'Genesis' 4 & 6 wheel coaches in OO Gauge - New Announcement

[Compound2632]

1 minute ago, Mark Saunders said:

For a steel chassis see this link.

 

https://PaulBartlett.zenfolio.com/paulbartlettsrailwaywagonphotographs/e540b3a6a

 

Mark Saunders

 

Whilst grossly out-of-period, that wagon does illustrate the axleguards-outside-the-springs arrangement. It's not clear how the axleguards are secured to the solebars there - I'm guessing they might have a 90 degree bend and be bolted to the solebar flange from below? 

[Compound2632]

1 minute ago, Miss Prism said:

 

Yes, a bit of that, but the biggest skimping is on the width of the footboards.

 

There's lot of fudging needed on every lateral.

 

 

There's no skimping on footboard width needed if the front face of the solebar is in the correct plane.

[Compound2632]

2 minutes ago, Dunsignalling said:

 

I've always considered that the least troublesome solution to r-t-r 6-wheelers is probably the old dodge of having the axle at one end fixed with the remaining two mounted on an inside-frame bogie that can turn within the axleguards. The wheels only need to move by +/- a couple of mm to deal with No.2 curves.

 

 

The drawback of that arrangement, compared to the admittedly more complicated Cleminson arrangement, is that it results in an asymmetric effective wheelbase and different overthrow at each end of the vehicle. 

 

3 minutes ago, Dunsignalling said:

 

Just avoid the dog's breakfast that Dapol employed on the Stove R they did for Hornby Magazine please Hatton's. That was completely compromised in appearance by fitting undersize wheels in order to create about five times more flexibility than anyone needs. 

 

 

I had the misfortune to buy one of those. So many degrees of freedom that it didn't know which way to go. Don't even mention the body, which was the part it ought to have been trivial to get right. Consider it a warning from history.

[Miss Prism]

2 minutes ago, Compound2632 said:

 

There's no skimping on footboard width needed if the front face of the solebar is in the correct plane.

 

There is if the front of the footboard is compromised, which it is, because of the loading gauge infringements on 2nd radius curves.

 

[Compound2632]

3 minutes ago, Miss Prism said:

 

There is if the front of the footboard is compromised, which it is, because of the loading gauge infringements on 2nd radius curves.

 

 

Yes, that's understood, but I don't think the overall look is helped by setting the solebars too far back. 

 

It's inevitable that the whole thing will be riddled with compromise, as is all railway modelling.

[Wickham Green]

1 hour ago, Compound2632 said:

One way round 2nd radius curves would be to use an inside-bearing Cleminson arrangement, although this would increase the end overthrow as the effective wheelbase would be the distance between the Cleminson pivot points - say 2/3 - 3/4 of the actual wheelbase. The NEM socket would be part of the Cleminson inside bearing unit, which would be an advantage in keeping the coupling nearer the centre line of the track.

 

On the other hand, Hornby's solution (with the Palethorpes sausage / LMS milk van) of a floating centre axleguard / spring unit, whilst hideous in their implementation, might be doable if obscured by the footboards.

 

A dodge used on some prototype designs was to attach the centre axleguard to the outside of the solebar. On the model, this would allow for thinner axlebox/spring, increasing the width available for the centre axle unit to slide.

 

@Miss Prism, thank you for drawing attention to the steel solebar solecism - wood would be much more typical.

 

If there's one thing we're growing to understand from this thread, it's why this hasn't been attempted before!

The true Cleminson arrangement, I believe, simply pivoted the outer axles with no extra sideplay - but the arrangement adopted by Brassmasters with an intermediate pivot is more effective for model railways, for sure.

 

The other 'way round' the six-wheeler 'problem' would be an optional flangeless wheelset for those who need it ......... or, perhaps, an optional flanged wheelset for those who can accommodate it and might have more experience of swapping such things !!?!

[Compound2632]

Thinking in terms of a long fixed wheelbase (with floating centre axle) together with the need to avoid excessive overthrow for the coupling, what is the arrangement on existing long-wheelbase models such as the utility vans and CCTs?

[RLWP]

2 hours ago, Mark Saunders said:

Alas it is descending into I want this and that ; that's not correct it should be like this!

 

Sorry to say but it has became a cross between a "Camel" and the "curate's egg"!

 

Mark Saunders

 

I've avoided being norty and asking for LNWR Commode door handles...

