Finney bogie question help...

[petermeyer]

...I have a couple of Finney 4-4-0 GWR kits on the go. The instructions say "Solder the 10 BA bogie pivot bolt in place". Later use washers on the 10BA pivot to achieve the correct ride height: "the bogie is mounted on its pivot supported by a suitable number of spacer washers".

Is this all there is to control the bogie? Is there no other form of slide? The bogie stretcher has an elongated hole so that allows side movement controlled by some steel wire. But does it just slide on washers and nothing else? Is that adequate and does it work?

Have I missed something?

[davebradwell]

As no GW folk have risen to a reply, I'll try and kick things off with my own experiences of bogies, although not on 4-4-0s. It is quite possible to make a bogie with correct side control which has a positive centre position but unless you have easy curves it can make the bogie prone to derail. Here I mean something better than the usual single piece of wire for side control which has very little sense of centre.

As someone who is averse to compensation I can only give my experiences of sprung locos - if the unsprung bogie is held on the track by a centre spring then it is less likely to stay on the traack than if it has separate springs each side and a flat slide on top (which doesn't allow tipping) to take the weight. There seems to be a simple rule that the further apart the springs are (or supports) the better.

So yes, the design will work but there's probably better ways that will stay on the track under more adverse circumstances.

I'm not suggesting you combine suspension systems which would seem an odd thing to do - a sort of 'can't make your mind up' solution. Hopefully someone will add their experience but I'm talking about stock that runs at main line speed on continuous circuits. Anything will work on a shunting plank.

DaveB

[petermeyer]

As no GW folk have risen to a reply, ...

So yes, the design will work but there's probably better ways that will stay on the track under more adverse circumstances.

I'm not suggesting you combine suspension systems which would seem an odd thing to do - a sort of 'can't make your mind up' solution. Hopefully someone will add their experience but I'm talking about stock that runs at main line speed on continuous circuits. Anything will work on a shunting plank.

DaveB

Thanks Dave for the reply. For my GWR Duke I created a slide for the bogie following discussions we had on here regarding my LNWR locos. After some tweaking and beefing up the spring wire this now runs. My layout is main line and the GWR 4-4-0 City will be an express loco running at main line speed on continuous circuit. The curves however are down to 3 foot in the non-scenic area. The Duke copes with this.

I had thought to copy what I had done with the Duke but wondered whether I should bother if following the City instructions achieves the result anyway. So I'll try that first and see if it works. Packing the pivot with washers just seems a bit lo-tech.

I wonder if anyone else has experience with these kits.

[Will L]

I have this theory.

Many people seem to think that, on the prototype, the side control springing on bogies and pony trucks is there to help steer the loco round corners. While I think that, apart from keeping the driving wheels from carrying more weight than the civil engineer will allow, the key purpose of carrying wheels is to stop locos from oscillating from side to side when travelling in a straight line. It’s the coned driving wheels that do the steering, although there can be a tendency to oscillate or box from side to side a bit. Big steam locos, with their long overhangs beyond the driving wheels, and their cylinders and large reciprocating masses on either side, are very prone to emphasise this boxing, and having something at the end which dampens down this tendency is highly desirable. Hence side control springs.

For our models we really don't have the same problems with locos boxing (not saying it doesn't happen just nothing like so much), while the coned wheel steering effect works as well for us as it does for the prototype. That is assuming all your drivers are weight baring and firmly on the track, i.e. compensated or sprung. Our drivers will find their own way round corners, and the friction of a simple sliding joint between a bogie/pony truck will be sufficient to dampen down any tendency to oscillate. So side control springs aren't necessary in our world, and as Dave said, unless very carefully chosen and very soft, more likely to derail the bogie than assist it.

Personally for an 4-4-0 I would favour a bogie pivot with no side to side movement at all, some lateral movement on the leading driver may be desirable, assuming there is clearance available to do that. Otherwise, and on your average 4-6-0, a bogie pivot with some allowance for side to side movement is likely to be required but there is no need to try and bias it to the centre with a spring.

So to answer Peter, the simple sliding contact point (pile of washers) between the bogie and the chassis spacer should be perfectly ok, and if you put the spring in, the most likely thing it will do is stop any side to side movement at all, which on a 4-4-0 may well not matter.

