Suspension for bogie coaches

bordercollie
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Suspension for bogie coaches

Postby bordercollie » Wed Jun 24, 2020 2:17 pm

Hi
I have just ordered some bogie coach kits which I will need to supply with some sort of suspension. What is considered to be the best solution, compensation or CSB? Or is it a matter of preference? Is there a reference somewhere that compares the pros and cons of each type?
Thanks

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Tim V
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Re: Suspension for bogie coaches

Postby Tim V » Wed Jun 24, 2020 3:06 pm

Actually, not necessarily.

A lot of my coaches were running on original Bachman/Mainline type bogies, with no alterations. But they did have very good wheels.
Tim V
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bécasse
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Re: Suspension for bogie coaches

Postby bécasse » Wed Jun 24, 2020 3:20 pm

One bogie needs to be able to rock up and down along an orthogonal axis to the carriage length, the other bogie needs to be able to rock in any direction - thus effectively giving the carriage "three-point suspension". I am not convinced that any compensation or springing is needed within the individual bogies although I have, in the past, used a thin phosphor-bronze plate to mount all the various components of a bogie, thus inherently incorporating some limited flexibility, and that worked well.

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David Thorpe
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Re: Suspension for bogie coaches

Postby David Thorpe » Wed Jun 24, 2020 3:48 pm

Do your kits not include bogies?

DT

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steamraiser
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Re: Suspension for bogie coaches

Postby steamraiser » Wed Jun 24, 2020 5:43 pm

As Tim V says possible not needed.
But if you do then you have a choice of the Societies bogies (If still available), MJT, Bill Bedford and Rumney Models.

Gordon A

davebradwell
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Re: Suspension for bogie coaches

Postby davebradwell » Wed Jun 24, 2020 6:43 pm

Well, the Forum's been quiet for a while so a good old suspension question should liven it up.

Here's how it is: a sprung vehicle will always run quieter than a compensated one, although the nature of the springing may just be the resilience of plastic bogies or indeed flexible compensating beams so the statement covers a broad spectrum. The challenge with coaches is propelling a lot of them while the gangways remain touching and you'll need pretty good suspension for that. Secondary only springing (between bogie and body) is very effective and a simple scheme for Bachmann Mk1s, which could be used elsewhere, was described by Chris Pendlenton in MRJ200. Done well, secondary suspension should average out track bumps and wobbly wheels giving the body a smoother ride.

Just to be pedantic, a csb isn't the only type of spring.

Your choice won't be straightforward as everyone has their preference and any given type can be wrecked by poor implementation. Perhaps see also the thread on coach secondary springing before we start repeating it.

....and so much for your comprehensive list of bogies - I would normally offer a range but have been unable to re-stock. I think mine were the first sprung type. I said it would liven up.

DaveB

Rdunning
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Re: Suspension for bogie coaches

Postby Rdunning » Wed Jun 24, 2020 7:51 pm

Let's not overlook the twin torsion bar adaptation of the MJT bogie developed by Dick Petter and described in S4News no 184.

9'0", 8'6" and 6'4" wheelbase complete bogie kits are available from Palatine Models and the Society Stores, for other wheelbases the adapter kits are sold by the same suppliers and the original MJT bogies can be had from Dart Castings or the Stores (except for 8'0" wheelbase versions which seem to be permanently out of stock at both).

As far as I'm concerned they're the bees knees, relatively simple, effective and reliable in operation. Nearly all my bogie vehicles run on these now, I think you should take a serious look at this option.

Richard

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Noel
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Re: Suspension for bogie coaches

Postby Noel » Wed Jun 24, 2020 8:29 pm

No suggestions, just questions, the answers to which will affect how you build the kits: what sort of coaches; what is their length; what is the bogie wheelbase; are they corridor or non-corridor; what is the minimum radius you will expect them to negotiate; what sort of couplings do you use; are there any significant gradients where they will run; will they just go round and round a continuous run behind a loco, or do you want them to be propelled across complex pointwork, or something inbetween?

