0-4-0T csb

[Andy W]

I think I might be converted to this CSB lark because I'm looking at building a tricky (outside cylinder) 0-4-0T with them. I've seen reference on RM web and CLAG to "springy equalising beams". I assume these have only one central pivot? If so is this fixed or does it slide in its locator? this got me wondering that if you can solder this point, then the term "equalising beam" is a bit misleading - as a two point beam would be inherently unstable.

I assume the springiness (good technical term that) makes this irrelevant? I'm not nit picking over terminology here, just curious.

I'm hoping to use a fixed spring on split axles, the springs would then also pick up power from Maygib bearings - thus allowing me to use the spacers in the kit which locate the cylinders.

I might even be tempted to do this as one of those blog "thingies".

[Russ Elliott]

I've seen reference on RM web and CLAG to "springy equalising beams". I assume these have only one central pivot?

Yes.

If so is this fixed or does it slide in its locator?

It is not fixed. It is allowed to rotate about its fulcrum point.

this got me wondering that if you can solder this point, then the term "equalising beam" is a bit misleading - as a two point beam would be inherently unstable.

If it was allowed to rotate about its fulcrum point, an 0-4-0T containing such a beam would indeed be inherently unstable. If it was soldered at the fulcrum point, there would be no equalisation along the beam itself, and would have the effect of two separate cantilever springs.

I can't see much point in putting a CSB into an 0-4-0T: pitch stability will be more manageable with 4 separate twin-support springs.

[grovenor-2685]

Just, perhaps to be clear, springy equalising beams, or even non-springy ones are not suitable for an 0-4-0 as they do not provide any means of keeping the chassis level. They are normally recommended for locos such as a 4-4-0 where the bogie will keep things level.
Either 4 individual springs or a CSB can be used as it does not have this problem. For joint use as a pick up arrangement then 4 cantilevers should be a good way to go.
Make sure the current passing through your springs cannot warm them up to the point where they lose temper.
Keith

[Andy W]

Thanks chaps, that's a great help.

[Will L]

I can't see much point in putting a CSB into an 0-4-0T: pitch stability will be more manageable with 4 separate twin-support springs.

I suppose you can argue that logically, but I think it comes under the same heading as CSB chassis oscillating on there springs. It isn't actually a problem because the friction between axle block and horn guides damps it out.

While I suspect either will work perfectly well, the choices in my mind is between 8 fulcrum points and 4 wires or 6 fulcrum points and 2 wires. A strait CSB just looks simpler. That is unless the 4 wheel are at the far comers of a relatively long wheel base (i.e. I'm not about to CSB your average 4 wheel wagon).

Will

[Horsetan]

I thought it would be easier to treat an 0-4-0T in the same way as a Bill Bedford coach bogie.....

[Will L]

I thought it would be easier to treat an 0-4-0T in the same way as a Bill Bedford coach bogie.....

The Bill Bedford bogies I'm familiar with are CSBs (i.e. 6 fulcrum point and two springs).

Will

[jjnewitt]

Think no more about CSBs and stick four individual springs in it. The time taken to deal with the extra fulcrum points will be more than compensated by the lack of time taken deciding between the two.

[Horsetan]

I thought it would be easier to treat an 0-4-0T in the same way as a Bill Bedford coach bogie.....

The Bill Bedford bogies I'm familiar with are CSBs (i.e. 6 fulcrum point and two springs).

...which is what I meant

[Will L]

Think no more about CSBs and stick four individual springs in it. The time taken to deal with the extra fulcrum points will be more than compensated by the lack of time taken deciding between the two.

Truly not true. 2 axle CSBs are trivial and don't require a lot of thought. It must be symmetrical about the middle fulcrum which goes half way between the axles, the outer two should be about half as far from the axle as the centre fulcrum but it is not critical, so long as they don't get ridiculously close to the axle, and can go in where it suits the chassis.

If your determined to use the spread sheet you can feed in the fulcrum points and the final loco weight and it will tell you the right size of wire.

Will

[Alan Turner]

The 0-4-0 case is trivial if you make the fulcrum points symmetrical and I did think of not including the case in my spreadsheet for that reason.

However it is not trivial if the Centre of Gravity is not symmetrical about the wheel base so the spreadsheet enables you to position the fulcrum points to make the CG coincident with the Centre of Reaction.

