Bogies and buffers

[Andy W]

At a recent show I was told several P4 coaching stock "pearls of wisdom" which I've been pondering over. The first is that as long as one coach bogie can roll while the other can pitch, the individual bogies do not necessarily need compensating/springing. This goes against the principles I've always assumed to be set in stone. Is this just bunkum?

Secondly, someone else assured me that in P4 coaching stock MUST have sprung buffers. I can see this is logical and desirable. As a Midland man this is no problem thanks to Kean Maygib and several others suppliers. However, I've just finished several LBSCR; SECR and LSWR kits and all have white metal buffers. Does anyone know any suppliers of sprung versions for these companies? If not, surely trying to drill out the white metal to fit a sprung shank in - without machine tools - is a guaranteed way of ruining several sets of buffers?

Should I just accept solid buffers and finish the stock?

Thanks

Andy

[Will L]

At a recent show I was told several P4 coaching stock "pearls of wisdom" which I've been pondering over. The first is that as long as one coach bogie can roll while the other can pitch, the individual bogies do not necessarily need compensating/springing. This goes against the principles I've always assumed to be set in stone. Is this just bunkum?

Given the very short wheel base of bogies, rigid wheelbases work fine unless your track is really bad. Please note one bogie must rock side to side, but both must pitch front to back. Of the three rakes of CLC coaches running on Knutsford East, one has rigid bogies suspended in this way. When we first started running them, there was one rogue bogie that did give trouble. It's because they're not compensated said the non believers, but it turned out to be an esoteric build problem with the rocking bogie which stopped it pitching back and forth properly.

That said, I would now always use sprung (not compensated) bogies for preference. This is because the ride of the coach body just looks so much better when the bogies are sprung. For now, I would still stick to the pitch and roll rules, particularly if your track gaffer lays super elevated curves, but I haven't tried Bill Bedford's secondary suspension units yet, which are supposed to meet the roll requirement.

Secondly, someone else assured me that in P4 coaching stock MUST have sprung buffers. I can see this is logical and desirable. As a Midland man this is no problem thanks to Kean Maygib and several others suppliers. However, I've just finished several LBSCR; SECR and LSWR kits and all have white metal buffers. Does anyone know any suppliers of sprung versions for these companies? If not, surely trying to drill out the white metal to fit a sprung shank in - without machine tools - is a guaranteed way of ruining several sets of buffers?

Again, while sprung buffers are nice to have, I don't believe they are mandatory. Before you worry about springing the buffers, first of all make sure the buffers are correctly placed on the body ends vertically and horizontally (of course you will) and that the coach runs properly centred on the track (ah!). It is amazing how often, when you look along a rake of coaches or wagon from above, you realise that for one reason or another the centre lines of the vehicles just don't line up. That's when there being pulled, it can get a lot worse when the are being pushed because sloppy bearings will let the vehicle crab.

Then you need to worry about the coupling length. If it's too short for your minimum radius curves then something has to give. It may be that true scale couplings are impossible for smaller radius curves without sprung buffers, or if the radius is tight enough, not possible at all. But as they also make coupling even more maddeningly difficult than usual , a little exaggeration is often a better bet. Exaggerate enough and the buffers don't need to be sprung.

That said, stock buffering up just looks and reacts so much better with sprung buffers. So I always spring mine. Converting white metal or plastic buffers isn't half as hard as you seem to think. Only hand tools required.

Once the fixed head and shank have been cut off the buffer, it is necessary to drill a .5mm hole right through the buffer body and down the spigot at the back. The important bit is to start accurately in the middle of the cut off shank. So carefully centre pop the spot so the drill won't wonder before it starts to cut. After that it isn't actually necessary to drill perfectly through the exact centre all the way down, nobody will ever spot the difference.

It turns out it isn't all that difficult to drill the .5mm hole right through by hand with a drill in a pinchuck. You can do it holding the buffer body in your fingers, but an easier way is to hold the buffer body by the spigot in a second pinchuck and revolve the drill and the body in opposite directions. Its quite obvious if you are significantly out of line. If the buffer is already mounted in the buffer beam then even less accurate drilling will suffice but I wouldn't take inaccuracy too far.