[Philip Hall]

I built a Finney M7 0-4-4T once and I think that was the system. I suspect your City will be the same; twin beams either side between the drivers and a single pivot supporting the bogie. It worked very well. It did make provision for side control with a spring wire either side of the pivot pin.

Having built (or converted from rtr) quite a few 4-4-0s I have found that the friction of a sliding interface between bogie and chassis is quite enough to provide the resistance we require. Most importantly the front drivers should not wobble at all as this helps no end in keeping the engine steady. My most recent one was a Bachmann City with Ultrascale wheels which I tested at a scale 100mph to see what City of Truro would have looked like years ago. It was rock steady, pulled approx 1.5 kg but it must have been frightening on the footplate in the dark all those years ago!

Philip

[Phil O]

I have several Finney 4-4-0s in the stash to build, I have only opened the boxes to insert wheels, motor and gearbox. Whether I get to build them remains to be seen, my kit building is on a glacial scale, except for wagons. My only experience of 4-4-0s is a 00 gauge Ks Bulldog that has a centre pivot, and no side play, it runs OK on Peco track.

[davebradwell]

I'm beginning to wonder if I/we understand the question. There is talk of a slide - your Finney bolt with its washers is a slide. If you were to use the kind of flat plate slide I use on my sprung bogies you'd have 4 point suspension and we don't want to go there again. As has been pointed out, the Finney kit produces a 3 point suspension - the 2 pivots for the equalising beams and the rocking bogie centre. Yes, the flat slide would be valid if you sprung the bogie axle bearings but gives a mix of suspension systems, perhaps there's no harm in that. You might consider making the driving axle beams springy to be consistent.

At 3ft radius you'd find it difficult to design side control that had a real effect. The bogie will require quite a swing so at lesser offsets the restoring force would be small. My thinking on this question is different from those outlined above - after the loco has gone round one of your curves, I want the thing to be restored to pointing straight ahead with bogie pivot central but easier said than done. Nothing to do with the front oscillating, round wheels should sort that.

Yes, coned wheels should centralise in our track, given a little friction damping but I suggest reality wrecks this. Our track just isn't straight enough, our axles not parallel enough or at right angles to the centreline even if both wheels are the same size so it's likely that they run along one rail until a wiggle pushes them to the other side and they drift back again. Fortunately, it doesn't seem to matter but in extreme cases we have a wheel searching for a defect in the rail.

The temptation to build a 4-4-0 with no side movement on the bogie is interesting and I've wondered about this. Weren't the first 4-4-0s like this and I suspect that the American style locos with their equalised springing had a rocking centre support and no sideplay? Quite an ask to get it all round 3ft curves, however. In the end, I'd never use a bogie with single central support for reasons outlined in my first reply.

All in all it's more important that you build the model than be put off by multiple suggestions.

DaveB

[Will L]

...Yes, coned wheels should centralise in our track, given a little friction damping but I suggest reality wrecks this. Our track just isn't straight enough, our axles not parallel enough or at right angles to the centreline even if both wheels are the same size so it's likely that they run along one rail until a wiggle pushes them to the other side and they drift back again. Fortunately, it doesn't seem to matter but in extreme cases we have a wheel searching for a defect in the rail....

Practical experience disagrees with that, my C12 (4-4-2 with pony truck only along for the ride) routinely ran on Knutsford East throughout the years of its exhibition carer. A very nice runner (CSB of course). Any 4-4-0 that did what you suggested would be instantly and obvious running at an angle to the track. No sign of that on the C12, Dick Petter wouldn't have let it near the layout if it did.. I think all the evidence is that the coned wheel effect is alive, active and reliable.

All in all it's more important that you build the model than be put off by multiple suggestions.

Agree with that

[petermeyer]

Thanks all. Plenty of food for thought here. I'll carry on with the build and see how it works out...

In the meantime this thread has prompted a reassessment of some of my other 4-4-0 builds. More on that another time.

[davebradwell]

You've found a very good example there, Will and my Pacifics and 4-6-0s just can't get out of line to the same extent. A quick calculation shows you can skew the front buffers almost 2mm each side of the centre with just the clearance in the rails so certainly something is keeping it straight. I gave up on side control years ago and haven't noticed any difference with locos still pointing the way they're going. Nice to copy a bit of the prototype occasionally.