[Dunsignalling]

20 minutes ago, Compound2632 said:

Thinking in terms of a long fixed wheelbase (with floating centre axle) together with the need to avoid excessive overthrow for the coupling, what is the arrangement on existing long-wheelbase models such as the utility vans and CCTs?

Hornby just fit a NEM pocket with the usual degree of flexibility, ditto Dapol but with a different way of achieving the flexibility.

 

Bachmann fit a CCU, better than the ones on early Mk1s, but some work better than others.

 

I remove all of the above and fit #146 Kadees directly to the underside of the vehicle, except those with fishbelly buffer beams (Bachmann BR CCT and Horsebox), which get #141s. 

 

John

[melmerby]

1 hour ago, Dunsignalling said:

 

Just avoid the dog's breakfast that Dapol employed on the Stove R they did for Hornby Magazine please Hatton's. That was completely compromised in appearance by fitting undersize wheels in order to create about five times more flexibility than anyone needs. 

 

John

 

1 hour ago, Compound2632 said:

I had the misfortune to buy one of those. So many degrees of freedom that it didn't know which way to go. Don't even mention the body, which was the part it ought to have been trivial to get right. Consider it a warning from history.

I bought one without knowing what compromises there were. (Note to self: do your research before buying!)

I ended up fixing the end axles and made sure the centre one could move side to side. Much better trackholding i.e it stayed on the track rather than taking to the shubbery at the slightest curve.

After all Hornby's long wheelbase CCTs work OK with a longer wheelbase and no silly swivelling.

The 12mm wheels however are unforgiveable. What where they thinking of?

Edited October 18, 2019 by melmerby

[Dunsignalling]

1 hour ago, Compound2632 said:

 

The drawback of that arrangement, compared to the admittedly more complicated Cleminson arrangement, is that it results in an asymmetric effective wheelbase and different overthrow at each end of the vehicle. 

 

 

I had the misfortune to buy one of those. So many degrees of freedom that it didn't know which way to go. Don't even mention the body, which was the part it ought to have been trivial to get right. Consider it a warning from history.

 

The difference in overthrow is actually quite small but does increase as track radius decreases. It can be eradicated by mounting the odd wheelset on a "half-bogie" with both pivots symmetrically located on the underframe (like a normal bogie vehicle) but with the two subframes articulated together to even out the action. Not drastically more complex to do.

 

Because the axle-guards don't move, this arrangement would avoid any of the issues around footboards as raised by Miss Prism.

 

For auto couplers, NEM pockets can be mounted on the subframes but there's nothing to interfere with fitting scale couplings.

 

John

Edited October 18, 2019 by Dunsignalling

[Compound2632]

@Dunsignalling, now that you've described your system, I think this is the method used on Slaters' Midland 6-wheeler kits - a sort of half-Cleminson arrangement.

 

I agree it must be better for the flexible suspension to be independent of the modelled axleguards, the latter being fixed.

[Allegheny1600]

Hi All,

Guys and @Hattons Dave - seeing as we are discussing the arrangements for the 6 wheel coaches, please observe how my commercial RTR H0 coaches do it. These are absolutely superb, particularly with regard to their running, smooth and very reliable.

Fleischmann 1

Fleischmann 2 (excuse my thumb!).

Roco 1

Roco 2.

With the Roco, you can even see the full length running board.

 

These will take radius two curves with ease, I don't have any radius one but the way they run around R.2, they would probably handle it.

I hope you can see that it is a very simple arrangement, no need for any awkward devices, just simple quality engineering.

Cheers,

John.

[Dunsignalling]

11 minutes ago, Compound2632 said:

@Dunsignalling, now that you've described your system, I think this is the method used on Slaters' Midland 6-wheeler kits - a sort of half-Cleminson arrangement.

 

I agree it must be better for the flexible suspension to be independent of the modelled axleguards, the latter being fixed.

I think you are right about the Slaters' kits.

 

The system still incorporates a certain amount of asymmetry as the centre axle turns in concert with the end one to which it is attached, whereas a true Cleminson arrangement keeps the centre axle square across the vehicle.

 

However, empirically the movement is not great enough to affect running.

 

John

 

 

 

 

Edited October 18, 2019 by Dunsignalling

[Allegheny1600]

In case anyone wants any data about my coaches above, they are;

Fleischmann.

