In HG's Book (1924 edition) "Model Railways" on the top of page 48 there is a paragraph on wheels. "The use of carrying wheels running loose on their axles" and a note that this was first proposed and championed several decades ago by Mr Henry Lea (M.I.C.E.). He notes that if this is correctly done that it is, "a refinement to value".
I have tried this and found it to be a great success with my rolling stock, I wrote an article about it in the IanT era for the Newsletter. I only have a small back garden and thus can only "afford" tight curves of 3m to 3.6m radius or 3.3 chains to 3.9 chains radius -this is also aided by inside curve gauge widening on all curves!!!
I take the viewpoint that IRW assists the coning by allowing the wheel to move at differing angular velocities whilst cornering at radii below that at which the coning could function effectively.
QUESTION:
Has anyone else tried this and/or what are your feeling on the matter?
regards
ralph
Ralph,
I have not tried it but with ball/roller bearing is there not a run-away problem with "parked" stock in sidings which have even the slightest (of unintentional) gradient?
I have found that GRS carriages and wagons with plain bearings roll on what is almost level track and, even on perfectly level track, a slight gust of wind can move them quite a distance.
I think I am going to have to use "Scotch blocks" in my exposed sidings.
Have you had any such problems?
Regards,
John.
John,
Yes they do roll quite easily in the breeze...
But that is rolling friction, rather than cornering ability -which is my main concern.
In an IRW system the axle does not rotate and the roller races sit in the hub of the wheel. Hopefully by the end of this year "The Shed" and "Kitchen Sink Engineering" will have produced the basics for six LMS period three suburban coaches. The idea is to minimise the cornering drag from 24 sets of axles into the more "tractable" 48 wheels moving at the correct angular velocity -rather than suffer the losses due to the continuous slide and slip of the typical railway wheel set.
The system has several advantages that I feel bear some other person giving it an independent appraisal. There have been several real world practical studies made of the system -some of which are actually written to be readable(!)
Before some suggests it -NO! I am not going to fit EFF bogies to my LMS stock, although some form of "bogie dampers" or "shimmy shocks" will be used.
regards
ralph
It is an interesting idea Ralph and was published under the title "Tight Curves" in Newsletter 77 (June 2009).
If any member who doesn't have this back-number would like to read Ralphs original article, it is available as a PDF document on the G3 Society's website - but you will need to log-in. I haven't checked but I think there was a photo or two originally - but obviously I couldn't find them when I converted this article (and about 50 others) for the G3S website a year or so ago.
Regards,
IanT
LGB produced an axle with independently rolling wheels (roller bearings and electrical pickup) I found them very useful when building a Siemens Combino tram in G scale, running on R1 (60cm) curves.
Ralph's idea of Independently Rotating Wheels, or maybe his promotion of the idea if not his own, actually has a lot of merit for the sorts of tight corners we have to endure on our layouts. I worked through some figures one lunchtime at work, based on a study of carriage sized wheels (3'6"), machined to the G3S standard profile, running on either 63.5 mm, or 64.5 mm gauge-widened track.
Now I'm not talking about wheelbase or wheel configuration, or how much side slop to engineer into the chassis, it is purely the effect of the cone angle in helping the axle around a curve.
The results surprised me.
To avoid skidding of one or other wheel on the rail, and thereby avoiding considerable friction, the standard gauge needs to be 12.5 m radius. That's over 40 feet!
Even if we gauge widen by 1 mm, the radius needs to be 9 m.
Now I'm probably not alone in thinking these lovely, gentle, sweeping curves are impractical, so the questions are:
- do we bother about it and just drag the stock around our practical curves, protesting and squealing?
- is it even worthwhile going for Gauge-widening as we are rarely, if ever, going to solve the problem by it?
- or do we adopt IRW and hope it doesn't give problems of stability on the straight?
I'd be interested to hear how well (or badly) that IRW perform on straight track, because the fundamental reason for fixed wheels with coning is to self-centre, and presumably stabilise forward motion.
That's enough deep thought for one night!
Regards, Tim
[/list]
Well Tim, I have the wagons and the drag strip. No.5 can do 50mph (scale). You have until mid September to experiment to your hearts content!!!
Regards
Ralph
Having spent 10 minutes running No.5 up and down the drag strip and the great north straight everything seems to behave normally.
Regards
Ralph
Thanks for the kind offer Ralph, which I shall take up. I should like to include a comparison of conventional stock and those with IRW, even if it's just a subjective comparison of pulling them around a curve by hand.
