Loco Suspension, fitting CSBs

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Will L
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Loco Suspension, fitting CSBs

Postby Will L » Sun Jul 18, 2010 11:37 pm

Anybody who’s been on here for a while will know that when it comes to any discussion about loco chassis and their suspension, I keep on suggesting that CSB’s (Continuous Springy Beams) are the way to go. That's all very well and good, people say, but until somebody explains exactly how your supposed to go about building a CSB chassis they are wary of trying it for themselves.

Well, as I’ve just started to set about converting an existing J10 from 00 to P4, hopefully for use on the Crewe area group layout Knutsford East, and I plan to use CSB’s under both Loco and tender, perhaps this is the ideal opportunity to do a blow by blow account.

One word of warning right from the start, I am not noticeably a quick worker and I tend to stop work while I’m thinking out how I intend to tackle the next problem. On top of that, committing to writing it up as I go along will tend to slow me down, particularly if I am to avoid making too big a fool of myself in public. So this may be a very occasional series, with entries being quite widely spaced in time.

One way that you can help is by feeding back opinions and asking questions, because assuming the feedback is helpful and positive, it will tend to feed my enthusiasm and goad me into making more progress.

Ok so that’s what I have in mind. My apologies to those who's interests are primarily with what was once laughably referred to as modern image, my tastes don’t run to loco’s with bogies, but the failing is mine not yours. I understand CSB’s can be applied to such things, but I won’t be going there. Anyway, before we get to the J10, I will firstly go over some why and what questions relating to CSB’s, and illustrate some previous experience.

Will

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Flymo748
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Re: Loco Suspension, fitting CSBs

Postby Flymo748 » Mon Jul 19, 2010 4:30 am

Will L wrote:Well, as I’ve just started to set about converting an existing J10 from 00 to P4, hopefully for use on the Crewe area group layout Knutsford East, and I plan to use CSB’s under both Loco and tender, perhaps this is the ideal opportunity to do a blow by blow account.


Thanks Will. As I'm just coming to the end of building my first CSB locomotive, using High Level hornblocks, and an initial plot and some guidance from Ted and Russ from CLAG, then I'll be very interested what you might do differently, and what the same.

Here's a taster picture...

CSB 012.jpg


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David Thorpe
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Re: Loco Suspension, fitting CSBs

Postby David Thorpe » Mon Jul 19, 2010 6:39 am

Thanks, Will - just what I've been looking for. I'm really looking forward to this.

DT

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Will L
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Loco Suspension, Why and How

Postby Will L » Mon Jul 19, 2010 10:17 pm

First, why do we need suspension on our loco’s at all?

There is a fair degree of acceptance that, for P4 modellers, there is a need for some form of loco suspension as an insurance against derailments, allowing the locos wheels to follow any minor irregularities in the track. Despite this, a few sainted modellers are apparently able to produce track so well laid and flat that suspension is not necessary. There is also a suggestion that you can overcome the problem by redefining EM standards to include an 18.83 track gauge, which misses the point if you ask me, but then perhaps you didn’t.

I would argue that, even if a rigid chassis will reliably stay on the track, its performance in terms of electrical pick up and adhesion are compromised, as you can only rely on three points of contact between rail and wheels, no matter how perfect the track. It is for this reason that I started fitting compensation to OO locos long years ago when Mr Sharman’s Flexi Chassis thinking was state of the art.

Having accepted the need for loco suspension, what’s wrong with compensation?

Compensation is well understood now, and yes it does work. I would accept that it is certainly a lot better than nothing, even though some common wheel configurations (e.g. 4-4-0’s) can throw up unexpected difficulties. My major problem is with the single rigid axle common to all the simple implementations. The presence of this fixed axel means that the ride of the body reflects all the irregularities in the track, and these days I find this rather off putting. With more complex setups, where the single fixed axel is eliminated, the running qualities of the loco can be excellent. But the operative term here is complex, especially as the number of axles goes up.

And springing?

Springing your loco isn't just to keep the loco on the track, or to ensure good pick up and adhesion. It also isolates the body from the shocks transmitted from the wheels when they pass over track defects, or just ordinary point work. This is surely the real reason we a driven to fitting springs to our loco's. It's the jerky ride of the loco body on the rigid chassis, or on the compensated chassis with a fixed axle, which makes it so obvious you're watching a model.

