Finney bogie question help...

[wakefield]

If one had the time or inclination ( excuse pun) you could turn a set of wagon wheels with no coning and vertical flange and see how well it runs. I suspect not at all well.
Mike

[Philip Hall]

I think that's right, coning works whether the rail is inclined or not. I have some Exactoscale FastTrack bases where the rail leans inwards on one side and outwards on the other! The gauge remains fixed and it all works just fine. Actually the only result of a parallel tread wheel is that there is a little more play between rail head and railhead. Depending of course on the angle of tread to flange.

Most of us of course will not have the option of experimenting with flange profiles, if indeed it might be deemed necessary to experiment. I just do it for fun.


Philip

[Will L]

...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.

Yes I think you me and DaveB all agree that, for locos with a long wheel base and a relatively short driving wheel base, carrying wheels which really do support some of the loco weight can be highly desirable. That includes both the locos you describe and the 4-4-0s which were the original subject of this thread. As an aside, we would also agree that springing is the best form of suspension, although we might not agree on the best way to do it.

It would appear we are also happy that while frictional lateral damping of bogie movement needs to exist, spring controlled centring is not critical (and probably not necessary). A fair demonstration that the coned wheel effect is in operation and useful is the fact that my C12 (which is effectively an 4-4-0) with lateral freedom on the bogie and no side control springs, will run strait down the middle on plain track (which doesn't exceed Dave's curvature limit). We have argued the toss about what happens at corners but isn't the strait line performance just as important?

...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.

I think your right about the sort of weight distribution you suggested across loco drivers and a leading bogy, though I do wonder how you quantify exactly what the distribution is, when using individually adjustable springs. Easily doable with a CSB fitted loco of course (sorry my agenda is showing again).
.

..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.

As a practical performance issue, I doubt the value of putting loco weight on most pony trucks and whether this materially affects running stability (in most circumstance, but I'm sure we could come up with exceptions), while it can have implications for pulling power as you're and the LMS's* experience indicate.

*Pacific locos were notorious for "sitting down" on their pony trucks when starting heavy loads particularly up hill. As a result, a Scott could start a bigger train out of Euston than a Coronation.

[Will L]

---I agree very much with Terry's approach to potential recruits to our world. I have felt for some time that we do potential recruits no favours by suggesting that converting a RTR diesel to P4 and buying some track is a doddle and the road to Nirvana... etc

Oh I do so agree, but perhaps on the wrong thread?

[Philip Hall]

Thank you Will, senior moment time! Now amended and put in the right place.

Philip

[Will L]

Thank you Will, senior moment time! Now amended and put in the right place.

I just find myself wishing for moments when I'm not senior

[nberrington]

Thank you Will, senior moment time! Now amended and put in the right place.

I just find myself wishing for moments when I'm not senior

I just saw a quote from an ageing rocker: “it was way more fun being in my twenties in the seventies than in my seventies in the twenties!”

[Julian Roberts]

Age is an issue of mind over matter. If you don't mind, it doesn't matter.

[Chris Pendlenton]

Referring back to Will's post, good to see some convergence on this.
I would however urge that we treat pony trucks in just the same way as bogies – why not, its no more work and inhibits the pony from wiggling and bouncing around on exciting bits of track, under yawing long engines. Its purpose is less to support the loco but the other way round, the loco weight steadying the ride of the truck. Another incidental reason is that the pony frame offers a well grounded stable foundation for mounting an AJ coupling, which one needs to think about for freight moguls in particular.

In this context I have to confess I’ve never managed to get my head round how it works with carrying wheels, how the springing installed on bogies and trucks affects the mathematics of anchor spacings and heights. I have never actually built a csb chassis but I acknowledge their simplicity and popularity, and Will's service to promoting springing as an advance on compensation. My sticking with individual springing has to do with three things:
It is discrete; each axlebox and spring is self contained and does not require introduction of frame stretcher clearances.
Ride height and trim is finely adjustable by screws. The recommended method of adjustment of a csb, by using different wire gauges, only alters the stiffness or weakness of the suspension. Grub screw adjustment alters only its ride height and are likely to be especially useful for 4 4 0s, 0 4 4s etc as well as Pacifics in matters of stability and trim. There may be cases where it is found beneficial to slightly increase the loading of outer driving wheels if sharp curvature and mini rail summits are a feature, say in colliery yards.
I worry about installing anchor centres on frames before one really knows where the centre of gravity is going to end up. It seems easier to adjust springs than to try to relocate lead ballast if you get the c of g estimate wrong or have to do a later alteration like removing ballast weight to get a sound speaker and chip in. Or if you like having tenders leaning on the drawbar to increase traction. I don’t know how sensitive the csb is to such alteration but the precise mathematics of setting up prompt the thought.
Chris P