If your not used to drilling .5mm holes with a drill in a pin chuck, you may need to practise a bit before you stop braking the drills.

Once you have the .5mm hole all the way through. Drill 1mm with the pin chuck again. This will follow the .5mm hole. Drill deep enough for the buffer head to just touch the buffer body with the spring fully compressed.
Time for one wagon less than half an hour, and a significant bit of that is threading the springs onto the buffer head. This needs much more manual dexterity than drilling the holes.

[grovenor-2685]

The first is that as long as one coach bogie can roll while the other can pitch, the individual bogies do not necessarily need compensating/springing.

There's no magic in any of this, no absolutes, it all depends.
If you have vertical curves in your track as at the top and bottom of any gradient then both bogies must pitch or wheels will be lifted off the track. For roll it is to be expected that track will have some degree of twist or cant (twist being unwanted cant) so one bogie needs to be able to roll with respect to the other, this can be achieved by allowing both some roll freedom with respect to the body which can result in wobble, or by keeping one bogie linked to the body resulting in an asymnetry in the ride, you take your choice.
This takes care of track irregularities with a wavelength of coach length. Irregularities of bogie length are usually much less and hence compensation or springing within the bogie may not be essential. A good guide will be to treat bogies in the same way you treat standard 4 wheel wagons. If rigid wagons are OK on your track then coach bogies will most likely be OK as well.

Secondly, someone else assured me that in P4 coaching stock MUST have sprung buffers.

As usual it all depends, are you going to shunt 2 or three coaches around on a plank or will you be running 10 coach trains at 60 mph?
Do you want your coaches to behave like loose coupled wagons or to move as a set as expected of screw coupled coaches. Solid buffers will enforce the former, sprung buffers with suitable couplings will allow the latter.
Regards
Keith

[John Bateson]

Keith,
I note you have not covered the case where buck-eye couplings are used. I have always assumed that bogies on such a rake must therefore have full pitch and roll capability since the buck-eye connection lock the carriage ends together.
In this case the buffers will I assume always be in the retracted position anyway.
John

[grovenor-2685]

I didn't think that Buckeyes were relevant to the question. But they don't lock the coaches together hard enough to stop one coach rocking with respect to the other. It can become an issue though with gangways if the presure is too high they can hold the ends together and cause problems, even derailments. I set mine to just touch and make sure the ends are smooth so they don't catch as they slide across each other.
See also http://www.scalefour.org/forum/viewtopic.php?f=24&t=627
Regards
Keith

[Wizard of the Moor]

One other point to consider with rigid buffers, is that they must be the same length.

I spent last weekend operating a layout at the Nottingham show and one wagon consistently derailed when being propelled over turnouts. After much examination of the track it was noticed that one buffer head was sticking out 2mm further than the other. When the longer buffer was on the inside of the curve, the pushing force lifted the wagon just enough for it to climb over the rail.

I suppose that this would also apply to sprung buffers if they bottomed out at different depths

Cheers,

James

[grovenor-2685]

When the longer buffer was on the inside of the curve, the pushing force lifted the wagon just enough for it to climb over the rail.

Interesting but logically a bit odd. When propelling round a curve with rigid buffers its only the buffers on the inside of the curve that are in contact if the buffers are the same length, so logically a slightly longer buffer on the inside should not matter. i suspect there may have been some other defect exacerbating things.
See also http://www.scalefour.org/forum/viewtopic.php?f=23&t=304#p1569
Regards
Keith

[Philbax]

Hi
My solution is to use sprung buffers and ideally if tpossible touching on straight track, you may need to have a gap if you have tight curves to negotiate, testing will tell.
Then I use the brassmasters lost wax coupling which looks really good, but only appropriate if you run your coaches in sets

rgds
Phil

[Terry Bendall]

On my son's layout Staverton we have a set of 8 Bachmann coaches with P4 wheels fitted directly into the existing bogies so no compensation of any sort but a bit of slack in the existing bogie mounting. They are fitted with KD couplings with the curved part that is underneath cut off to give a reasonable representation of a knuckle coupling. Screw couplings are fitted to the end vehicles. These run very well on indifferent track, over a 28 foot run at a moderate speed and some of the track is now 30 years old. Mind you they never get shunted which is another thing.