Also, even if the fulcrum points are symmetrical, the spreadsheet enables you to calculate the diameter of wire/weight of loco required.

Regards

Alan

[billbedford]

I can't see much point in putting a CSB into an 0-4-0T: pitch stability will be more manageable with 4 separate twin-support springs.

I think you are heading for a metaphorical beating up on Friday………………..

lookyou 'ere

If anyone is contemplating this, easy way of placing the anchors is:-

Centre anchor -- midway between the axles
Outer anchors -- one third of the wheelbase outboard of each axle.

This will have the spring forming a 'natural' curve with the highest point of the spring wire co-inciding wth the axles.

[Russ Elliott]

My remark about a CSB in an 0-4-0 has been misinterpreted, somewhat predictably. Let me stress I have no argument between a CSB and discrete springs for an 0-4-0 in terms of the springing characteristic. My point about discrete springs being more 'manageable' is this: whereas for a 4-wheel wagon or coach bogie, getting the final CofG exactly in the middle of the wheelbase is given by the nature of what is being supported, that is not such an obvious assumption or conclusion for a loco. If, for whatever practical reason, the final CofG is off-centre, a remedy is available if using discrete springs - altering the springrate of one axle. For an off-centre CofG loco with a CSB, you're up a creek without a paddle (unless resorting to packing an axle carrier height of course).

[zebedeesknees]

Oh dear, more ol' tosh on CSBs.. One would have to make quite an effort to get the centre of mass significantly off centre in an 0-4-0T! And how much difference that would make is more a game of conjecture than established fact. The point of using CSBs is just one of simplicity. I would suggest believing that discrete springs are more manageable could be credible when one sees an 0-4-0T that has been made.. to work.. by the proponent. 'Christine' - see Bill's lookyou 'ere link - isn't precisely symmetrical and works extraordinarily well. 30 wagons is quite enough. Or should that be 'are' quite enough...? Discrete springs would have been an incredible pain to design, fit and adjust! Horsetan is quite right, look to a Bedford bogie, the design should use the same principles.

[Russ Elliott]

Oh dear, more ol' tosh on discrete springs... (can I assume we've all been misled by BB W-irons if they are such "an incredible pain to design, fit and adjust"?)

For the 2-axle case, CSBs are more critical about CofG placement compared to the use of discrete springs. The chassis slope produced by an off-centre displacement of the CofG in the CSB case will be approximately double that of discrete springs set for the same weight and static deflection. This is because of the additional "equalising" moment along the CSB (and hence their virtue in the Bedford bogie). The differential between the slope relationships is I think linear between the CSB and non-CSB cases, but offset v slope values can be plotted with some spreadsheeting if anyone wants to pursue the issue.

[billbedford]

Perhaps you should build one and show us………...

[Will L]

Oh dear, more ol' tosh on ... springs...

Probably, some may decided to read no further.

For the 2-axle case, CSBs are more critical about CofG placement compared to the use of discrete springs. The chassis slope produced by an off-centre displacement of the CofG in the CSB case will be approximately double that of discrete springs set for the same weight and static deflection. This is because of the additional "equalising" moment along the CSB (and hence their virtue in the Bedford bogie).

True I think, though I haven't done the maths to check.

The differential between the slope relationships is I think linear between the CSB and non-CSB cases, but offset v slope values can be plotted with some spreadsheeting if anyone wants to pursue the issue.

Probably best to remember that hight of the CofG above chassis also becomes a factor once the chassis begins to slope. Simple linear answers don't look very likely.

Of course, Alan was correct in saying, a few post back, that using his spread sheet you can adjust the CSB fulcrums so it will compensate for an off centre CofG and sit level. But the penalty of having an off set CofG (CSB or not, sitting level or not) is that you will get less adhesion for a given loco weigh. The lesson is that it is better to take an interest in where your CofG is and weight to achieve balance rather than than to stuff in the maximum amount of weight and hope.

Of course once your CofG is central then the CSB is probably a simpler solution.

Will

[Trevor Grout]

Perhaps you should build one and show us………...

The Classic CLAG "Go On Then" has been issued.....

[Horsetan]

Perhaps you should build one and show us………...

The Classic CLAG "Go On Then" has been issued.....

Would that make it a G.O.T.Cha(ssis)