I'll go along with your coning theory if:
Wheel diameters on an axle match to within about a thou' and a half (0.038mm)
Curve is above 5-9 m range according to wheel size. Below this coning is inadequate and wheels slip.
Wheelbase matches within around 0.1mm each side
Track deviations from true alignment significantly less than 0.36, the clearance in the gauge.
Frame lozenging, where one is in advance of the other, possibly around 0.15 but I haven't considered possible side-effects in pointwork.

Each number assumes all else is perfect. Small errors in each category can add up but some may cancel. There could be others I've missed and it's likely different numbers are possible. What matters is that the numbers are in the achievable range without having to do do anything special. Coupled wheels should all be the same size to avoid strain on the rods. I'll confess to being biased - years ago was influenced by a speaker from Derby Research on the evils of coned wheels and 16t mins which were throwing themselves off the rails with increased frequency as CWR were spresading.

I would say that matching of wheel sizes is the most significant issue and I've had trouble with this over the years, even resorting to skimming sets to a common diameter. I'll throw in that I've occasionally used non-coned tyres and they seem to work just as well, although with rather longer w/bs than Will's C12. Measured a set of Ultrascales just now and struggled to find any variation so they're as good as my measuring equipment.

Conclusions? Looks like it's worth making an effort during chassis construction - hardly mind blowing! Side control probably just novelty value.

DaveB

[Crepello]

Didn't Dick Ganderton once (50+ years ago?) successfully demonstrate coning effect with a GWR railcar
with flangeless wheels on an early P4 layout of Ashburton, and scrutineered under exhibition conditions?

[Philip Hall]

I followed advice from WE Ward-Platt in an old Railway Modeller article to try parallel treads and turned down some old Jackson wheels by eye. They run very well and I would do it again.

Philip

[Will L]

I followed advice from WE Ward-Platt in an old Railway Modeller article to try parallel treads and turned down some old Jackson wheels by eye. They run very well and I would do it again.

But I bet the flange wasn't vertical and at right angle to the tread. What people tend to forget is that the flanges make a coned wheel just at a much steeper angle than the tread. I tried using Meccano flanged wheels (flat tread vertical flange) as railway wheels as a kid. Dosen't work.

I'll go along with your coning theory if:
Wheel diameters on an axle match to within about a thou' and a half (0.038mm)

the six Sharman's I just mesured were well within that

Curve is above 5-9 m range according to wheel size. Below this coning is inadequate and wheels slip.

Your forgetting that the flange is just a continuation of the coning, only steeper

Wheelbase matches within around 0.1mm each side
Track deviations from true alignment significantly less than 0.36, the clearance in the gauge.

I'd be interested to see on what basis you justify the last two.

[Philip Hall]

But I bet the flange wasn't vertical and at right angle to the tread.

I don't think I implied that, and using a Jackson wheel as a basis wouldn't give you a right angle flange, clearly that's not a good idea. I simply skimmed the tyre surface parallel, simply because I don't (easily) have the facility for taper turning, and didn't at the time have a form tool. I blended the Jackson flange into the new tyre surface, and reduced the depth with a file. WE W-P recommended an angle of 120 degrees, if I remember correctly, but I just judged it by eye. He also said that extensive experiments led him to think that having a radius where the flange meets the tyre wasn't essential, but I didn't carry mine that far.

Philip

[petermeyer]

Following comments on this thread, I added, in addition to the "slide", a slim washer from the fret of my 4-4-0 Finney Duke to the bogie pivot and the bogie now rests on this. This of itself has not changed the performance so I conclude that the washer pivot system may work on the 4-4-0 City.

The tweak to the Duke bogie that I alluded to earlier was that I found that the elongated slot in the stretcher was tight on the pivot and having eased that it went round corners better. I have not long had the roundy layout that I can observe trains running on so this has been a benefit in improving performance. The Duke has no side-play on the driving axles. Firstly because I probably didn't think about it and built it before I had a layout with 3 foot curves. Secondly, as an outside frame loco, there is not much room for maneuver. In addition to the flexi-chas inner bearings there are also bearings on the outside frame. This plus the outside cranks means it's all very tight. So I think that easing the slot on the bogie stretcher gave some side-play that was needed. I can only state that this change did improve performance but in technical terms I can't say how.

I have since discovered that a major hindrance was the tender which, apart from the drag, whose front steps are fouling on the loco steps low down around the tightest of bends. A slightly longer tender connection is possibly the remedy. I found this out when the loco accidently zoomed off sans tender running much better than it had before.