As Keith says there are no absolutes on this. If you can get a wagon, coach or locomotive to run without compensation then do so. It will save you time and effort and means that the layout will get finished sooner. Certainly there is no compensation on any of the diesel locomotives that we have and these do lots of shunting.

Appearance of the running is of course anotrher thing and it depends on what you want to achieve. Perhaps the appearance will be better but the old problem of not being able to scale nature - ie an exact scale weight of coach on exact scale thickness of springs, comes in.

Regards

Terry Bendall

[Andy W]

Thanks for all your replies and suggestions. All fascinating stuff. I think it highlights the fact that I need to work out why I'm building my stock in the first place! I've been ploughing on in splendid isolation.

It's good to know there are such knowledgeable members out there willing to help. I remember seeing a little doodle by (I think) Michelangelo, in which he is an old man being pushed along in a wheelchair. Underneath he wrote "Still learning."

I wonder if he was a P4 modeler?

[williambarter]

For the SECR and ex-SECR types in particular I have had trouble sourcing accurate sprung buffers. For bogie stock, the best I have come up with is to use Alan Gibson early coach buffers, but build up the base of the buffer casing from layers of etchings, which also serve to retain the Gibson buffer on the headstock.

For ex-SER 6- and 4-wheel stock, the right buffer casing has 3 ribs rather than the 4 that feature on most commercial whitemetal offerings. But John Arkell trading as Meadow Road Models has now produced an accurate buffer, which I have found very easy to drill out for springing. For coaching stock, it needs you to fabricate for yourself the wooden block on which the buffer casing was mounted, but that is not difficult.

William Barter

[jim s-w]

Hi All

As mentioned by others I use Buckeyed stock so for my buffers to touch would be wrong anyway!

Cheers

Jim

[martin goodall]

I have only just come across this thread, as I usually only look in "View active topics" when visitng this site.

I can't help feeling that we (or those of us still using wheels with the miscroscopic P4 flanges) have made a rod for our own backs, and that the need for compensation / springing, sprung buffers and all the other messing about stems almost entirely from the use of wheels with such impossibly small flanges.

Using EM-profile wheels set to P4 back-to-back, I have found that the need for compensating coaches, wagons and other stock entirely disappears. Nor do I find it necessary to spring buffers. I have added thin pieces of micro-rod to the rubbing plates of coach bogies, one mounted lengthwise and the other cross-wise, simply in order to prevent the unrealistic 'wobble' that can sometimes be detected when a bogie vehicle is in motion, but this is purely cosmetic and is not necessary in order to to keep the coach on the rails.

Having given a fair amout of thought to this topic, I have become increasingly convinced that all the fuss and bother about compensated suspension, etc. in the early writings of the P4 pioneers, which has been religiously intoned like a mantra ever since, stems solely from the adoption of dead-scale wheel flanges way back in the 1960s. It seems odd that the MRSG should have adopted such a fine flange profile when they were perefectly happy to compromise over flangeways and check rail celarances for the sake of 'practicality'. A similar compromise over the flange profile would have saved an awful lot of time and trouble for everyone.

And as we all know from bitter experience, with the very fine flanges in P4, all the compensation and springing in the world on track laid as flat as a billiard table won't prevent occasional derailments on a P4 layout. I see that some of our technical gurus have admitted sotto voce that maybe P4 flanges are a bit on the small side and that perhaps a slightly deeper wheel flange might have practical advantages. In the meantime, pending the eventual publication of a revised P4 wheel profile, I am happy to carry on using EM-profile wheels on my P4 layout.

[LesGros]

I have only just come across this thread, as I usually only look in "View active topics" when visitng this site.

I can't help feeling that we (or those of us still using wheels with the miscroscopic P4 flanges) have made a rod for our own backs,

What has this to do with bogies and Buffers ?

[TonyMont]

Hi All,
I know that Martin likes to wind us all up, and I suppose he has succeeded, but if he does not want to use P4 standards, why is he on this forum?

Best regards,

Tony.

[martin goodall]

In answer first to Les, what I wrote follows on from the other contributions on this thread. The point I am making is that the problems discussed on this thread stem largely from the use of P4 wheels with their tiny flanges. Use wheels with deeper flanges and you can largely forget about compensation or springing, sprung buffers, etc. etc. And don't under-estimate the modelling time you are spending (I was tempted to write 'wasting') in messing about with all this technical gubbins.