Everyone has their preferred options, but these are commonly informed by what they want the vehicles to do.
Regards
Noel

bordercollie
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Re: Suspension for bogie coaches

Postby bordercollie » Thu Jun 25, 2020 10:37 am

Thanks
In regards to Dave. It is an Broad Gauge Society kit. Therefore I assume that bogies are included. However, my ignorance is such that I don't know if suspension can be added to these bogies in some way or if I need to buy special bogies for this purpose.
The answers to the questions raised by Noel are: It is a GWR diagram E17/18 coach. It has 6'4" bogies with a 36' wheelbase. It is non-gangwayed. Minimum radius including turnouts will be 1.2m. Mostly engine pulling coach but some pushing eg pushing into carriage siding. No gradients involved. The most complex trackwork will be a cross over on a curve with minimum radius of 1.2m.
There seems to be an opinion that suspension isn't required. If it is possible to get reliable running without suspension of some kind then I don't want make things any more complex than is needed.
Regards

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Noel
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Re: Suspension for bogie coaches

Postby Noel » Thu Jun 25, 2020 11:59 am

if you check the BGS website entry for this kit http://www.broadgauge.org.uk/modelling/bgs_parts_prices_4mm.html item F4009, it has a small "i" in a blue circle in the description. If you click on that, you will get a PDF with instructions on building the kit. The bogies include rocking axles.
Regards
Noel

Philip Hall
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Re: Suspension for bogie coaches

Postby Philip Hall » Thu Jun 25, 2020 4:28 pm

If the wheelbase of the bogie is 6ft only then I reckon you really don't need any suspension at all. I would just build them all rigid, try them out on the layout and see if anything falls off. If it does, try the three point mounting idea.

I have converted many Hornby 8ft wheelbase bogies (true, these are a slightly flexible plastic, but not much) and for the first two made up the three point idea with pads supporting one bogie at each side. They ran beautifully. Then I converted a couple of bogie Van 'B's and left off the extra pads to see if it made any difference. They ran just as well with no problems! I should say that all these have absolutely concentric wheels (Ultrascale) and weigh about 190g each; the train was also coupled buffer to buffer including the engine. The test was not on a small end to end, but the Epsom Club's 'Wadhurst', a pretty large tail chaser and we were sprinting around at a scale 50-60mph. Seemed to me a good test, especially over some complicated pointwork in the fiddle yards.

Philip

bordercollie
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Re: Suspension for bogie coaches

Postby bordercollie » Fri Jun 26, 2020 5:39 am

Thanks all
I did press the i button for one of the 6 wheelers and there was hardly any information so didn't press the button for the E17/18. As you say there is a lot of information on the kit's construction.
I will be purchasing further kits as I build up a selection of coaches up to 1929. These will almost certaintly have longer bogies. If any kit does not include any type of suspension and if I subsequently decide that I do want suspension is it possible to retro fit? Please excuse me if this is a silly question.

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zebedeesknees
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Re: Suspension for bogie coaches

Postby zebedeesknees » Fri Jun 26, 2020 9:56 am

bordercollie wrote: If any kit does not include any type of suspension and if I subsequently decide that I do want suspension is it possible to retro fit? Please excuse me if this is a silly question.


Not silly at all, but a lot of work if the kit designer hasn't helped in that respect.

My take is that the real thing had springs between the axleboxes and the bogie frame, and between the bogie frames and the body. If you cannot, or do not want to see the difference, then why bother? Personally, I find the difference worth the extra work.

Ted.

"........... Believe nothing..............
unless it agrees with your own reason"

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David Thorpe
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Re: Suspension for bogie coaches

Postby David Thorpe » Fri Jun 26, 2020 3:52 pm

In the P4 world we do like to over-complicate matters where possible, not always with the desired results (I speak for myself there of course). You've bought a kit with bogies which the designer presumably thought would be suitable and you've no reason as things stand to doubt that. Why not just build the bogies as supplied and see if they work to your satisfaction? If they do, great, and you haven't had to pay out any extra money. If they don't, well then you may have to consider a replacement or a modification, but I bet that they'll be fine.