Most springing systems produce locos with one spring per wheel. When correctly set up such a loco will run very well, but this performance is depended on getting the rating, or springiness, right for each and every spring/wheel. How you achieve the correct adjustment of each spring is the problem.

One “solution” for this is to have the springs so soft that they are fully compressed by the weight of the body which rides on a rigid stop. The Gibson system is of this sort. In this mode, the springs are there to push the wheels down into any low points in the track. The chassis has to lift the body over any high points, and therefore shares the same defect as a compensated loco with one rigid axle, only more so as it effects at least one more axles.

If you have overly hard springs, you will not only loose much of the isolation from track shocks, but when it comes to road holding, pick up and adhesion, your chassis will tend to behave no better than if it was rigid. So we are back to the need to get each spring's rating adjusted just right. There are those with the methods and skills to achieve this, but the ability to individually adjust each spring causes complexity. Those that can achieve this have my undying respect, but I think there is an easier way, and that is CSBs.

If you want a much longer and more detailed discussion of compensated and/or sprung chassis, see the Scalefour Digest 41.0 "The Principles of Model Locomotive Suspension" authored by Rus Elliott. A web copy is hosted on the CLAG web site, here, or you can down load it from the digest area of the Scalefour web site, here. This is a very interesting, if rather technical, document and I found it well worth a read. I understand it pre-dates the development of a significant interest in CSBs, and, although it covers the basics, it specifically excludes detailed discussion of the way they effect weight distribution, on the grounds of the complexity of calculating their effect.

Well we’ll see.

Will

P.S. Twice above I have referred to the fact that others espouse methods which I rate as too hard to bother with. As a general rule I find it better to accept that no matter how cack handed, difficult, or unlikely a method appears to me to be, there is always somebody who manages to make it work perfectly. Humility is the only answer.

P.P.S. We will get to CSBs shortly, I promise, and there may even be some pictures!
Last edited by Will L on Thu Jul 22, 2010 4:11 pm, edited 1 time in total.

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Russ Elliott
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Re: Loco Suspension, Why and How

Postby Russ Elliott » Mon Jul 19, 2010 11:16 pm

Will - the Brassmaster spring is not of the 'spring-assisted, soft' type. It is actually comparatively strong, in the region of 70g/mm, and therefore arguably a bit too strong for smaller, lighter locos. It was designed by Alistair Rolfe I understand, and I'm not aware Brassmasters have changed the spring since its introduction c 2003.

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Stephen F
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Re: Loco Suspension, fitting CSBs

Postby Stephen F » Tue Jul 20, 2010 10:08 am

Super, thanks for this thread, Will.
My first question is: whether or not CSB can be compatible with Brassmasters blocks, considering they locate in the frame and therefore fixing handrail knobs would be difficult. I imagine it becomes a question of friction if the spring wire is out of line with the axle movement.
Don't mean to jump the gun here btw, do put off answering till you get to it in your account.
Steve

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John Bateson
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Re: Loco Suspension, fitting CSBs

Postby John Bateson » Tue Jul 20, 2010 3:37 pm

Brassmasters hornblocks - how to fit CSBs.
Short length of brass tube soldered horizontally at the top and at the rear?
Small 1mmx1mm 'L' section with a hole in one side to suit the spring wire, again soldered at the top and rear of the hornblock?
Two longer 1mmx1mm 'L' section soldered at each side and rear of the hornblock?

Any ideas 'cos I need to know soonish ...

John

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Jol Wilkinson
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Re: Loco Suspension, fitting CSBs

Postby Jol Wilkinson » Tue Jul 20, 2010 6:47 pm

The LRM CSB adaptors are designed to fit onto hornblock bearings with a 4.0mm OD spigot i.e the LRM version. They could be sodered onto "plain" bearings i.e. no spigot but I don't know if they would provide exactly what you need as the offset of the spring beam locating ear may be wrong. Take a look at http://www.scalefour.org.uk/londonroad/ ... daptor.pdf

Jol

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Re: Loco Suspension, fitting CSBs

Postby allanferguson » Tue Jul 20, 2010 11:17 pm

I'm just into building my first CSB loco (a CR 4-4-0) I've used Brassmasters hornblocks, with old fashioned handrail knobs in holes drilled in the bearings. the lateral displacement is only 0.3mm (per Brassmasters drawing) and it seems to work OK. We'll see when there's a loco body on top!
DSCF0002.JPG

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Will L
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Re: Loco Suspension, fitting CSBs

Postby Will L » Thu Jul 22, 2010 4:02 pm

Way to go Guy's, with lots of active feed back we should generate a very useful knowledge base, as we used to say at work before I left to spend more time with my family. I certainly don't believe I have all the answers so adding everybody else's experience is all good input.