As regards Tony's question, I look for practical hints and tips on this forum, and there are quite a few to be found. But I am increasingly convinced that some aspects of P4 orthodoxy are leading people down blind alleys. If you enjoy that sort of thing, then that's fine, but if you want to produce one or more finished layouts in your lifetime and a reasonable quantity of rolling stock, then some of the more high falutin' aspects of finescale might be better avoided.

So the reason I am on this forum is to pursue (both as a reader and an occasional contributor) the practical aspects of model-making, rather than the theory, and to find quicker and more effective methods of producing finished models. If that involves departing from the strictest standards, for example by using EM wheels instead of P4 wheels on 18.83mm gauge track, then I am happy to do so. Pricking a few bubbles on the way is all part of the fun.

[Paul Willis]

Tony asked:

Hi All,
I know that Martin likes to wind us all up, and I suppose he has succeeded, but if he does not want to use P4 standards, why is he on this forum?

It's not often that I feel the urge to pull on my Deputy Chairman's cap (or flak jacket...) and post as such on the Forum. However I thought that I'd take a break from grinding point blades and make a couple of observations before any bricks, or worse, start flying.

(1) The primary objective of the Scalefour Society is to promote 4mm finescale modelling. If you look back as some of Martin's past work, and there is no better place than several editions of MRJ, then you'll see without doubt a highly skilled 4mm modeller.

(2) Although the Society publishes and promotes P4 standards, it is not a prerequisite for being a member. Indeed, we have many members that do Other Things, but appreciate the technical skills and like-minded individuals found in the Society, and I definitely would not want to discourage that.

(3) Much of what has been advanced by members of the Society in the last 40 years has been by pushing at boundaries, and perhaps Martin is doing that in a different way, stepping back from "perfection" in favour of practicality, but we should hear him out none the less.

(4) He's paid his subs, and has a right to post just as much as anyone else. Indeed, if he is currently modelling, then that's a lot more than I was doing for fifteen years or so of membership when I did nothing in P4 or any other scale/gauge.

Yes, of course Martin writes in a style that is baiting slightly. But there's no rule about doing that, or humour in any other way. Email can be a funny thing, and messages can often be taken the wrong way or ;-( as you see that...

So as long as he doesn't jump on *too* many threads with a proposal to take us to an EM standard(!), then let's all appreciate different points of view. Martin's is *an* approach to the question originally asked - just not the sort of one that was actually anticipated.

Yours with good wishes to all,
Paul Willis
Deputy Chairman

[Will L]

...Having given a fair amout of thought to this topic, I have become increasingly convinced that all the fuss and bother about compensated suspension, etc. in the early writings of the P4 pioneers, which has been religiously intoned like a mantra ever since, stems solely from the adoption of dead-scale wheel flanges way back in the 1960s.

and

I am increasingly convinced that some aspects of P4 orthodoxy are leading people down blind alleys. If you enjoy that sort of thing, then that's fine, but if you want to produce one or more finished layouts in your lifetime and a reasonable quantity of rolling stock, then some of the more high falutin' aspects of finescale might be better avoided.

Martin I fear you are assuming that your objectives are "the objectives". I suspect that, like me, our founding father would find your approach misses the point. They were coming more from the direction that having spent many hours getting other parts of the model as close to scale as possible they didn't want to going sticking on out of scale flanges on wheels the wrong distance apart. If they had stared from wanting big layouts with lots of stock I doubt they would have bothered with anything fancier than EM, which is pretty much were you seem to be, give or take 0.63 mm. Not that there's anything wrong with that, I would defend your right etc., just as long as you don't expect me to join you.

Also speaking as one who currently operates a P4 layout at exhibition and in a previous existence spent many hours behind an an 00 layout, I think it only proper to point out that to get the level of performance demanded out of the 00 stock much of it was compensated, and buffers were sprung. In practice both layouts ran equally well but this was because troublesome stock was not tolerated, each failure being diagnosed and the cause corrected. If one is not prepared to do this no layout will produce quality good running, and the running on some 00 layout you see does leave much to be desired!

