Carr's torsion suspension

[nberrington]

Has anyone any experience with this system?
See below:

http://www.emardee.org.uk/epages/BT2573 ... ucts/40102

thanks!
Neil B

[DaveyTee]

No, but it seems very reasonably priced! Unfortunately the link to the pdf instructions doesn't work.

Quite a range of sprung buffers as well.

DT

[craig_whilding]

I didn't realise Carrs had any connection to Model Railway Developments?

I had a look at this system and thought it was overly complex and had more issues with placing weight and couplings so prefer the conventional sprung type. His coach system is intriguing with the unconstrained swing links.

[grovenor-2685]

I didn't realise Carrs had any connection to Model Railway Developments?

Hubert Carr sold his original business to Brian Lewis and, I suppose, got a bit bored with retirement so started up again as MRD.

I think "Carrs" as a business name is still with C&L under the new owner, so should not really be applied to MRD except perhaps as a possessive as it is in the header.
Regards
Keith

[craig_whilding]

I didn't realise Carrs had any connection to Model Railway Developments?

Hubert Carr sold his original business to Brian Lewis and, I suppose, got a bit bored with retirement so started up again as MRD.

I think "Carrs" as a business name is still with C&L under the new owner, so should not really be applied to MRD except perhaps as a possessive as it is in the header.
Regards
Keith

Ah thanks, I was thinking in terms of business name and didn't realise it was the owner's name.

[nberrington]

Sorry to confuse everyone.
I suspect this product is properly called "MRD torsion suspension underframe"
Attaching Carrs to it was a natural error, as MRD would seem to be his baby.

Here in North America we are usually more cautious about attaching names to things (patent laws etc). C&L obviously would have paid for the existing goodwill when Mr Carr left. He clearly left his name behind, and does not refer to MRD products as "Carrs". (My mistake, no inference of his)

Anyhow - I wondered if it was any better than a sprung underframe. My short test bench doesn't seem to discriminate much between compensated and sprung, but the turnouts don't like half-baked-semi-working springing - ie if the axelbox gets stuck in the "up" position, the wagons tilt most alarmingly. Having said that - out of true wheelsets seem to more important as determinants of less than perfect running.

NB

[Will L]

I wondered if it was any better than a sprung underframe. My short test bench doesn't seem to discriminate much between compensated and sprung, but the turnouts don't like half-baked-semi-working springing - ie if the axelbox gets stuck in the "up" position, the wagons tilt most alarmingly...

But it is a sprung under frame, and the only way we will know how they compare with others for sure is when somebody builds a few. Unfortunately the link to the PDF instructions isn't working so we can't check that for more details. Despite a good price it wont be me who does the comparison because on first sight it looks as if it may be a bit overcomplicated. Also, remembering the failings of another torsion bar suspension system -the MTJ coach bogies, I'd wonder if there could be problems with solder joints on the torsion bars failing.

I don't think existing system are naturally any more "half baked" than this one. If you don't get any suspension system on right they will all let you down. With sprung systems with functional W irons, you do have to ensure your W irons stay vertical or they may jam as you describe. This would apply to this system too. Keeping the W irons vertical means getting the width over the W irons matched to the axle and bearing set you are using. For the ins and outs of that see Bearing and axle interfaces for coaches and wagons. on the CLAG website.

Will

[nberrington]

Thanks Wil.
I guess most of it is in the building phase of a kit - getting the W irons "just so", and ensuring the bearing carrier moves freely.
Would be the same regardless of what system one uses.

NB

[Flymo748]

Has anyone any experience with this system?
See below:

http://www.emardee.org.uk/epages/BT2573 ... ucts/40102

thanks!
Neil B

There have been a couple of comments about the lack of a download of the pdf file of instructions...

I bought a set of the etches/wires that make up this system a coupleof years ago with a view to trying it out and seeing how it compared with compensated wagons. Suffice it to say that I haven't got around to building anything that will use them yet :-/

However I do have the instructions (and could find them easily in my kit mountain!) so I scanned them this morning:

I hope that this gives some assistance. On the basis of no experience whatsoever, i suspect that this is an over-complex solution for which we now have simpler alternatives. It won't stop me having a go at trying them though!

Cheers
Flymo

[Will L]

...However I do have the instructions ....

Sorry Paul but i think those are the instruction for this rather different solution

http://www.emardee.org.uk/epages/BT2573 ... ucts/40101

Will

[Flymo748]

...However I do have the instructions ....

Sorry Paul but i think those are the instruction for this rather different solution

http://www.emardee.org.uk/epages/BT2573 ... ucts/40101

Will

That's going to teach me to make assumptions from the title and not click the link!

It looks (the picture is a little confused and busy) that it is the same concept, but in a "fully featured" version, whereas the plates and wires that I got allow you to construct the suspension using your own choice of w-iron, solebar, etc.

I still don't think that I'm convinced by the full-fat version though!

Flymo

[James Moorhouse]

His coach system is intriguing with the unconstrained swing links.

The following excerpt is from the MRD website:

4mm Coaches
The current range is based on the concepts of 'swing link' suspension. This is how prototype coaches are mounted on their bogies. It means that the body sways about an axis near the roof, instead of rocking on the top of the bogies. Even on dead flat track there is a need for flexibility in the bogie since the wheels are coned, and any sideways movement will cause one wheel to ride up, and the other down. This means that the likelihood of a derailment is increased for a solid chassis - even on level track. Not only should the bogies have this flexibility, but it is required between the bogies as well. However to achieve this it is important that the bogie pivots permit rotation about the vertical axis but only about this axis.

I recently read a 1950's paper on bogie design by W.S. Graff-Baker, London Transport's then Chief Mechanical Engineer (Railways), which lead me to question whether our model bogies need any flexibility in the lateral plane. It was concluded that any lateral forces that occur on our models are very small compared to those on the prototype and that swing link suspension on our models would be a luxury too far - our model passengers don't give us any feedback about the quality of their ride anyway. Having said that it would be interesting to watch the dynamics of a model coach fitted with bogies with swing link secondary suspension.

Another point is that not all prototype coaches were mounted on their bogies via swing link suspension, for example Dean bogies, and what goes on under today's modern multiple units is somewhat removed from this concept of bogie design.