Looking at the last crop of responses:-
Russ Elliott wrote:Will - the Brassmaster spring is not of the 'spring-assisted, soft' type. It is actually comparatively strong, in the region of 70g/mm, and therefore arguably a bit too strong for smaller, lighter locos. It was designed by Alistair Rolfe I understand, and I'm not aware Brassmasters have changed the spring since its introduction c 2003.


I stand corrected and I will suitably amend the original posting. Reading your link, it would seem that to be successful with these you are required to adjust the weight to suit the spring rather than vice versa. Getting ride hight right will depend on getting the correct weight per axle. Useful things to know when trying to use them. Presumably an overweight enough loco would still revert to spring assist mode, but at 1Kg for a six wheel loco this isn't going to be that easy to achieve. I can also see why you have reservations about small light prototypes.

Stephen F wrote:My first question is: whether or not CSB can be compatible with Brassmasters blocks, considering they locate in the frame and therefore fixing handrail knobs would be difficult. I imagine it becomes a question of friction if the spring wire is out of line with the axle movement.


Well I didn't need to answer that one as along came

allanferguson wrote:I'm just into building my first CSB loco (a CR 4-4-0) I've used Brassmasters hornblocks, with old fashioned handrail knobs in holes drilled in the bearings. the lateral displacement is only 0.3mm (per Brassmasters drawing) and it seems to work OK. We'll see when there's a loco body on top!


Looks OK to me. My experience is that a little lateral displacement between the horn blocks and fulcrum points is not an issue, but prudence suggest you wouldn't want to overdo this. I would want to check that the tray like frame spacer wasn't restricting the downward displacement of the wire. (Just like stocks and shares wheels go down as well as up!). I'd be interested to know how the suspension on the bogey is arranged. This is a topic I will be coming back to, with as many questions as answers

Also on the subject of Brassmaster horn bocks

John Bateson wrote:Brassmasters hornblocks - how to fit CSBs.
Short length of brass tube soldered horizontally at the top and at the rear?
Small 1mmx1mm 'L' section with a hole in one side to suit the spring wire, again soldered at the top and rear of the hornblock?
Two longer 1mmx1mm 'L' section soldered at each side and rear of the hornblock?


Handrail knobs may be traditional John, and Alan has shown us how its done, but so long as you can reliably fit the suspension point a consistent and known distance from the axle centre line, then I don't see a problem, and as Jol pointed out there are commercially available components.
Last edited by Will L on Fri Jul 23, 2010 9:33 am, edited 1 time in total.

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Stephen F
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Re: Loco Suspension, fitting CSBs

Postby Stephen F » Thu Jul 22, 2010 8:26 pm

Looks good to me too, Allan, please let us know how it turns out. I suppose if necessary the handrail knobs could be filed down so they went right in up to their necks, as it were, but .3mm offset is pretty good going already.

Steve

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Flymo748
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Re: Loco Suspension, fitting CSBs

Postby Flymo748 » Thu Jul 22, 2010 8:44 pm

Stephen F wrote:Looks good to me too, Allan, please let us know how it turns out. I suppose if necessary the handrail knobs could be filed down so they went right in up to their necks, as it


What I have used on the J15 is the Alan Gibson "shoulderless" handrail knobs, so that you can put them in as deeply or shallowly as you like.

In my case, they were only needed for the frames, as I used the High Level hornblocks that have really neat mountings for the wires on them. I drilled holes for them through the frames, soldered the handrail knobs in place at the appropriate depth, and then cut/filed off the protruding part.

Sorry, no photos, as I didn't document the build of this locomotive as I went along.