Examples, what ever you standards. Rigid loco chassis often perform poorly because three points of contact with the track is not enough for good electrical contact. Uncompensated coaches fall off on super elevated corners. Buffer locking on freight stock is often down to the vehicles crabbing because of excess slop in the wheel bearings.

Will

[martin goodall]

I think Will is right in suggesting that the MRSG (the founders of P4) were thinking in terms of getting as close to scale as possible and were attempting to apply that approach to wheels and track as well as the other parts of their models. In doing so, they gave themselves some practical problems relating to the performance of rolling stock, because although the track gauge, flangeway clearances, etc. in P4 are all perfectly practical (largely by reason of their involving some dimensional compromises compared with a ‘dead-scale’ approach), it was their choice of an almost dead-scale wheel flange that made it necessary to pay much closer attention to the riding characteristics of wheels, leading them to resort to compensated suspension or springing in an effort to keep their much finer profile wheels on the track.

Having compromised over flangeway clearances, etc, it is rather surprising (especially in light of subsequent experience) that the MRSG did not make a similarly modest compromise over the flange profile of the wheels. Had they done so, we would not be having this discussion, and the performance of bogies and the need or desirability of springing buffers would not be an issue for us.

As a result of my own experience, as well as observing the results achieved by friends working in P4, I think I can confirm with reasonable confidence that compensation or springing of bogies is not necessary even if you adhere strictly to P4 standards, provided you mount the bogies so that one can tilt sideways and the other can tilt fore and aft. Some slop in the bearings may also help if the bogies are neither compensated nor sprung. Mounting the bogies in the manner mentioned above is something I would recommend in any scale or gauge, with or without any fancier suspension arrangements.

Hunting (or crabbing) of wagons is a problem in all the 4mm gauges (00, EM and even P4, if you stick to the orthodox P4 settings). The only way of eliminating it entirely in 18.83mm gauge is to adopt Ray Hammond’s “Scale Four” standards, or to use EM wheels as I do. There is then no risk of buffer locking, and no need to use sprung buffers.

Finally, as regards rigid loco chassis, I have seen a couple of 00 layouts at exhibitions recently (both built and operated by the same owner) which ran impeccably. The locos were sure-footed and reliable, could be slowed to a crawl and did not stall or stutter anywhere on the layout. It turned out that they had rigid chassis, but plenty of weight to keep all the wheels firmly on the rails. (I assume there must have been a modicum of slop in the bearings.) Turnouts had live crossing vees, and this ensured electrical continuity through the crossings. I have a Bachmann Collett Goods, converted using an Ultrascale conversion pack (and still with P4 wheels, which have not yet been changed for EM wheels), which performs very sweetly on my own layout, despite having an entirely unmodified rigid RTR chassis. In EM gauge, Roy Jackson has always advocated rigid chassis, and so it may be worth reconsidering the use of rigid chassis, even in P4.

[jim s-w]

Bit OT aint it?

Cheers

Jim

[grovenor-2685]

There is a topic covering wheel and rail profiles here, http://www.scalefour.org/forum/viewtopic.php?f=64&t=532, best place to discuss this issue.

Keith

[martin goodall]

Although this particular discussion was about bogies and buffers, it seemed relevant to discuss precisely why (as well as whether) bogies need to be compensated or sprung and why buffers might need to be sprung. The underlying reasons which make these devices necessary or desirable in P4 cannot be overlooked, and inevitably bring us back to a consideration of track and, in particular, wheel standards - because this is what gives rise to the need for compensation and/or springing. I did refer passim to both bogies and buffers, as that was obviously the starting point of the discussion, but it would be artifical (and not altogether enlightening) to restrict discussion solely to that topic when it is clearly influenced by other factors.

[jim s-w]

The underlying reasons which make these devices necessary or desirable in P4 cannot be overlooked

Hi Martin

Based on practical experience I agree that sprung buffers and bogies are desirable. However that are certainly not necessary. Look at it this way, just how bad does track have to be for an 8ft 6 bogie (that if its a converted RTR plastic one - and therefor not that rigid anyway) to derail. I regularly run RTR coaches with rewheeled bogies over some pretty dire track without any problems.

Cheers

Jim