I shall be in touch.
Best regards, Tim
Well I have some results from pulling these around a curve on Ralph's track:
- 2 x hopper wagons with wheels mounted independently on ball races, approx 50 - 70 grammes
- 1 x bogie coach with fixed wheels on axles mounted in 4 mm plain oiled journal bearings, approx 80 - 150 grammes
Therefore approximately double the drag occurs with conventional fixed wheels, and I don't attribute all of this increase to the plain bearings. Ralph's curves aren't particularly tight, typically about 8-10 feet I think (there is a bit of a reduced radius node part-way around this particular curve), which is going to be pretty well representative of what most of us can hope to fit in the back yard, or on an indoor layout.
Ralph also assures us that stability of IRW stock on a straight is not a problem.
I can only conclude that IRW stock makes a lot of sense for us on rolling stock and unpowered loco wheels.
I shall now have to rethink all those Slater's wheels bought for my BR coaches!
Regards, Tim
Tim,
I do wonder whether too little friction is not a good thing.
Even on a moderately "breezy" day, items of rolling stock start moving under "sail power" and the GRS "B set" will start to roll on even the slightest (invisible to the naked eye) incline.
Too little friction and we shall need to install working brakes and "Scotch blocks" to prevent runaways!
Regards,
John.
John, I'm only talking about friction on curves caused by wheels scuffing as a result of the curve being too tight for the wheel coning to deal with. It's nothing to do with rolling friction on a straight track. I'm only a beginner, but I'm sensing that nobody really wants the stock to roll beautifully along the straights, but the friction to greatly increase as soon as it comes to a curve. That would be awfully difficult to deal with on a "free-flight" live steamer, and not so good on R/C battery-electric either. I used to think that friction on curves was just the occasional contact between flanges and rail, but now I've done the calcs, I know it's caused by one or other wheel on each axle having to physically slip because its contact patch is moving at a speed different to the 'rail speed'.
If you want resistance to motion, try putting a dynamo on your coaches! If some clever and realistic brakes linkages are made up from etches, rather like on Garfield Models' Midland van kit, then I'm sure a small servo and springy linkage could be concealed as a parking brake!
Regards,
Tim
Please excuse my rusty and very old "O" level physics, but isn't that why we have coning on the tread of wheels - allows one wheel to travel further than the other?
One cause of friction on curves is the angle at which many wheels will approach it, especially on a fixed wheelbase vehicle, so you will never get rid of it completely.
Mike
I have a copy (rather tatty) of The Journal of the Institution of Locomotive Engineers booklet from 1929 containing an article on an address (paper No.244) to the Institution by Harry Holcroft in December 1928 (locomotive design engineer of the GWR) on the whole topic of wheel coning and track.....after reading it you begin to wonder how the wheels manage to stay on the rails! Don't ask me to copy it...it runs to around 60 pages but I may be prepared to loan it to a suitable party).
My earlier message about the problems associated with "wind sail", etc. was more to do with the roller bearings involved (whether in IRW or normal axle applications).
John.
Sorry Tim, I didn't properly take in your last post "friction on curves caused by wheels scuffing as a result of the curve being too tight for the wheel coning to deal with".
Is it then possible to calculate the minimum radius which G3S standard coning can accommodate? And for Cliff's standard gauge-widened track? I assume it is not a simple calculation as root radius come into it too?
Mike
Mike
Have a look again at my post of 22nd August, where I report the minimum radii for the coning to work.
I'm happy to add any further detail if needed. I did not consider the fillet radius on the outside of the flange, as I considered it generally small enough not to be of significance.
Sorry must away for household chores!
Regards, Tim
Thanks Tim. I was away when this thread started and played catch-up when we returned - clearly I missed that bit. Apologies.
Seems that gauge widening does make a significant difference, at least in theory, although I accept not enough to solve the problem completely. As I will shortly be buying a large amount of track this is timely, so does anyone have any negative comments about gauge widening? Anyone had any problems at all?
Mike
Good question Mike. The other side of the coin is whether anyone has positively noticed any benefits of gauge widening? I refer to my earlier suggestion that unless our curves are bigger than about 9m radius, gauge widening does not save us.
I have a lot of second hand GRS track to lay over the next few years, in stages, but I'm not aware if any of it is gauge-widened, if indeed they ever marketed such a refinement?
Regards, Tim
Tim,
GRS do not supply gauge-widened track.
When chatting to Ted S who advocates gauge-widening (Cliff's track) I questioned why he thought it necessary, when GRS did not.