HTH
Flymo
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Mike Garwood
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Re: Loco Suspension, fitting CSBs

Postby Mike Garwood » Thu Jul 22, 2010 11:22 pm

I'm really glad someone's taking this particular bull by the horns..I've now got all the bits I need to build my fourth 9f and who knows this one might even run! The other three chassis have been consigned to 'resurrect on a rainy day' draw! The question that I have is...
I'm using Gibson frames. Where does the centre of the horn block get measured form to give you the correct starting place, so that you get the correct ride height. I've looked at the CLAG site - thanks Russ loads of vital info there for the uninitiated - but I still don't understand where to start. Is it pot luck? - probably not. Middle of the cut out? Not the brightest of engineers and IKB will be turning in the proverbial over my lack of understanding, even with all the help that is at hand on the web. It may be that I'm just being dull :?
I've seen these CSB engines run and they certainly out perform any compensated locos - that I've built or seen to date. Till now I've used Gordan Ashton springing units, with excellent results. But and its' a big but, these CSB chassis locos look easier to set up and have fewer parts to attach to the horn blocks than GA spring units. And the eyesight is definitely not improving, so now is a good time to acquire some new skills. So my thanks to Will for plunging in head first...

regards

Mike

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Re: Loco Suspension, fitting CSBs

Postby allanferguson » Thu Jul 22, 2010 11:46 pm

Will L asked "I'd be interested to know how the suspension on the bogey is arranged."

So this is it. I'm a bit embarrassed about showing this, which is a bit of a lash up, I think. However it does seem to work. It caused me a lot of angst as I was working from the data on the CLAG web site (very helpful). I wanted controlled sideplay. and arranged something similar to Ted Scannel's Midland 2P bogie, with a rigid central structure, and floating outside frames controlled by a single spring beam on each side. However my workmanship is not up to Ted's, and the whole thing ended up so floppy as to cause me to lose confidence and scrap it. It did work, though, and I think the design was sound. So I ended up with this, with no sideplay (I'm relying on the sideplay in the driving axle).
A single springy beam on each side rests on top of the axles which run in slots in the frames. The brass rod through the two original handrail knobs just stops the axles from falling out. The spring beams had to be bent to hide behind the frames and I made a wee jig for that as I may have to make quite a few -- I think these may be too strong.
DSCF0001.JPG


I do apologise for taking over this thread -- I only piped up because of the question about Brassmasters bearings; I'll pipe down now!

Allan F

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dcockling
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Re: Loco Suspension, fitting CSBs

Postby dcockling » Fri Jul 23, 2010 12:44 am

Mike Garwood wrote:Where does the centre of the horn block get measured from to give you the correct starting place, so that you get the correct ride height. I've looked at the CLAG site - thanks Russ loads of vital info there for the uninitiated - but I still don't understand where to start. Is it pot luck? - probably not. Middle of the cut out? Not the brightest of engineers and IKB will be turning in the proverbial over my lack of understanding


Hi Mike,

Did you look on this page on the CLAG site?

All the Best
Danny

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Re: Loco Suspension, fitting CSBs

Postby Flymo748 » Fri Jul 23, 2010 5:31 am

dcockling wrote:
Mike Garwood wrote:Where does the centre of the horn block get measured from to give you the correct starting place, so that you get the correct ride height. I've looked at the CLAG site - thanks Russ loads of vital info there for the uninitiated - but I still don't understand where to start. Is it pot luck? - probably not. Middle of the cut out? Not the brightest of engineers and IKB will be turning in the proverbial over my lack of understanding


Hi Mike,

Did you look on this page on the CLAG site?

All the Best
Danny


Hi Danny,

I read Mike's question in a different way, in the light of recent experiences...

He's using a set of Alan Gibson frames. These come with the cutouts for hornblocks already in place - you don't have axle centres to mark out a centre-line from, and then fret out the rectangular cutouts around them. There is no datum point from which to make the measurements that CLAG's Annex 4 from.

I've had the same problem with my AG J15. I solved that by laying the frames over a scale drawing of the prototype (thank you GERS!) and scribing a line through the axle centres visible on the plan.

An alternative approach would be to use calipers or similar to mark out scaled dimensions from a GA drawing or similar, but that approach may not be possible with AG frames which are (said with a respectful nod to how long they have been available) only approximations of the full outline.

HTH
Flymo
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Will L
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Re: Loco Suspension, fitting CSBs

Postby Will L » Fri Jul 23, 2010 9:30 am

Flymo748 wrote:I read Mike's question in a different way, in the light of recent experiences...