As for retro fitting of a different springing system, I suspect that would be more difficult than building a new bogie, and might well not be so successful

DT

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jon price
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Re: Suspension for bogie coaches

Postby jon price » Fri Jun 26, 2020 4:18 pm

Well to be picky, spings are not enough. You need springing dampers, and radial steering as well.
Connah's Quay Workshop threads: viewforum.php?f=125

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Guy Rixon
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Re: Suspension for bogie coaches

Postby Guy Rixon » Fri Jun 26, 2020 5:00 pm

zebedeesknees wrote:My take is that the real thing had springs between the axleboxes and the bogie frame, and between the bogie frames and the body. If you cannot, or do not want to see the difference, then why bother? Personally, I find the difference worth the extra work.


Some real things do not have the springs between the axleboxes and bogies. Apparently, American freight cars often have no primary springs, with the axleboxes free-falling in their guides and the secondary suspension doing all the work. I presume that the weight distribution between wheels in a bogie is not very uniform but the designers are OK with that.

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Guy Rixon
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Re: Suspension for bogie coaches

Postby Guy Rixon » Fri Jun 26, 2020 5:08 pm

bordercollie wrote:If any kit does not include any type of suspension and if I subsequently decide that I do want suspension is it possible to retro fit? Please excuse me if this is a silly question.


If you might want later to fit springs between bogie and body, you need enough vertical space for a little movement. Solid bogie mounts, or the kind that allow the bogies to rock about their centre pivot, don't provide this. Therefore, you might consider reducing the height of the fixed supports and packing with some kind of washer that could be later removed.

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grovenor-2685
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Re: Suspension for bogie coaches

Postby grovenor-2685 » Fri Jun 26, 2020 7:50 pm

Guy Rixon wrote:Some real things do not have the springs between the axleboxes and bogies. Apparently, American freight cars often have no primary springs, with the axleboxes free-falling in their guides and the secondary suspension doing all the work. I presume that the weight distribution between wheels in a bogie is not very uniform but the designers are OK with that.

The vast majority of freight bogies in the UK were similar to the american ones except in recent years when we have flirted with French and German designs. In general the weight distribution between wheels on these bogies should be good as they are equalised designs. Its not really possible to describe the springing on equalised freight bogies as primary or secondary since there is only one set! The axleboxes are not freefalling in guides, they are fixed to the sideframes with the springs between sideframe and bolster. Normally the bogies can be lifted as a whole but there are some designs purely held together by gravity. When there is a derailment bits go everywhere.
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Keith
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Flymo748
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Re: Suspension for bogie coaches

Postby Flymo748 » Sat Jun 27, 2020 6:49 am

grovenor-2685 wrote:
Guy Rixon wrote:Some real things do not have the springs between the axleboxes and bogies. Apparently, American freight cars often have no primary springs, with the axleboxes free-falling in their guides and the secondary suspension doing all the work. I presume that the weight distribution between wheels in a bogie is not very uniform but the designers are OK with that.

The axleboxes are not freefalling in guides, they are fixed to the sideframes with the springs between sideframe and bolster. Normally the bogies can be lifted as a whole but there are some designs purely held together by gravity. When there is a derailment bits go everywhere.


That sounds exactly like some P4 models I've handled whilst they've been displayed on the Society Stand at exhibitions! My apologies to any of the unfortunate members that I have done this to...

Axle keeps - just say "yes"!

Cheers
Paul
Beware of Trains - occasional modelling in progress!
www.5522models.co.uk

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Paul Townsend
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Re: Suspension for bogie coaches

Postby Paul Townsend » Mon Jun 29, 2020 3:50 am

I come late to this party as I have only just realised that the OP's query started with reference to a kit marketed by Broad Gauge Society for which I am the 4mm Trade Officer.

Noel spotted this sooner and correctly explained that this particular kit has rocking axle suspension in the bogies.