[Will L]

But I bet the flange wasn't vertical and at right angle to the tread. (i.e. flat and forming a right angles to the tread) edited to clarify

I don't think I implied that, and using a Jackson wheel as a basis wouldn't give you a right angle flange, clearly that's not a good idea. I simply skimmed the tyre surface parallel, simply because I don't (easily) have the facility for taper turning, and didn't at the time have a form tool. I blended the Jackson flange into the new tyre surface, and reduced the depth with a file. WE W-P recommended an angle of 120 degrees, if I remember correctly, but I just judged it by eye. He also said that extensive experiments led him to think that having a radius where the flange meets the tyre wasn't essential, but I didn't carry mine that far.

You didn't, but I guessed because without the angled flange i doubt they would have worked.

[Philip Hall]

The temptation to build a 4-4-0 with no side movement on the bogie is interesting and I've wondered about this.

I just spotted your comment, and realised that I did once build a 4-4-0 without sideplay on the bogie pivot. It was a NBR 'R' 4-4-0T from the Riceworks kit. It was a long time ago because I first heard about the kit when talking to Iain at the Manchester Finescale Exhibition! It was compensated, with a fixed, driven rear axle and a beam between the front axle and the bogie pivot. The bogie was mounted on the end of the beam and was itself compensated with a rocking axle at the back end. The front axle had a little sideplay, and in theory there was no sideplay on the bogie, but in practice there was a little play in the beam pivot which probably helped a bit. It went around quite sharp corners quite happily but then it's not very big, and these days it isn't called upon to go round anything sharper than 4'6".

I could be tempted to try something similar on a 4-4-0 tender engine one day if the need arose because it does seem quite stable.

Philip

[Will L]

I'll go along with your coning theory if:
Wheel diameters on an axle match to within about a thou' and a half (0.038mm)

the six Sharman's I just mesured were well within that

Curve is above 5-9 m range according to wheel size. Below this coning is inadequate and wheels slip.

Your forgetting that the flange is just a continuation of the coning, only steeper

Wheelbase matches within around 0.1mm each side
Track deviations from true alignment significantly less than 0.36, the clearance in the gauge.

I'd be interested to see on what basis you justify the last two.

Further to that and with more thought (I shouldn't have replied till this morning).

I'm always surprised when otherwise fine, upstanding, intelligent, skilled and otherwise knowledgeable modellers start denying that the coned wheel effect works for us.

It has been a key element of the way railways work since somebody thought better of plate ways. It’s worked for all sorts and sizes of railways ever since. Why should it not work for us?

At that point some bright spark will say, the physics don't scale. Well I'm sorry guys, but as the coned wheel effect is based on the linear distance round the edge of the wheel where it is in contact with the rail, and the linear distance along the rail, our scaling factor applies equally to both so makes no difference to the conned wheel effect. In this case the physics does scale. It is true the physics doesn't scale when you start considering what happens when the wheel flange hit the rail on a corner. The key element then is the weight on the wheel divided by the force between rail and flange caused by going round the corner. The Nadal Formula if you’re interested. Both involve multiples of the scaling factor which is why "the physics doesn't scale". However, as the mass is affected by the cube of the scale factor, and the lateral force by its square, the net effect seems to work in our favour and explains something we have all observed. When nothing else interferes, scale trains can go round sharp corners much faster than the prototype.

As to Dave's objections, if the effect is so dimensionally critical, how come most of our loco's do go strait down our strait track? As to the corners, I agree that it is quite likely that the wheels will work their way over until the flange comes in to play, but that is still a coned wheel and one who's diameter increases rapidly. The wheel may slide a bit, but only until it is far enough up the flange for the distance travelled to be the same as the diameter round the flange at the point of contact. It will keep on turning, being firmly attached to the one on the other side. At that point its down to Mr Nadel as to whether it rides up further or not. See the last sentence of the previous paragraph.

[davebradwell]

Went out for the day to get a bit wet and returned to mayhem on this thread. It'll take a few goes, I think.

First to Petermeyer who started it all with what's turned out to be a relatively straightforward problem. I think you had a decent response to the side control question and appear to have the sliding action sorted out. If you find the bogie has a tendency to derail we can work through some of the alternatives. Yes, tenders can be a nightmare - have you discovered fallplates and their tricks yet?