[Chris Pendlenton]

Typo, second para should read " how csbs works with carrying wheels..."

[nberrington]

This is a very timely discussion for me, as I contemplate building a Rumney 2-6-0 chassis. Justin has offered a few options for the pony truck, but I dare say I find myself somewhat intimidated by the whole thing……

[davebradwell]

Indeed, Chris, I came up with an apparently sound bogie design early in my adventures thanks to your help but pony trucks have never been quite as reliable. Copying the shape of a full sized bogie usually gives a low wide slide for stability but with a pony the struggle to obtain enough travel can result in a high narrow slide that's trying to tip and springs that are closer together than the ideal. I think, at last, I've conquered its derivative the Cartazzi (which can be unco-operative when reversing) but as it can take a long time to confirm that changes in design give improvements in performance I can't escape the possibility that it might just be playing dead. These things aren't black and white, everything works to some extent but an improved design eventually reveals itself by staying on the track for longer when increasingly challenged.

It's interesting that Sir Nigel was becoming dissatisfied with his bogies which had a ball and socket centre support in the slide which offered no resistance to rolling where track maintenance was below par. A number of experiments were carried out on A4s and I think D49s using forms of side pad, either as supports or to limit roll. His swing link pony truck was implicated in a serious V2 derailment and replaced with a wide slide and separate side control.

DaveB

[Chris Pendlenton]

Ah, swing links, now there's a challenge. Even just to understand how they work. I think I sussed them as trying to raise the inner side of a curving engine which of course fought back and simply applied more weight and pressure on the inner side springs, countering any tipping moment. In a moment of excess I did sketch out a model design but really.
As it is, a conventional wide as possible pair of mating bearer plates and sprung axleboxes has served well enough under a K3, K1, 4MT, 4MTT V3, L1 and of course my V2 whose length might challenge a pony truck but as you know 60949 gallops round my circuit and its various junctions at around the ton without demur. Ditto the sprung Cartazzis on fast moving reversing light engines, a rare eventuality.
Chris P

[Will L]

Sorry, I took a while to reply as I thought you deserved a properly considered response. Long posting warning.

Referring back to Will's post, good to see some convergence on this. I would however urge that we treat pony trucks in just the same way as bogies – why not,

I think we are basically treading the same path but I remain unconvinced about putting loco weight on pony trucks, particularly for pacifices where I do have another reason not to include them, see below. In my view the leading bogie is more efficient at controlling lateral instability then the pony truck could ever be, but I accept that I don't build locos this big.

In this context I have to confess I’ve never managed to get my head round how it [a CSB] works with carrying wheels, how the springing installed on bogies and trucks affects the mathematics of anchor spacing and heights. I have never actually built a csb chassis but I acknowledge their simplicity and popularity,

In theory a pony truck or a bogie can just be another axle under the CSB wire (a bogie would count as one axle) and these days the spreadsheet will allow you to vary the percentage of the weight carried by any one axle. However while fitting CSBs to the drivers is a relatively simple and straight forward process, particularly given the product support from suppliers like Highlevel, supporting carrying wheels is more difficult. First comes the need to allow the axle some lateral movement on an ark, then some dimensionally precise engineering to ensure the rail to wire dimension is the same as for the drivers, as the calculations are meaningless if they are not. We would want to be accurate to better than .1mm. For that reason I haven't (yet) done it, although I do have plans for a 2-4-2 with radial trucks and all 4 axles under the wire.

However there is a much simpler solution for carrying some loco weight on a bogie or pony truck which is not supported by the CSB wires. The thinking on this is explained in this post CSBs a question of Gravity. While I can play this trick with the Chassis supported between two points (the Centre of Load of both driving wheels and bogie, read the post) I can't do it for three. Hence I'd opt for giving a pony truck a free ride.