Just for the record:

The E17/E18 kit F4009 was only one of two bogie coaches in the range originally sold by IKB Models. Most of this range are BG/NG 4 and 6 wheel convertible Dean designs but this kit is supplied as the NG version.

The K2 F4008 is the other bogie carriage in the ex-IKB range which can be built as BG K1 with a few added parts. It includes a different design of Dean 6'4" bogie which has sprung suspension. These sprung bogies are used in other carriages in the BGS range which were not part of the IKB range, and can be built as NG or BG.

peterbkloss
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Re: Suspension for bogie coaches

Postby peterbkloss » Fri Jul 03, 2020 6:52 pm

Hi Everyone, just looked at this thread and asking those of you that have used MJT torsion bar bogies to comment:

1. Do you have problems getting the 'trunnion' that carries the bottom press stud 'square'? I seem to find it all too easy to have this tipped a bit so the coach looks permanently drunk - or is it that I am careless when doing the folds?

2. Do you find that your bogie isn't 'floppy' enough, i.e. the torsion bar is too stiff, and the wheels don't drop into dipped track as (i think) a compensated bogie should? sub points to this:

a. Is it necessary to solder the torsion bar to the 'trunnion' that the lower press stud fits? I find leaving this joint out makes the bogie rock more easily even if its a little harder to connect the press studs ...

b. Does the double torsion bar adaptation make this whole thing work much better?

3. Do you find it difficult to keep solder out of the press stud working bits (i.e. the little spring inside) - is there an optimal solder / flux to use as i find the things really difficult to get a good joint on?

4. In general do you find the press studs too stiff rotationally. Should I be oiling them?

In short, I'm finding the MJT bogies I've made up run no better than RTR bogies from Airfix, Mainline and Bachmann or even Hornby (Hawkesworth) on my indifferent 20+ year old track work.

I'd really appreciate your comments

Thanks, Peter Kloss

Paul Cram
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Re: Suspension for bogie coaches

Postby Paul Cram » Fri Jul 03, 2020 10:09 pm

I have a number of coaches using this system. I don't solder the torsion bar anywhere other than the ends. I haven't had a problem soldering the pivots square and the ones I have used aren't stoppping the bogie rotating freely. Most have Gresley whitemetal sideframes which helps nut I have some on some D&S North Eastern Coaches and they work just as well.
I use phosphoric acid flux and 145 solder. How heavy are your coaches?

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Will L
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Re: Suspension for bogie coaches

Postby Will L » Sat Jul 04, 2020 12:05 am

While a good concept, there are a couple of problems with the basic MJT bogies.

Firstly the is a flaw in the design which puts too much strain on the solder joints on the single torsion link. They certainly run OK to start with but they start breaking if you actually run them very much. Palatine Models offers an add on unit which overcomes the problem and also now does bogie kits that has the fix built in from the start. Look under 4mm products.

Secondly the use of press studs to fix them to the coach. A nice idea but nobody told the manufactures of press studs we would like to reliably find studs with consistent dimensions. You can't. So if you have a fleet of coaches which have apparently identical bogies you will find they aren't interchangeable. This may not bother some people but it generally does bother people who are thinking they are fitting a fleet with the same bogies.

peterbkloss
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Re: Suspension for bogie coaches

Postby peterbkloss » Tue Jul 07, 2020 9:55 pm

Thank you Will and Paul for your comments. To Paul, I was aiming at 100g per 4 wheel coach, as I thought that was kind of recommended, but I'm thinking that they need to be heavier.

To Will: I'll be looking at the twin torsion bar solution. I have read the articles and will try the upgrade ... and thanks for your comments about press studs, I'm going to experiment replacing them ...

petermeyer
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Re: Suspension for bogie coaches

Postby petermeyer » Wed Jul 08, 2020 5:55 am

No mention has been made of the Brassmasters torsion bogie which I started to use as there is no 6' 4" bogie in the MJT range. Having had no problems with them, I have since used them exclusively but do have a twin torsion from the Society to try when I get round to it.


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