....and so to the multiple diversions. I never denied that the coning effect worked, just that it was likely to be overcome by inaccuracies in the chassis and track, nothing to do with scaling physics. Returning to Saturday night's question I looked up the clearance between wheelset and rail - 0.36 min - and used this to find the difference in diameter on wheels coned at 3 deg. This gave the 0.038mm figure so I said that if the wheels differed in diameter by this much it would overwhelm the effect of the coning, in one direction at least. Rounding up the 0.038 to 0.05 (diameter difference) to allow for some gauge widening on curves led to the limiting radii for coning to work and I used these figures to derive a parallelism spec. Finally, keeping the axles at right angles to the track the 0.36 clearance figure with an 8ft wheelbase gave a number for the amount of loznging permitted. I wasn't really concerned about the exact numbers but was just curious to see if the general order was achievable. I'm not convinced we know as a group. I'll add that it's quite possible there's errors in the sums but they should be in the right ball-park. They aren't real tolerances, just the dimensions that will prevent the coning working properly. Remember each assumes perfection in the others so they really need sharing out to give a total set of limits. I used to get paid for doing stuff like this!

An opportunity for a reminder that such numbers also apply to wagons and coaches if adjusted for the bearings being further apart.

Back to your most recent, Will, I recall an article in SNews which suggested wheels went round corners halfway up the flange but couldn't find anyone that agreed. In my book, once the tread leaves the rail surface it's going to end up in the ballast so we'll have to differ there. As for Nadel, so often quoted in those 'P4 can't work articles' I'm happy to hurl my Gresley BG round my metre curve at as near to 200 scale mph as I can to prove he's fit and well as long as you remember to put the g in the sums and that it's actually not quite 3 mph. I'll also remind you that you've done enough theory to know that the coned wheel on rail is actually a pendulum and in the perfect conditions found on the prototye will hurl the 16t min off the track at above 40mph. Modern vehicles have dampers to control this and I'm sure we have plenty of friction and/or errors in our models to prevent hunting.

Perhaps stock with larger errors than the above just moves over to one rail and runs along it. Seems a satisfactory state of affairs.

Final comment for the night is on PhillipH's description of the Rice compensation - don't you think that all this complication and extra beams just shows how simple springing is? Much of it comes from the rigid driven axle which was needed because we only had Romford or Ultrascale gears then and open-framed motors. Neither offered the essential gearbox that enabled the driven axle to move which in turn now permits better/simpler solutions.

Suppose I'll be defending more things I didn't say tomorrow.

DaveB, for now!

[Chris Pendlenton]

Yes Will, I dare say the physics of coning applies in 4mm scale but unfortunately the physics of other well out of scale factors such as Dave mentions rather dominate the issue.
Not so far mentioned is that, in my firm view, the bogie or pony must carry some of the locomotive weight if stable running is to be achieved. I touched on this in my article last century in MRJ 6 and again in 28 and much subsequent experience with many big locos latterly with big trains at speed has not caused any change of mind. I believe in a pair of flat mating surfaces as wide as the mainframes on the top of the bogie and the bottom of the frames above which keep the bogie frame firmly horizontal and offer a degree of lateral damping when curving. The suspension should be directly over each axlebox within the bogie frame. When curving at the maximum travel of the bogie stretcher slot, the outer wheel flange is bearing hard against the high rail and acting like a tripping stop or pivot to the side pressure causing the inner wheel to want to lift. Fortunately it is best inhibited by that inner wheel being sprung from directly above with no weakening of its effort by a bogie frame being tempted also to tilt against a stack of small diameter washers.
As to the weight to be carried I follow a ballpark proportion seen in full size weight diagrams whereby each carrying wheel bears about half the load of the driving wheels.
When building my A2/3, which has a very long overall wheelbase but with drivers bunched tightly together in the middle, this whole issue of tight curves and long engines revealed an interesting trade off between road holding and haulage ability. Loading the bogie for trackholding could mean that between it and the rear cartazzi truck the driving wheels could become unloaded especially in slight dips. Because the driving wheels had individual grub screw adjustable suspension I was able to tune things to give an optimum result whereby the load up a 1 in 120 curved at 4' 6" went up from 9 to 13 coaches.
Chris P

[Hardwicke]

Not so far mentioned is that, in my firm view, the bogie or pony must carry some of the locomotive weight if stable running is to be achieved...