My sticking with individual springing has to do with three things:
It is discrete; each axlebox and spring is self contained and does not require introduction of frame stretcher clearances.

true

Ride height and trim is finely adjustable by screws.

What I have a problem with is

..Grub screw adjustment (on individual springs) alters only its ride height..

I've thought long and hard about the performance of sprung chassis, and I can't see how the adjustment of an individual screw can not have an effect (which is going to be hard to quantify) on the weight distribution across all the sprung wheels,.

The recommended method of adjustment of a csb, by using different wire gauges, only alters the stiffness or weakness of the suspension.

Yes, as opposed to adjusting each spring individually, it adjusts all the spring spans together so the balance of the chassis, as produced as a result of the initial design, is not affected. Exactly what you should want surely.
I do have to say that perhaps too much has been made of the use of a wire change as an effective way of adjusting ride height. In practice you only have about 0.3 mm to play, with which can hardly make a significant difference.

The whole CSB design process ensures that, given the wire is right for the actual loco weight, the axles will be very close to the designed chassis axle centre line (when static on a flat surface!). So if you have a problem with ride height, then it's down to a build error somewhere (fit between chassis and body?) and that is what requires attention. Given the quality of your modelling I doubt build errors of that sort are a common problem. I can only assume that the prime requirement of your screw adjustment is to achieve the axle alignment with the axle centre line that the CSB chassis gives you by design. Having got this adjustment right which also implies that the load on each axle is as it should be (or the chassis wont sit level) I'm not then sure why you would want to adjust them further.

I worry about installing anchor centres on frames before one really knows where the centre of gravity is going to end up. It seems easier to adjust springs than to try to relocate lead ballast if you get the c of g estimate wrong

Ok, yes this is dependant on having the CofG in the right place, but then, that is also exactly where you want it to be if you want (as a sprung suspension user) to ensure an even distribution of weight across the driving axles and hence to ensure the maximum pulling power. Read on right down to the end of that thread I gave you above for a discussion on that one too. I would say it is probably better to sacrifice a little body weight to achieve the optimum CofG position, than adjust the springing to suit a non optimum weight distribution. However, given no other practical choice, or if modelling the original locos weight distribution is seen as part of “getting it all right”, the spread sheet will allow you to specify what ever weight distribution you fancy and will then give you the right CofG location to go with it.

I know the inability with CSB to adjust axles individually worries DaveB too. I can only ask why you feel adjustment should be necessary. The CSB design method ensures that each driving axle gets a specific (usually about equal) share of the loco weight. Given that going away from the optimum equal share will reduce the available pulling power, why would you want to do that.

There may be cases where it is found beneficial to slightly increase the loading of outer driving wheels if sharp curvature and mini rail summits are a feature, say in colliery yards.

As these are some of the very things we put suspension on our chassis to overcome, if our suspension works, why should we need further adjustment to overcome them?

or have to do a later alteration like removing ballast weight to get a sound speaker and chip in. Or if you like having tenders leaning on the drawbar to increase traction. I don’t know how sensitive the csb is to such alteration but the precise mathematics of setting up prompt the thought.

I have to agree that having designed and built a CSB chassis, I would have significant reservations about doing things to the weight balance of a loco to get a sound system into it. However, as I am aware of the impact on a significant shift of CofG, I'd be looking for a way to ensure I didn’t do that, and I would suggest that anybody with a sprung chassis would have similar problems and risk a significant reduction in performance if they don't do the same.

As to transferring weight from the tender, I don't see that as compatible with CSB chassis design. I am now used to knowing where the effective CofG is and the actual weight on the driving wheels, I wouldn't want to go back to guesstimating such things. My personal modelling journey has included doing such a loco which had compensation and other problems of its own. While I learned a lot from the experience, I wouldn't go back there now and I'd rather put the motor in the tender and get the loco weight and balance right.

[davebradwell]

Gordon Bennett, Will, you've been very busy - I'm sure we've been over this stuff before but I just don't think any of it matters. I set springs with loco inverted and adjust all main axleboxes to same height. Placed on the track the springs all compress the same amount so will share the load well enough. Of course a single adjustment will change the rest but not significantly and after setting them as above why would I do that - I'd either adjust 2 at the end to alter pitch or all along one side for roll.

