are wider and perhaps marginally shallower than for our 3' 6" system.  The really noticeable difference is that their flangeways are up to 2-1/2" wide, whereas my prototype is at 1-3/4", significantly smaller in percentage terms.


-Brian McKenzie


 

I can't answer for American Railways but the 1-3/4" flangway dimension is standard to British crossings. By all means use 1:48 but if you were to use 1:43.5 (7mm to 1') then Scale 7 standards would be appropriate adjusted for track gauge.

You could of course use 43.5/48 of Scale 7 standards (taking appropriate note of track gauge)

regards

Alan
Last edited on 21 Aug 2014 09:03 by Alan Turner
posted: 21 Aug 2014 09:26

from:

Matt M.
 
Australia

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Alan,

Due to our English heritage it's the same in New South Wales and
New Zealand.
Hence S7 works for me. So the back to back tolerances should be
very close for Brian.

However there is some debate here regarding using P4 standards
for P87 as they don't quite work. The gentleman I refer to is an
engineer and has built to a set of scale prototype standards
And it works.

I may have to wait a few days or so for an answer.

Regards, Matt M.

posted: 21 Aug 2014 10:45

from:

Brian McK
 
 

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Alan, Matt

Having just got back into my project (now retired) I hadn't yet noticed that British crossings are 1-3/4" wide so the suggestion of adapting or re-scaling Scale7 standards to 1:48 is really useful advice.

The notion of the tiniest easing of flangeways etc is primarily for the benefit of other colleagues who might struggle to meet and maintain such strict standards.

To re-format my original question: What would the British fullsize track standard be if the prototype had to contend with the curvature as we use in our model railways?

Thanks,
Brian McKenzie

posted: 21 Aug 2014 10:54

from:

Brian McK
 
 

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Oops, should have written WHEEL and track standard. . .
I imagine there could be more alteration to wheels than to trackwork for the question below . . . maybe

What would the British fullsize wheel and track standard be if the prototype had to contend with the curvature as we use in our model railways?

Thanks,
Brian McKenzie

posted: 21 Aug 2014 12:26

from:

Matt M.
 
Australia

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Brian, if New Zealand is like Australia, with the railways built on the cheap
by successive governments, then a radius of 8 chains is a fairly common
occurrence on supposedly main lines. That was also the minimum radius
for all main line equipment. They had a test loop at Clyde Wagon Works
to check compliance.

In 7mm 8 chains is 3696mm or slightly over 12 foot.
So realistically there isn't a standard as such for smaller radiuses.

But as I understand it a set wheel profile and back to back is necessary
regardless of what standard you settle on.

I'm not sure who else you are worried about run stock over your layout.
If you are starting from scratch to build a brand new set of standards no one is
going to be able to operate on your layout unless they meet those requirements.

There are only a few S7 modellers here. And only two others doing NSWGR.
Only one lives close to me and thankfully does pre 1900. So not many to run
their stock on the track when finished.

Regards, Matt M.

PS. I have passed on your query.

posted: 21 Aug 2014 13:51

from:

Phil O
 
Plymouth - United Kingdom

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The use of gauge widening takes care of any additional wiggle room required for long wheelbase rolling stock as per prototype. This is acheived when modelling by using a three point gauge.

There is at least one exhibition layout with three foot radius track built to P4/S4 standards.

Phil.

posted: 21 Aug 2014 23:40

from:

Brian McK
 
 

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I think Russ Elliott's explanation at

http://www.clag.org.uk/p4standards.html

of how the P4 standard has evolved should answer my question re sideplay in wheelsets.

     "The clearance . . . .  represents the sideplay of the wheelset on the
     track gauge.  In the formulation of P4 standards, a nominal clearance
     value of 0.25mm was adopted, in order to take account of the less than
     prototype equivalent track radii used in models, and the accuracy to
     which the wheelset BB could reasonably be expected to be maintained
     within the specified maximum.  In practice, experience has shown that
     0.25mm may be a little too generous, and a clearance of 0.15mm may be
     regarded as the minimum permissible."

At this early stage of my renewed study, it appears that P4 makes use of
some concessions as I have been pondering for 1:48 scale on 22.2mm gauge
track - but that Scale7 is essentially a direct scale reduction from the prototype (?)

Shall prepare comparison diagrams tonight after spending the day in the workshop.

Cheers,
Brian McKenzie

posted: 22 Aug 2014 07:33

from:

Jim Guthrie
 
United Kingdom

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Brian McK wrote:
At this early stage of my renewed study, it appears that P4 makes use of
some concessions as I have been pondering for 1:48 scale on 22.2mm gauge
track - but that Scale7 is essentially a direct scale reduction from the prototype (?)
 