His comment was that GRS track gauge-widens by itself (lack of rigidity) but I have not tested this theory!
Regards,
John.
Of course this wasn't a problem in the past - the 3-point track gauge that the Society sold for use with it's rail and chairs automatically gave gauge widening on curves - and adjusted it to the curvature too. Pretty sure you organised their manufacture at the time Mike? :-)
Becomes more of a problem with plastic fixed sleeper/chairs - but CB sells gauge-widened (+1mm) for curves so it would seem sensible to use them.
IRW is an interesting idea but personally I'll stick to fixed wheel axles - but if you think the extra hassle is worthwhile Tim - then sure, why not - go for it.
Regards,
IanT
When Graham Pearce was here he said that Gauge Widening made his coaches easier to corner -you could feel the difference with your hand he said. As you know all my curves are gauge widened and I have "transitional straights" on some of them. I gauge widen on the inner curve.
regards
ralph
A treatise on independent wheelsets by Siemens Mobility 8)
www.mobility.siemens.com/mobility/global/SiteCollectionDocuments/Fen/Frail-solutions/trams-and-light-rail/Favenio_radsatz_einzelradfahrwerke_en.pdf
Robert, check the URL as I get 401?
Regards
Ralph
Quote from: cabbage on Aug 30 2017 19:46
Robert, check the URL as I get 401?
Regards
Ralph
Try it again now that John has kindly altered the %2F messages with /
Bob
Or this one . . . use the first URL listed :-\
https://www.google.co.uk/search?q=siemens+independent+wheels&ie=utf-8&oe=utf-8&client=firefox-b&gfe_rd=cr&ei=Qg2nWavdCMrv8AeMu5mgCQ
That's very interesting and takes my mind back to the early 1970s when I was at school and taken to a lecture at the AIMechE about APT-E which demonstrated that stability was improved with no wheel coning at all. Wonder what happened to that idea?
Mike
Bob, very interesting paper. I've wondered how trams in Nottingham get around incredibly tight curves in standard gauge. For those that haven't read it, in essence what it is saying is that IRW enables the tight curves without scuffing, but another trick is needed to assist with centering the wheelset between the rails. A reprofiled tyre with a "concave" profile instead of a straight cone causes any wheel flange that gets too near the rail to rise to a disproportionately greater rolling radius and assist in self-centering.
Mike, I think you were ahead of me when you asked about the radius to the flange! The above trick can be achieved using a large radius leading to the flange, so effectively the wheel coning angle is increasing as the flange approaches the rail.
I'm still wondering what to do with all of my Slater's wheelsets. The plastic hubs are a bit wee to bore for ballraces. The fillet radius to the flange is very small. Only half jokingly I ask if there is any appetite in the society for a new wheel standard?!? I think I know the answer to that!
Regards, Tim
Tim,
I would say that you keep your Slaters wheels "as is". If you are that concerned then order some slices bar from GLR and you can produce your own custom wheel. I don't think that we need a new std but it is a useful technique for people with tight curves.
The no cone idea comes from Sir Vincent Raven. It was employed on No. 13 as were quite a few revolutionary ideas for the time. My model has no coning but it is due for a rebuild and may be ground with "colonial wheels" for the drivers to help with leaves and fruit! It already has IRW in the front and rear bogies.
When I started this thread all I expected was a universal "no"... What have I started???
Ralph,
I have five coaches worth of Slater's wheels, so will be using them with some kind of IRW conversion. I am convinced now, having been very dismissive in the past!
Ralph has shown me a couple of ways of achieving IRW, namely a solid axle with two ballraces set into each wheel; and secondly to cut the axle in half then sleeve it with some close-fitting brass tube. Are there any other suggestions from anyone please?
Cheers, Tim
Here's a sample of a Slater's wheelset converted to IRW. I reamed the plastic centre then pressed in one of their own brass axle bushes, trimming off the blind end in the lathe to make the bush flush with the inside hub. Cut a groove on one axle end and assemble with a tiny circlip.
This clip is necessary to allow one wheel to "pull" the other to keep it away from crossing noses, etc.
I've asked Slater's for availability of spare axle bushes but no answer as yet.
19 more to go!
Regards, Tim
(http://thumb.ibb.co/ekovKF/IMG_0760.jpg) (http://ibb.co/ekovKF)
It's a neat solution Tim
Regards,
IanT
Thanks Ian, I've done another seven axles today, but am now held for more circlips (E-clips). Tim