I can't see why you would design a 2-6-0 with an inferior approach to its carrying wheels when compared with a 4-6-0. We have amongst us a V2 (2-6-2) with floppy trucks front and rear and their track holding is certainly inferior to others treated more diligently. Yes, it runs through ordinary turnouts but at speed or in dark corners of King's Cross station throat it fails to do its job.

Strangely, you may think, when starting a loco build I give absolutely no thought to what it might weigh. I've ensured all bits of the motion will miss each other and ensured coupling rods and axle centres are correct to drawing within quite tight tolerances so no jigging. All my chassis have the axle centreline marked with reference points but I haven't seen them on any other kits. I add weight - usually as much as possible - and sort spring height adjustment out later. It works for me and I like to put the springs where they should be when possible.

You've done a fine job making springing accessible to many, Will but you don't have to pick holes in other approaches that were in use long before anybody said csb. Our system has its advantages and disadvantages, just like csbs or any other method that may be out there. Essentially a spring is a spring and all are equal.

Not sure how this relates to Finney bogies!

DaveB

DaveB

[Will L]

I can't see why you would design a 2-6-0 with an inferior approach to its carrying wheels when compared with a 4-6-0.

I didn't mean to imply that, Bogies may be are easier to do but the same thinking applies to carrying weight on a single pony trucks. What I can't get to is two of either.

Strangely, you may think, when starting a loco build I give absolutely no thought to what it might weigh.

And its the idea that you need to do that I'm trying to counter. What a CSB chassis user should eventually be concerned about is where the CofG ends up, what ever the final weight will be.
Another thing I was trying to point out is that even with individual springs you could be well advised to be similarly interested.

You've done a fine job making springing accessible to many, Will but you don't have to pick holes in other approaches that were in use long before anybody said csb.

I'm really not trying to do that, I was just answering the questions Chris asked. When people have a methods which works for them and which they are familiar with, its no surprise if they continuing to do it that way.

[Chris Pendlenton]

Thank you Will for taking so much trouble responding. I have read your linked item on carrying wheels and see that your approach is to move the C of G to embrace the bogie or pony in the overall equation though note you are discombobulated by engines with carrying wheels at both ends. I also note that Russ Elliot, in a related piece seems to advise against including carrying wheels in a csb design, that a sufficiently forward foundation point is impractical, which perhaps implies such wheels should not carry any loco weight and just “go along for the ride”. Which in turn implies at least to me that csbs, while fine for 0 n 0 chassis, as you term them, are perhaps out of their depth for more complex types. Incidentally, you miss my point about pony wheels, which was not that they offer useful lateral guidance or weight support but that the loco weight bears on them through an “inverse” suspension that keeps the thing on the rails. And also that such a stabilised frame is essential for mounting Jackson couplers if used.
I began springing locos a long time ago (MRJ 6 refers) in flight from rigid chassis and I worked on the principle that any springing, however imperfect, was better than none and began empirically from an opposite start point to yours with csbs, whose mathematical exactitude is admirable if daunting. My approach was nevertheless careful and employed measurement of spring rates all empirically found on the simple rig seen in MRJ 6. This was not nearly as precise as your csb plots, whose sensitivity neverthless to tiny errors of placement or C of G seems a bit startling, especially after reading your own account of the 04 whose trim was catastrophically affected by the addition of two cast metal crew! It makes me wonder what percentage errors are tolerable. Does the articulated nature of a continuous beam double or triple its sensitivity to misplacement? I’d note too that using handrail knobs as anchors is fine until you get supplied with some whose hole is not central; I have lots like that.
Individual springs seem quite tolerant and while the theoretical perfection of adhesion is a fine thing I have to tell you that a spring on two of my engines fell out and they both ran for months with no detectable impact on road holding or tractive effort! One should mention too the Brassmasters /Comet system with unadjustable coil springs that seem unperturbed by inexact C of G locations, however ideal. My Ivatt 2 6 0 runs very well.
So having set the hornguides and axleboxes to an approximate unloaded position in the way Dave describes I can then adjust final height under finished body weight by simply turning the screws. Evenness of adjustment is not a problem; if the engine is down at the front I wind the leading driver grubscrews up by say one turn, the centre pair by half a turn and leave the rear as was. Same approach if it leans. I sight them with a steel rule. If you have sprung carrying wheels it is less easy to adjust their often simple cantilever springs than the grub screwed drivers so it may be that adjusting the balance of weight distribution between drivers and bogies is easier done on the drivers, as well as crude settings on the bogie/pony done by packing the mating frame plates.
For me with only nine 0 n 0s out of a fleet around twenty six steam traction units, the rest all having those pesky carrying wheels and many being big long Pacifics and Prairies, I’m sure both approaches continue to have their place. Unfortunately I’m doubtful you share that view even to the point when, presumably carried away, you wrote that Bradwell’s Spring Plates were obsolescent in the post Csb world and should be deleted from the S4 stores!
As you say we are all prone to stick with what works for us. Csbs are your baby, Ted’s and Russ’s and you can rightly be proud of your collective contribution to helping many P4 modellers onwards and upwards towards “fine running”, in the spirit of the Scalefour Society's policy. Individual springing as invented by the Railway Mechanical Engineers has also contributed and I believe still provide our models with a simple and universal answer. I stick to that method not through unwillingness to innovate or abandon my baby but because it serves in EVERY case.
Chris P

