0-6-0 CSB with one fixed axle

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97xx

0-6-0 CSB with one fixed axle

Postby 97xx » Mon Nov 02, 2020 8:20 pm

Hello from an 00 gauge modeller with a question about CSB.

I've decided to go High Level CSB on a Q1 0-6-0 chassis i'm building. Agreed probably not necessary in 00 but I'd like the challenge of building my first compensated chassis.

The issue I have is that there is no room to get the CSB beam past the gearbox (and also an inside chassis etch) to operate on the rear axle.

So, I will be fixing the rear axle.

My question is how do I design the CSB to work on what will be a 4-coupled compensated front and centre axle with the fixed rear.

Intuitively I'd run the calculations (using one of the well-known spreadsheets) in the 2-axle mode with essentially 2/3 of the loco unsprung weight divided pretty much equally between the front two axles.

However, if I do this won't I get a nose-down attitude as the set which the front two axles take will be 'pivoting' about the rear?

So, in my non-expert mind, it strikes me I should lower the centres of the front two hornblocks/axles by the amount the s/s calculates I will get in deflection and then when placed on the track, the loco will sit level?

Am I right or have I lost the plot?

Thanks so much. I've pored over the site and just cannot find the answer to this!

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Will L
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Re: 0-6-0 CSB with one fixed axle

Postby Will L » Mon Nov 02, 2020 11:43 pm

97xx wrote:Hello from an 00 gauge modeller with a question about CSB.

I've decided to go High Level CSB on a Q1 0-6-0 chassis i'm building. Agreed probably not necessary in 00 but I'd like the challenge of building my first compensated chassis.

The issue I have is that there is no room to get the CSB beam past the gearbox (and also an inside chassis etch) to operate on the rear axle.

So, I will be fixing the rear axle.

My question is how do I design the CSB to work on what will be a 4-coupled compensated front and centre axle with the fixed rear.

Intuitively I'd run the calculations (using one of the well-known spreadsheets) in the 2-axle mode with essentially 2/3 of the loco unsprung weight divided pretty much equally between the front two axles.

However, if I do this won't I get a nose-down attitude as the set which the front two axles take will be 'pivoting' about the rear?

So, in my non-expert mind, it strikes me I should lower the centres of the front two hornblocks/axles by the amount the s/s calculates I will get in deflection and then when placed on the track, the loco will sit level?

Am I right or have I lost the plot?

Thanks so much. I've pored over the site and just cannot find the answer to this!


I'm sorry but I don't see fixed axles and CSB as a sensible mix. If I thought about it long enough I might be able to tease out what might be going on, but I'm not sure I want to spend the necessary time and its not intuitive. In any event, for me a fair part of the reason for adopting sprung solutions is to avoid the consequence of fixed axles on the smooth running performance of the loco. If you really can't avoid a fixed axle then standard compensation will produce significant improvements in performance particularly in electrical continuity and an ability to deal with uncertain track work. It will also gives experience with the use of hornblock systems which is worth gaining. I started out compensating 00 chassis on 0-6-0 tanks so than ran well enough for exhibition use.

However, I probably can help in providing ideas as to how you can get CSB wires, gearboxes and hornblocks between the frames at the same time, and how to deal with other obstructions the CSB wire needs to pass.

Jeremy Suter
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Re: 0-6-0 CSB with one fixed axle

Postby Jeremy Suter » Tue Nov 03, 2020 8:43 am

Apart from the challenge, I assume this is about keeping the wheels on the track all the time to give better pick ups.
You don't say which gear box you are using I thought there are some which are slim enough for use of hornblocks in OO.
You could allow the driving axle to move up and down with the spring wire closer to the chassis side and resting on top of the axle, or the top hat bearing, rather than the thicker hornblocks if not enough space.
Or if only spring the front 2 axles. The front only allowing it to go down and not up therefore keeping the front height correct. The middle axle is the one that needs both up and down movement. In reality there is not that much movement in the axle as the loco travels along the track usually only dips and bumps or the gap in the frog of the points.

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JackBlack
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Re: 0-6-0 CSB with one fixed axle

Postby JackBlack » Tue Nov 03, 2020 9:29 am

I would suggest before giving up on CSB completely, explore which High Level gearbox you use, because some are narrower than others, and also look at using High Level slimline hornblocks on the driven axle. I'm not saying this will definitely work, but it may do.

davebradwell
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Re: 0-6-0 CSB with one fixed axle

Postby davebradwell » Tue Nov 03, 2020 9:35 am

if you want to assess the benefits of springing then you have to spring all the axles. If you have a fixed axle then the game's over and whether you spring or compensate the others it won't behave like the real deal, although, as has been said, the pick-up will probably be improved. The solution is in the gearbox and slim types have been available but I don't know the current situation. It's certainly possible to thin down the axleboxes and hornguides (that's the bit soldered to the frames) to gain significantly more space.

More ideas on this have just appeared.

DaveB

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David Thorpe
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Re: 0-6-0 CSB with one fixed axle

Postby David Thorpe » Tue Nov 03, 2020 5:28 pm

I must admit that I wouldn't like to try fitting CSBs to an 00 chassis. Even using the slimline gearbox and the slimline hornblocks, I would think it'll still be very fiddly. And even then you're not guaranteed success - One 0-6-0 I built using CSBs ended up seriously front heavy and I was unable to correct it, so ended up using conventional compensation instead. Perhaps if I'd given it greater thought before I started I might have had more success, but there it is - compensated, the loco runs well.