He's using a set of Alan Gibson frames. These come with the cutouts for hornblocks already in place - you don't have axle centres to mark out a centre-line from, and then fret out the rectangular cutouts around them. There is no datum point from which to make the measurements that CLAG's Annex 4 from.

That's how I read Mike's problem too, and I have the same problem coming on the J10. My response will have to wait till I've got there because as yet I have no answer.

allanferguson wrote:Will L asked "I'd be interested to know how the suspension on the bogey is arranged."

So this is it. I'm a bit embarrassed about showing this, which is a bit of a lash up, I think.
Don't be, looks like a neat enough bit of modelling to me.

However it does seem to work. It caused me a lot of angst as I was working from the data on the CLAG web site (very helpful)....
..A single springy beam on each side rests on top of the axles which run in slots in the frames. The brass rod through the two original handrail knobs just stops the axles from falling out. The spring beams had to be bent to hide behind the frames and I made a wee jig for that as I may have to make quite a few -- I think these may be too strong.
I like the look of it, but a quibble follows.
One pre quibble key point, if it works then I wouldn't let self appointed experts waving theoretical quibbles get in your way.
One of the CSB advantages is the ability to change springs easily. Well you've lost that one. Clearly strait wires would produce a very different design, would it mater if they showed if you painted them black?

I asked the original question because I have done battle in this area and the jury is still out. Carrying wheels of all sorts are going to be a problem which I will come back to in due course. Though expect discussion rather than answers.

I do apologise for taking over this thread -- I only piped up because of the question about Brassmasters bearings; I'll pipe down now!

Allan F

O no Alan, the more the merrier. I started this because there was a need and I had an enthusiasm, not because I thought I had any sort of monopoly on expertise!

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Re: Loco Suspension, fitting CSBs

Postby allanferguson » Fri Jul 23, 2010 10:52 am

Will L asked "One of the CSB advantages is the ability to change springs easily. Well you've lost that one. Clearly strait wires would produce a very different design, would it mater if they showed if you painted them black?"

I can actually wiggle the springs in and out to change them. I had to bend them round the axles to ensure they were positively located. I gave myself brain fever using Russ Elliot's equations to get 13 thou springs, but I was very conscious of the difference between theory and practice!

Allan F

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Mike Garwood
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Re: Loco Suspension, fitting CSBs

Postby Mike Garwood » Fri Jul 23, 2010 12:32 pm

Thanks Lads...look forward to seeing the outcome and a way forward with scribing a datum line. Back to finishing another 4 coaches for LMJ.

cheers

Mike

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Will L
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Re: Loco Suspension, fitting CSBs

Postby Will L » Fri Jul 23, 2010 10:55 pm

So why CSB’s

First let’s deal with what CSBs are. Those who already know will have to forgive, amplify or correct what follows. From the feedback to date, I suspect a fair chunk of the audience is going to know all this, but I’ve already written it so…

Simple sprung suspension is becoming popular for wagons and coach bogies, where a single leaf spring, often made of spring steel wire, supports a single wheel. The wire is supported at the ends at two fulcrum points and in turn supports an axle bearing, normally but not necessarily, in the centre. Obviously you need one of these at each end of the axel. When some weight is applied it looks like this.

csb 04 8.jpg
csb 04 8.jpg (6.01 KiB) Viewed 17395 times


If you need to adjust the spring rate you just substitute a thicker or thinner piece of steel wire. The wire we need is available as guitar strings and comes in increments of 1 thou from 7 to 26 thou. The 10 to 14 thou range seems to be were my locos settle but lighter ones may be of value in wagons and on bogies.

These work well. Bill Bedford, Masokits and possibly others, have commercial etches available which will allow you to spring most wagons and coach bogies. And yes I know (some of) the Masokits items use a special etched spring rather than the wire. The key point is that the method is robust, and tolerates enough variation in the weight of the vehicle to ensure it is easy to be successful while working within normally achievable tolerances.