[Will L]

Chris, I too once wondered about the suitability of CSBs for more complex wheel arrangements, at about the same time (quite a few years ago) that Russ made that remark. It was trying to sort out Bills 4-4-2 sprung C12 chassis that convinced me I could use a CSB for such things (if not quite how Bill conceived it) which gave rise to the posting i pointed you at. There may still be a few more esoteric wheel arrangements which would give me pause, but I think pretty general applicability is there, assuming your prepared to leave the occasional (particularly trailing) pony truck out of the equation. I remain unconvinced that to get best performance, all wheels carrying weight on the prototype must do so on our models, is necessarily true (though a perfectly sound modelling aim if that’s what “getting it all right” means to you). I readily admit if you really want to mount a Jackson Coupling onto a pony truck it will need to carry weight.

Your reference to your MRJ6 article caused me to dig it out and re read it. I must have read it when it first appeared, and although I don't actually remember it, I was surprised how closely, a some years later, my own thinking followed your line of thought. I may well have been unknowingly influenced by ideas it put into my mind. I never went down the rubber pads route although its predictability has attractions. I'd be interested to know how durable that solution proved to be.

I'm afraid I do tend to go on about the " lack of adjustability difference between CSB and individually sprung chassis ". This is because this lack of adjustability on a CSB has been used (wrongly I'm afraid) as an argument as to why CSB weren't a good way forward.

Nor can I accept that the tale of the heavy weight loco crew upsetting the balance of my O4 was a CSB failing. Once correctly adjusted I doubt very much there is any significant difference between the sensitivity to a misplaced CofG of a individually sprung or CSB based chassis. It was my own fault for not taking to heart my own guidance on CofG location care. Fitting two portly white metal figures well beyond the last axle of what was at the time a reactively light loco had a a significant influence on its CofG. It needed a surprisingly large chunk of led in the smokebox to correct it. If you start doing the maths on a 4 axle chassis with the CofG the wrong side of the 3rd axle you will soon see how easy it is to deprive the 1st axle of the necessary weight to hold it down. The point being that the warning I got about being careful about CofG placement was equally applicable to any properly sprung chassis

Just how sensitive CSB solutions are, or are not, to dimensional errors is another thing. Russ had this unfortunate habit of quoting fulcrum placements in mm to 2 places of decimals, strait off the spread sheet. I did manage to talk him out of that and you should note the spread sheet now defaults to rounding to an accuracy of 0.5mm (as that represents a reasonable level of accuracy for the average modeller measuring stuff with a steel rule). The resulting chassis have been found to work perfectly well, and you can turn the rounding off if you want. CSB would not have been acceptable if it wasn't robust enough to work with this level of tolerance. I do always advise against guessing fulcrum placements on any chassis with more than two axles because I don't think the result are that intuitive. That said I'm aware others do get away with it, showing the results are robust. None the less, handrail knobs with out of centre holes are best left in the scrap box where they belong.