Brian,

I can just about remember the Exact Standards discussions of over forty years ago - some might call them battles :) - but most scales other than 4mm decided not to accept the P4 compromises that had been re-scaled to other scales,  and Scale7 was one of them.   The P4 developers came up with recommendations for all the other scales and I don't think any were accepted.  In fact the name Scale Four was given to a set of more exact standards for 4mm scale.

However,  you may want to look at the UK S scale standards which were developed by Ian Pusey about fifty years ago and were basically the prototype standards divided by 64.

http://www.s-scale.org.uk/standards.htm

I'm not sure how they might suit your 1:48 NZ Cape Gauge models but the gauge is pretty close to your 22.2mm and the wheel and flange widths may be close to your requirement.

Jim.

posted: 24 Aug 2014 15:10

from:

Matt M.
 
Australia

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Hi Brian,

Got answer back.



"This sound disingenuous,
But it is better to ignore so-called modelling standards - especially if you have the ability to machine your own wheels.
Simply make the wheels and the track accurately to scale according to the particular full scale prototype.
That applies directly to wheel tread profile (not difficult at all in O scale) and clearances through crossings.
You can use whatever gauge widening is required to compensate for tighter than scale curvature.
He's probably correct in suggesting an allowance at curved crossings too.

The key to fault-free operation is :-
1. Scale wheel tread and back-to-back.
2. Scale clearances (check rail spacing etc) at crossings.
3. Construction gauges made accurately and used intelligently.

This avoids the need to introduce factors and corrections like P4 and P87 which
have 'added' factors which sometimes invalidate the governing inequalities.

Basically, if you have the skill / wherewithal to make your own stuff with machine tools
accurately (intuitively obvious), then you can ignore all the "modelling propaganda" about
standards, and simply make models that work properly in the first place.

Oscar did it this way and eliminated all the problems and it works perfectly !! It was deceptively simple to achieve."



I have only seen a little bit of video of Oscar's layout but I am oping for an invite at some point.
Everyone that I know who has seen it in action swears it is the best running 3.5 mm layout they have seen.

Good on Jim for thinking of S. I didn't as it isn't scale that raises it's head here.

I'm interested in hearing how it goes Brian.

Regards, Matt M.

posted: 25 Aug 2014 01:59

from:

Brian McK
 
 

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Thanks men, your suggestions are appreciated.

Yes, it is looking likely best to follow prototype dimensions without concession.  I'm equipped to do that without much pain, but had been hoping to find a path where a close or similar practice could be followed by others without too much difficulty.

Jim will be pleased that fellow modellers in NZ are experimenting with S Scale Society tyres plus the common NMRA HO scale RP25-110 profile.  Where they are starting to go off the rails is by suggesting the use of NMRA's S scale recommended track gauge of 22.4mm, to set the standard for 3' 6" gauge models at 1:48 scale (which equates to 22.23mm).  Ironically, individuals have been hand-laying track and are not likely to use any S scale proprietary track system.

While it is fine to suggest use of the above products as a quick way "in", and such flex track can be compatible, I'd prefer that a widened track gauge not be used to arrive at a new modelling standard.  This potentially creates more problems than using a narrower gauge.

In casting about looking at different products and tyre profiles, it seemed necessary to learn what clearance was actually desirable between rail and wheel flange, before getting into flange width and establishing back to back dimensions etc.

Other than the Russ Elliott comment quoted earlier, I've not yet come across other model deliberations regarding that matter.  In a practical sense, this will change wherever gauge widening comes into play.  Additional data is being sought for some tyre comparison diagrams in preparation.


Regards,
Brian McKenzie

Matt, I've given fleeting thought to visiting Sydney briefly leading to the Liverpool exhibition.  Not sure if I can manage now, but any ideas that encourage are welcome.
Last edited on 25 Aug 2014 07:00 by Brian McK
posted: 25 Aug 2014 04:52

from:

Brian McK
 
 

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414_242342_470000000.jpg414_242342_470000000.jpg
                                  3.5 mm "true" scale wheels, not P87, of NSWGRlys prototype

Matt,

Have just viewed Oscar Deluca's two videos on YouTube.
 
  http://www.youtube.com/watch?feature=player_detailpage&v=es-IAV0LjF8

  http://www.youtube.com/watch?feature=player_detailpage&v=OKcGt8CVwPA

I greatly admire the fine workmanship he has applied to the truly scaled concentric wheels - and to the matching turnout construction.  Another Brian Harrap.  Photos snipped illicitly from video.