For locos, which typically have a series of wheels to deal with, the idea was extended so that a single spring wire supports all the wheels on one side of the loco. Shared fulcrums are provided between the wheels, and so you end up with something on each side of the loco chassis that looks like this.

csb 04 9.jpg
csb 04 9.jpg (15.93 KiB) Viewed 17395 times


This is a theoretical rather than a practical view. Normaly both the fulcrum points and axle bearings actually have a hole through which the spring passes, so they are trapped to the spring, but they are not firmly attached to it. The classic fulcrum is a Markits handrail knob. The spring must be free to slide through the attachment points as it flexes, but with some form of stop to ensure this movement doesn’t go too far. Typically one end is bent into an L shape, which stops it going one way, and a chassis cross member acts as a stop in the other direction.

And there you have it. That is a Continuous Springy Beam. As the spring is continuous it not only provides some spring action, it also provides a degree of compensation or distribution of weight between the wheels, and IMHO the result is significantly better than either strait compensation or springing.

So why are they so good?


I first came to CSBs when I was considering how to go about a LNER Robinson ROD 04 2-8-0. Up to then I was happy with compensation, and didn’t think I wanted to get involved in the difficulties of getting springing to work. However the thought of compensating all those axles was giving me mental indigestion. I had also had recent experience with a compensated 4-4-0 which had proved more difficult to get right than I had expected. So, as I had been reading Father Teds Scannell’s words on the topic of CSBs at the time, I gave them a go.

The outcome was a revelation, and had a number of interesting properties.
1. To start with, it was remarkably simple to make, certainly a lot easier that compensating across 4 axles.
2. The method appears to be robust, that is, it goes on working well when practical difficulties cause variations from the theoretical best case application.
3. Rather than the floppy, wheels hanging everywhere effect, you typically get on a compensated chassis, the wheels are held more or less in the right place even when lifted from the track
4. It was easy to adjust the spring rating on a CSB, and hence the performance on track and the ride height, just by changing the spring wire for a thicker or thinner bit.
5. Best of all the loco worked and worked well. It kept to the track, had good adhesion, ran with the slow ponderous gate that you’d expect from a heavy goods loco, and didn't lurch over any irregularities in the track.

Having done the loco I used the same principles on the six wheel tender which is very different but proved to be equally successful. I was sold.

Here we go, pictures at last.

csb 04 1.jpg
This is the O4 chassis which converted me. The frames from this ex Anchorage kit came with standard 6mm hornblock cut-outs marked but not etched away. The space between the frames is wonderfully empty, just consider what I would have needed in here if compensation was in order. The only problem is that it is now too empty, and cries out for inside valve gear.
csb 04 1.jpg (141.79 KiB) Viewed 17395 times



csb 04 6 v2.jpg
It is pretty standard CSB fare, the fulcrum points are Markits best chunky handrail knobs. These put the beam 1mm clear of the frames. The horn blocks are by Highlevel. They do an etched component, which you can see soldered to the supplied horn block, and that gives a suspension point that lines up reasonably well with the handrail knobs. The wire beam would normally go further through the handrail knob than shown here.
csb 04 6 v2.jpg (183.96 KiB) Viewed 17395 times


csb 04 2.jpg
The same thing from underneath. If there was a snag-ett, it was that the Highlevel horn blocks didn't leave much room between the frames for the gearbox. The DriveStrecher, which was always part of the plan to keep the drive on the 3rd axel while having the gearbox hidden in the firebox, is thinner than the standard gearbox but still only just fits. I had to thin down the horn block and the axel bearings on the gear box to get it all in. Just as well no side play was required.

I have since discovered that the Highlevel etched component, which is used to give the suspension point with the normal square hornblock, can also be use with a standard 1/8 top hat bearing and makes a perfectly serviceable horn block substitute and takes up a lot less room.

One final point is that the pony truck carries none of the loco weight and is not sprung; instead it carries a hefty lead weight to keep it honest.
csb 04 2.jpg (165.33 KiB) Viewed 17395 times


csb 04 3.jpg
This is the O4 tender Chassis. This too is built using CSBs, and the things that seem most scary about CSB construction, like where do the fulcrum points go, apply just as much to this as the loco chassis. As this is the bit of the J10 I’m going to tackle first, I thought I might as well throw in this picture too. You will note that the bearing arrangements are much simpler. Proper hornblocks aren’t used. As we have no connecting rods we don’t have to bother about maintaining any critical axle to axle dimensions. The axles actually run in slots in the, quite chunky, inside frames that came with the kit.