Of course you won't want to switch methods now Chris, I understand that, but of those new to sprung chassis, I still think CSBs represent a significantly easier way of achieving the same result.

[Julian Roberts]

assuming your prepared to leave the occasional (particularly trailing) pony truck out of the equation. I remain unconvinced that to get best performance, all wheels carrying weight on the prototype must do so on our models, is necessarily true (though a perfectly sound modelling aim if that’s what “getting it all right” means to you). I readily admit if you really want to mount a Jackson Coupling onto a pony truck it will need to carry weight.
.

I've seen too many 0-6-2 locos with derailed pony trucks! - admittedly often occurring when working backwards, as well as other 2-×-0 locos similarly misbehaving. My single loco with carrying wheels*, a 2-6-0 Crab, hardly qualifies me to contribute much to your learned discussion, but experience with that suggested a lot of weight needed to be on the pony. With only its own weight the wheel didn't go round, for starters!! I loaded it until there were no derailments at full speed - the worse the track the more weight needed so it was track and speed dependent too.

I concluded that there is an inverse modelling problem - the more it weighed, the more wheels the prototype needed, while for us the more wheels there are, the more we have to work at finding weight to keep them all on the rails!

*excluding three 4-4-0 / 0-4-4's which all carry loco weight through a roller thus guiding the loco but with minimal resistance to the bogie swing.

[Will L]

assuming your prepared to leave the occasional (particularly trailing) pony truck out of the equation. I remain unconvinced that to get best performance, all wheels carrying weight on the prototype must do so on our models, is necessarily true (though a perfectly sound modelling aim if that’s what “getting it all right” means to you). I readily admit if you really want to mount a Jackson Coupling onto a pony truck it will need to carry weight.
.

I've seen too many 0-6-2 locos with derailed pony trucks! - admittedly often occurring when working backwards, as well as other 2-×-0 locos similarly misbehaving. My single loco with carrying wheels*, a 2-6-0 Crab, hardly qualifies me to contribute much to your learned discussion, but experience with that suggested a lot of weight needed to be on the pony. With only its own weight the wheel didn't go round, for starters!! I loaded it until there were no derailments at full speed - the worse the track the more weight needed so it was track and speed dependent too.

Another case when despite rabbiting on for far too long, I have failed to fully explain myself. Carrying wheels not taking body weight certainly do need to have sufficient weight of their own. I always weight such wheels quite significantly. To use body weight it must be arranged so its transmission is effective (positive or neutral effect on the chassis running properties) and in the proportion you want (sufficient to avoid derailments and keep the wheels turning), that is the tricky bit particularly with carrying wheels at both ends. I suspect that playing this game has made me a bit obsessive about knowing what weight is being transmitted where and why. Most of the rest of you seem to manage quite happily not knowing. I would argue that this not knowing is why many modellers have had the experience of finding that their latest pride and joy failed to live up to running expectations.

I concluded that there is an inverse modelling problem - the more it weighed, the more wheels the prototype needed, while for us the more wheels there are, the more we have to work at finding weight to keep them all on the rails!

Now there is an interesting way of looking at it. Thank you

[Chris Pendlenton]

Will appears to give a nod to my rule of thumb that a carrying axle should bear about half the weight as does a driving axle. Therefore a medium weight 2 6 0 or 0 6 2T of say about 350 gm should have the pony supporting about 50gm, the three driving axles 3 x 100gm. About the weight we like our wagons to be, but we struggle to attain. Very hard to get even a half of that weight onto an unsuspended truck in the space available, so the thing will skeddadle around in uncharted territory way below what a full size weight diagram would specify.
Maybe this is the wrong approach and that a free ride pony only needs so much weight (how much?) to hold it down regardless of what the engine weighs and on low speed layouts I’m sure this may be acceptable (where Jackson coupler mounting is not involved) but there are yaw forces at work above which friction plates bearing onto the frames may help to limit. From my observations yaw is a big factor in pony derailment particularly on long engines where, say, a Cartazzi truck being reversed can be pushed against its pivot to assume an exaggerated angle to the inner rail on a curve and look for the least excuse, like an imperfect rail joint or point blade seating, to break free. This it is more likely to do if laterally unrestrained and doing nothing to lead the engine into the curve and mitigate the yaw. Maybe that’s why Julian’s 0 6 2s misbehave.
Chris P

[Horsetan]

.....you wrote that Bradwell’s Spring Plates were obsolescent in the post Csb world and should be deleted from the S4 stores!
....