I believe in a pair of flat mating surfaces as wide as the mainframes on the top of the bogie and the bottom of the frames above which keep the bogie frame firmly horizontal and offer a degree of lateral damping when curving. The suspension should be directly over each axlebox within the bogie frame. ...

As to the weight to be carried I follow a ballpark proportion seen in full size weight diagrams whereby each carrying wheel bears about half the load of the driving wheels.

Chris P

Very interesting and useful as I'm building my second hand Midland Compound and my Airfix West Country also needs it's bogie attending to. Neither have real suspension and the West Country has a tendency to derail on some, but not all points. It followed Guy Williams' suggestions that it doesn't need much suspension. Then again Pendon isn't P4.
Excellent article in MRJ 300 Chris

[wakefield]

I have been following this thread with interest. Some of the science is out of my league but interesting and informative nevertheless. One component that has not been mentioned so far is that the rail is tilted inwards at I think 1 in 20. This I assume is to offer a flat running service to the coned wheel tread. I seem to remember that flexi track has this built in but how accurate and consistent I would not know.
Maybe this does not affect the physics that control the coned wheels.
Anyway, just saying.
Mike Wakefield.

[Ian@Exton]

As I don't think anyone else of a Western persuasion has responded directly to Peter's question I can offer a belated response.

I have built a Finney Bulldog and just followed the instructions in the kit. It works fine round my emerging layout of Dulverton, which has a minimum radius of 1200mm. It did take a little careful adjustment with washers to get the ride height correct. The clearances are pretty fine, as I guess they were on the prototype. As you can see in the picture below the loco sits nice and low and seems to 'glide' along.

I am building a second Finney Bulldog, and will probably do the same again - the only amendment I may make is to sleeve the 8 BA bolt which forms the bogie pivot with brass tube, and widen the slot in the bogie accordingly.

So good luck with the rest of your build.

Ian

[Will L]

... I never denied that the coning effect worked, just that it was likely to be overcome by inaccuracies in the chassis and track, nothing to do with scaling physics.

No you didn't, but I do find the "The physics doesn't scale" argument gets trotted out on this one quite regularly so I was getting my retaliation in first. It wasn’t aimed at you. I do agree it won't work unless each wheel is carrying it’s own share of the weight, but we believe in proper suspension don't we? So while I do accept that there will be occasions when the effect is overcome, the point is surely that it does work much of the time and will reassert itself as soon as conditions permit. So we shouldn't ignore it, rather accept it as another reason why providing suspension improves ride and performance.

...I recall an article in SNews which suggested wheels went round corners halfway up the flange ....

.
So I'm not the only person to wonder about the implications of the flanges forming a coned wheel. Not sure how you prove or disprove this, but I presume there is a reason why, when check rails are used to guide wheels round corners, they operate on the flat back of the wheel.

As for Nadel, so often quoted in those 'P4 can't work articles' I'm happy to hurl my Gresley BG round my metre curve at as near to 200 scale mph

We can agree that this works in our favour and the P4 sceptics were talking ... as usual?

I'll also remind you that you've done enough theory to know that the coned wheel on rail is actually a pendulum and in the perfect conditions found on the prototype will hurl the 16t min off the track at above 40mph.

Like many such mechanisms that tend to self correct, there is a hysteresis effect. Whether the friction in the works dampens it down to nothing or it oscillates out of control, is all dependant on whether you hit a resonant frequency. The latter certainly can happen on the prototype but I've yet to see a model do it. Whether this is due to more than adequate frictional damping, or never approaching a resonant frequency, is another question, but I suspect that small sizes beget high resonant frequences we get nowhere near.

In case any of you are wondering I've been otherwise engaged.

[Will L]

I have been following this thread with interest. Some of the science is out of my league but interesting and informative nevertheless. One component that has not been mentioned so far is that the rail is tilted inwards at I think 1 in 20. This I assume is to offer a flat running service to the coned wheel tread. I seem to remember that flexi track has this built in but how accurate and consistent I would not know.
Maybe this does not affect the physics that control the coned wheels.

This is another reason why, often suggested by those who don't want to believe that coned wheel effect can work for us. As far as I can work it out matching the rail inclination to the wheel coning angle is, as you suggest, just to even out the ware on the rail head. The coned wheel steering effect works whether you’re rail is tilted or not.