csb 04 4 v2.jpg
The weight is taken by the axles running in small 2mm top hat bearings let into a plate, central in this picture, which substitutes for a hornblock. The plate also caries the suspension point. As planned this was to be a simple hole through the turned in tab, but as there was nothing to keep the bearing plate vertical, they didn't stay vertical. A short length of brass tube was substituted and fixed the problem. The necessary consistent distance from axle to suspension point was achieved by jig drilling the plate. Overall this arrangement has much in common with the Bill Bedford and Masokist sprung wagon systems mentioned before. The bearing plate moves against the frame which you can see in the picture was left unpainted where they meet.
csb 04 4 v2.jpg (169.48 KiB) Viewed 17395 times


In the next instalment we will go into marking out the frames, and we will have to start thinking about how we decide were those fulcrums are going to go. That will be fun..

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Re: Loco Suspension, fitting CSBs

Postby DavidM » Sat Jul 24, 2010 1:17 am

Great stuff, Will.

I'd be interested to know more about your pickups - they look very clever.

Like you, my first venture into CSBs was a 8-coupled chassis - for a Brassmaster's Super D. I used the London Road hornblocks - with the LRM attachment system and their 2mm axleboxes on the tender which is also fitted with CSBs. Pickup is via the American system. One point worth making is the need to plan chassis spacers carefully to allow a clear run for the beam - in the case of the Super D, it was possible to use the centre (bulkhead) spacer as a fulcrum point as the chassis is symmetrical.

Drive is via a HighLevel gearbox onto the third (flangeless) wheelset. This set of axleboxes needed thinning down as well to accomodate the drive with minimal sideplay and there is a modified attachment to the CSB. The fulcrum points were determined using Will's 4-coupled version of the spreadsheet originally done by Roger Wyatt - available on the CLAG website.

David Murrell
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David Thorpe
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Re: Loco Suspension, fitting CSBs

Postby David Thorpe » Sat Jul 24, 2010 7:33 am

DavidM wrote:Great stuff, Will.

I'd be interested to know more about your pickups - they look very clever.

Don't they just! Me too please!

It's astonishing how bulky spring wires look in close up pictures! I'd be very interested in knowing how people decide which gauge wire to use - I'd assume, for example, that that used on the tender is considerably thinner than that on the loco. Is it a matter of trial and error, with a number of (presumably) different gauge guitar strings to hand, or are mathematical calculations required?

David

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Russ Elliott
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Re: Loco Suspension, fitting CSBs

Postby Russ Elliott » Sat Jul 24, 2010 8:25 am

DaveyTee wrote:Is it a matter of trial and error, with a number of (presumably) different gauge guitar strings to hand, or are mathematical calculations required?

The spring diameter chosen will depend of course on the weight of the loco. For the 3-axle case, Roger Wyatt's spreadsheet tells you what diameter will give your desired axle deflection. For a nominal 0.5mm axle deflection, the answer is usually 0.33mm (0.013") or 0.355mm (0.014") for most 0-6-0s in the 200g overall weight region. People have different ideas about what locos should finally weigh, so trying different spring diameters to get a ride characteristic you find good on your track is no bad thing. Tenders will not normally require such strong springs, although opinions on what model tenders should weigh also vary widely!

For those who haven't got Excel, or are not confident about working the spreadsheet (it's quite easy when you get the hang of it), or need plots for 4-coupled locos, feel free to contact me.

I'm also well impressed by Will's pickups - the chunky stabiliser rod is interesting.

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Horsetan
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Re: Loco Suspension, fitting CSBs

Postby Horsetan » Sat Jul 24, 2010 1:45 pm

Russ Elliott wrote:.....I'm also well impressed by Will's pickups - the chunky stabiliser rod is interesting.


Reminds me of those distillery tubes, or something you'd see in a mad scientist's laboratory!
That would be an ecumenical matter.

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Will L
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Pickups

Postby Will L » Sun Aug 01, 2010 9:08 am

Horsetan wrote:
Russ Elliott wrote:.....I'm also well impressed by Will's pickups - the chunky stabiliser rod is interesting.


Reminds me of those distillery tubes, or something you'd see in a mad scientist's laboratory!


I'm flattered people are interested and the mad scientist may have more to do with this than I'd like. As interest has been express I'll fill you all in, but not now there is to little ti........ .. .. . . .


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