They've been long out of stock anyway, and nobody knows if a new batch will (ever) appear.

[davebradwell]

To be clear these are the springing units for locos that the Society sponsored years ago. The phototool no longer exists, anyway.

I have healthy stocks of the wagon spring plates.

DaveB

[Chris Pendlenton]

Good you dug out MRJ 6 Will. It was my attempt to show an alternative to compensation which Ian Rice, as the technical authority on the magazine, was promoting as a P4 standard. To answer your question I fairly quickly moved on from natural rubber pads as they began to deteriorate after about six months after prolonged exposure to oil. I replaced them with silicone rubber pads made by drilling 2mm holes in 1/16th brass plate and trowelling in the liquid silicone. When set I slice off the surplus with a razor and pop them out and into a small retaining cup soldered onto the top of the axlebox. The 10 ba stud screw set in the roof of the hornguides, with a rounded rather than pointed end, bears into the pad and is of course adjustable. I have several engines still using these and the pads are very long lasting though you would be quick to point out, not as long lasting as a csb wire- or in fact the single “leaf “ wire I moved on to. This has with hollow grub screw adjustment in one of a pair of foundations either side of the hornguides. This is how “Hal o’ the Wynd” is suspended as seen in the article in MRJ 28- your next read Will! This method is incorporated in all Dave Bradwell's kits, also his Spring Plates now unfortunately beyond resurrection it seems.
I ‘d just add that I was wrong about making coil springs. Dead easy it turned out to be using phosphor bronze 0.3 mm wire spun over a drill former as described in my article on the Deltic which has a lot of them.
So I now have three systems, pads in cups, coils and grub screw leaf springs. The first two still have their place in confined situations. I mainly use the second and third for very big heavy locos.

Ref your O4 I remain baffled that two metal figures, however portly, can be held responsible for a front driver lifting other than in a wildly, rather than slightly, unbalanced and too light engine! In all the many sprung engines I have built from 0 4 4Ts and 4 4 0s through eight coupled types to Moguls, Mikados and Pacifics, I have never had a similar experience though never identifying where the c of g was other than by general feel. The sensitivity of the exact location of the c of g, which you say to be vital to csbs, prompts thoughts about the interactivity between all wheels of the single continuous spring whereby as one wheel goes down its neighbour is lifted. But that's just equalisation? I recall raising this with Ted Scannell years ago but realised that my brain ran out of grasp. He cited the WD 2 8 0 tender as a sort of csb but I could only somewhat flippantly counter that on the big railway they were notoriously prone to derailment, as was a model LNER 8 wheel tender that was my only experiment with the system!
I am also thinking that for those who put motors inside the loco, driving on the middle axle, lead weight can only be added in the limited space above the motor. Logically the area forward of the motor can only continue with this limited weighting if the c of g is to be precisely placed above the drivers. So to preserve the criticality of the c o g position you end up with a lighter loco whose adhesion is less than it might be despite the “identical loading” of all drivers. Like you though my standard practice is to put motors in tenders to free up space in the engine for lead, but compact tank engines can't avoid the issue.

None of this is to imply that csbs are not a simple and valuable technique that finds widespread support amongst a probable majority of users. I would just repeat that both methods of springing are equally valid in particular circumstances and my continued use of individual springing is not down to habit but to suitability for the sorts of big engines I build.
It would be good to hear from users what have been their experiences.
Chris P

[petermeyer]

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

Returning to the original question and thanks Ian, and sorry for not having responded sooner. Your Bulldog looks impressive too. I did in fact sleeve the bogie pivot on my Finney Duke as you suggest for your second Bulldog build and my Duke runs OK so I will probably do the same with the City. That was the reason why I also had to widen the slot in the bogie.

As I alluded to earlier, this thread has made me revaluate some of my other 4-4-0's and I think I'll start another thread on my troubles with bogies rather than elongate this one further.