Most people here will have 0-6-0s that work well with a fixed rear axle and beam compensation. I certainly do. CSBs may glide, but you can bet your boots that the prototype didn't always and you're really only going to get serious "lurches" if your track is bad. Even with CSBs on the front pairs of drivers as you suggest, the fixed rear axle will lurch on bad track which really negates the whole perceived advantage of CSBs. Also, weight distribution isn't nearly as important with traditional beam compensation, though you'll still have to give it some thought to get the best possible haulage if that aspect is important.

So before you decide what to use on the loco, why not try CSBs first on the tender? CSBs really are ideal for tenders. Once you've done the tender chassis, which I assume will have the same inside measurements as the loco one, you'll be able assess just how much room there would be for CSBs if a motor and gearbox was to be brought into the equation.

DT

97xx

Re: 0-6-0 CSB with one fixed axle

Postby 97xx » Thu Nov 05, 2020 6:07 pm

Thank you all for some thought-provoking suggestions.

I do understand that trying to do all this in 00 is potentially a combination of unreliable and/or unnecessary. I'm probably over-swayed by the engineering challenge of it...

My fault being in 00 of course, but even with a fairly narrow HL 'box and spacesaver HBs I have to attach etches to INSIDE the frames as it's a Q1 and some of these which represent the firebox unfortunately go down low enough (as they're visible through cutouts in the frames) to get right in the way of CSB gubbins. Hence my thinking I'd do a fixed axle at the driven back, rather than completely ruin the CSB by finding it's all jammed up.

I have Mike Sharman's FlexiChas book and perhaps I need to revisit that as I'm still keen to experiment with horn blocks and compensation of some sort - and the HL HBs would appear still suitable for that arrangement.

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Paul Willis
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Re: 0-6-0 CSB with one fixed axle

Postby Paul Willis » Thu Nov 05, 2020 7:25 pm

97xx wrote:I have Mike Sharman's FlexiChas book and perhaps I need to revisit that as I'm still keen to experiment with horn blocks and compensation of some sort - and the HL HBs would appear still suitable for that arrangement.


Well, with that combination you should soon have a smooth running chassis. Perhaps it won't be quite as smooth and quiet as a fully sprung chassis (I won't go into the Judean Peoples Front versus the Peoples Front of Judea argument of whether it should be CSBs or individual springs) but it will run well, and the pick-up will be greatly improved.

The High Level hornblocks are a dream to use, and are perfectly . Easy to construct (when the instructions say don't use solder, they really mean it) and easy to fettle. You will need a brush or two of a needle file to get them running smoothly, as the guides are better under-etched than over-etched and loose. They are an excellent component - personally, I won't think of using anything else.

All the best with your build.
Cheers
Paul
Beware of Trains - occasional modelling in progress!
www.5522models.co.uk

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Will L
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Re: 0-6-0 CSB with one fixed axle

Postby Will L » Thu Nov 05, 2020 8:27 pm

97xx wrote:My fault being in 00 of course, but even with a fairly narrow HL 'box and spacesaver HBs I have to attach etches to INSIDE the frames as it's a Q1 and some of these which represent the firebox unfortunately go down low enough (as they're visible through cutouts in the frames) to get right in the way of CSB gubbins. Hence my thinking I'd do a fixed axle at the driven back, rather than completely ruin the CSB by finding it's all jammed up.

I thing CSBs will go in on all axles. Typically the wire sits 1mm clear of the back of the frames. It has to go behind the horn guides which are two layers of 12 thou of brass. If your Firebox detail is no wider than that, it wont interfere with the wires.

As to the gearbox, a HL SlimLiner, as Nick(JackBlack) suggested, is only 6.3 over the gearbox sides on the drive axle and should go in no problem, but you will probably need to use a DriveStreacher to get the wider part of the gearbox (12mm) above the level of the wire.
I have Mike Sharman's FlexiChas book and perhaps I need to revisit that as I'm still keen to experiment with horn blocks and compensation of some sort - and the HL HBs would appear still suitable for that arrangement.

You need the same ones for either compensation or CSBs.

CornCrake
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Re: 0-6-0 CSB with one fixed axle

Postby CornCrake » Thu Nov 05, 2020 9:36 pm

Out of interest, what make of etched chassis are you using?
Steve

97xx

Re: 0-6-0 CSB with one fixed axle

Postby 97xx » Fri Nov 06, 2020 7:40 am

Steve, it's a South Eastern Finecast n/s etched chassis. HL 'box and spacesaver HBs, Markits boxpoks, Mashima.

Basically to replace an original Keyser's 1/2" x 1/16" brass 'bar and spacer' one with poor wheels and motor -and which curiously also has the wrong wheelbase, odd given it's not designed for a RTR replacement of any kind!

The K's body will need a lot of work to bring up to an acceptable standard, but that is all straightforward enough. After all, I seem to have time on my hands again, and in the first lockdown a 40-year old K's 97xx was rebuilt with some success!


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