-Brian McKenzie
Last edited on 25 Aug 2014 08:13 by Brian McK
posted: 25 Aug 2014 08:44

from:

Jim Guthrie
 
United Kingdom

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Brian McK wrote:
Jim will be pleased that fellow modellers in NZ are experimenting with S Scale Society tyres plus the common NMRA HO scale RP25-110 profile.  Where they are starting to go off the rails is by suggesting the use of NMRA's S scale recommended track gauge of 22.4mm, to set the standard for 3' 6" gauge models at 1:48 scale (which equates to 22.23mm).  Ironically, individuals have been hand-laying track and are not likely to use any S scale proprietary track system.
Brian,

Another tyre profile which might be of use is the 4mm scale Manchester profile which was drawn up many years ago by members of the Manchester Model Railway Society as a finer scale tyre for EM gauge than the BRMSB profile.  This profile was available from Mike Sharman when he was producing wheels and I believe Gibson are also providing it today - maybe Ultrascale as well.   It is "as near as dammit" :) the UK S Scale profile and a lot of us have used Sharman 4mm scale "Manchester" wheels with success on S scale track.

I suspect that the problem of using smaller scale tyre profiles for larger scale narrow gauge modelling might be that the tyre will not be wide enough - which might offend the eye,  but would give a bit more room for outside motion. :)

As an aside,  I do like the NZ option of 9mm scale on 0 scale track to represent Cape Gauge - getting nice and meaty in size. :)

Jim.

posted: 25 Aug 2014 09:26

from:

Matt M.
 
Australia

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Hi Brian,

Glad you like what you see of Oscar's work. I will pass on the compliment.

Not doing Liverpool myself this year as it is three hours of travel by car and as
a carer it is just a little difficult to organise.

Don't know if it is possible to organise to meet Oscar but I would ask if you like.

David and I don't have a layout… yet. But I'm hoping to have more than the two short
test tracks up by the end of the year. And a couple of the locos finished sans painting.

I went for S7 due to the finer wheels and ability to negotiate prototype track formations
without problems. We will probably move into making our own as early loco wheels
have a very thin rim and tyre which the Slaters wheels can't replicate.

Currently my efforts for the last two years have been researching the area we want to
model first.

And the Permanent Way.

I really want to do a decent job on the PW as generally this is still an area that is wrong
on model railways here. They don't reflect NSWGR practice or equipment.
But getting the correct information for anything of the periods I model is hard.
I'm still in the process of sorting through what I have and making notes.
Then back into Templot to work through what makes up a correct formation.

Currently also getting on top of another CAD program, this one happily seems
to work on Apple Mac without keeling over.
Then to reproduce the chairs for 70lb double headed rail (still have to select a model
rail profile to match), that was the mainstay of the NSWGR from 1857 to 1894.
And the correct switch slide chairs for the 70lb flat bottom rail that replaced it,
(accurate rail thankfully sorted by Karlgarin Models).

Lots to do.

Regards, Matt M.

posted: 25 Aug 2014 13:42

from:

Matt M.
 
Australia

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Oops.

75lb double headed rail and 71-1/2lb flat bottom.
Need more sleep.

Matt M.

posted: 27 Aug 2014 22:28

from:

Brian McK
 
 

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Jim Guthrie wrote:
Another tyre profile which might be of use is the 4mm scale Manchester profile which was drawn up many years ago by members of the Manchester Model Railway Society as a finer scale tyre. . . . . 

Jim,

Wheel-making articles in the old 'Model Railway News' authored by Sid Stubbs of the Manchester group prompted my first purchase of a lathe when still a schoolboy.  The 'Super Adept' was replaced by a Unimat SL soon after I entered the work force, and machines have got bigger ever since. 

I was privileged to spend time with Sid and Mrs Stubbs about 20 years ago.  By that time I was well immersed in engineering, having made gears and gearboxes to Sid's design (MRJ issue #42) and like Sid, designing gears in real life at that time.  He arranged the chain drive to a locomotive displayed at Manchester's Museum of Science & Industry.

His attic layout to "Manchester" standards performed superbly.  It had extensive electrical interlocking and Sid would sometimes run his locomotives at alarming speed to demonstrate the effectiveness of the fail safe circuitry!

Now having seen the video footage of Oscar Deluca's exact scale work in HO, the way forward seems quite clear, scale from prototype practice, no more no less! 


Matt,
Are you "c.......unctum" elsewhere online?  If so, I could forward items that might be of assistance to you.


Regards,
Brian McKenzie

posted: 27 Aug 2014 22:55

from:

Matt M.
 
Australia

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Hi Brian,

If you wish to email direct that would be fine.

Regards, Matt M.

posted: 27 Aug 2014 23:06

from:

Brian McK
 
 

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More of Oscar Deluca's exact scale work:

http://www.flickr.com/photos/55037064@N05/?saved=1

http://www.railpage.com.au/f-p1487569.htm

posted: 27 Aug 2014 23:19

from:

Matt M.
 
Australia

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Hi Brian,

Craig Mackey and I have a team effort going in locating and documenting
the surviving drawings and other information of the NSWGR.
He is also co-ordinating the rebuild of 3801 at the old boiler shop at Chullora.
A project that is getting in the way of his modelling.
Though I think 12" to12" scale modelling counts.

Matt M.



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