Overall wheelbase: 86mm (fixed)

Sliding w/b: 46mm & 46mm

Amount of lateral movement: +/-2.5mm (5mm total) (approx)

Overall length (inc. fixed buffers): 147mm

Overall width: 35mm

 

Roco. My mistake: The overall brown coach is also Fleischmann, sorry! I do have the very similar Roco version (pre merger) if required.

Overall wheelbase: 86mm (fixed)

Sliding w/b: 46mm & 46mm

Amount of lateral movement: +/-2.5mm (5mm total) (approx)

Overall length (inc. fixed buffers): 145mm

Overall width: 35mm

[Northroader]

2 hours ago, Wickham Green said:

 

The other 'way round' the six-wheeler 'problem' would be an optional flangeless wheelset for those who need it ......... or, perhaps, an optional flanged wheelset for those who can accommodate it and might have more experience of swapping such things !!?!

If you have a flangeless wheel on a long wheelbase it’s fairly certain it won’t take long to drop off the railhead on curvature,  sufficiently to jam up and derail the vehicle.

[truffy]

6 minutes ago, Northroader said:

If you have a flangeless wheel on a long wheelbase it’s fairly certain it won’t take long to drop off the railhead on curvature,  sufficiently to jam up and derail the vehicle.

Even if it’s only the centre wheels that are flangeless?

[Northroader]

You have to be very good with your track laying to be sure that there aren’t any small changes in height over a long wheelbase vehicle, even more so when you get to point crossings.

[uax6]

To some extent a 6 wheeled vehicle needs a bit of spring built in. The centre axle needs to be able to rise and fall a bit  so that any underlations can be ridden over.

It would certainly be interesting to see how much up and down movement those Roco ones have got. Presumably Hattons have possible got one of these in stock so they can examine it.

 

Andy G

[Compound2632]

9 minutes ago, Northroader said:

You have to be very good with your track laying to be sure that there aren’t any small changes in height over a long wheelbase vehicle, even more so when you get to point crossings.

 

The Cleminson or semi-Cleminson* set-up should give some degree of compensation, rather like a bogie carriage.

 

*Hereinafter "semiclemie".

[Allegheny1600]

25 minutes ago, uax6 said:

To some extent a 6 wheeled vehicle needs a bit of spring built in. The centre axle needs to be able to rise and fall a bit  so that any underlations can be ridden over.

It would certainly be interesting to see how much up and down movement those Roco ones have got. Presumably Hattons have possible got one of these in stock so they can examine it.

 

Andy G

If you really want, I can get the camera out again and show but a quick check shows that the "fixed" outer axles have about 0.5mm play or slop within the bearings, the centre axles appear to have a good 1mm vertical play or slop. Plus, there is a small amount of play in the sliding centre axle unit itself.

I'm sure I saw that Hattons do indeed have these in their 'pre-owned' range but happy to loan these to them if not.

Cheers,

John.

[adb968008]

3 hours ago, Wickham Green said:

The true Cleminson arrangement, I believe, simply pivoted the outer axles with no extra sideplay - but the arrangement adopted by Brassmasters with an intermediate pivot is more effective for model railways, for sure.

 

The other 'way round' the six-wheeler 'problem' would be an optional flangeless wheelset for those who need it ......... or, perhaps, an optional flanged wheelset for those who can accommodate it and might have more experience of swapping such things !!?!

Theres always the Rapido solution to the unsolvable problem...

Mould it on.

no one objected, indeed everyone cheered for it on the dynamometer car.. here hiding it would be even easier.

Edited October 18, 2019 by adb968008

[Tim Hall]

2 hours ago, melmerby said:

 

I bought one without knowing what compromises there were. (Note to self: do your research before buying!)

I ended up fixing the end axles and made sure the centre one could move side to side. Much better trackholding i.e it stayed on the track rather than taking to the shubbery at the slightest curve.

After all Hornby's long wheelbase CCTs work OK with a longer wheelbase and no silly swivelling.

The 12mm wheels however are unforgiveable. What where they thinking of?

Off-topic alert, apologies. Sold mine on eBay for a few quid more than I paid for it

[Northroader]

1 hour ago, Compound2632 said:

 

The Cleminson or semi-Cleminson* set-up should give some degree of compensation, rather like a bogie carriage.

 

*Hereinafter "semiclemie".

Agreed, what we were on about was a flangeless centre wheelset, which doesn’t have the same incentive to stay lined up with the rails. If you got it jacked up so it never touches the rails, you’re laughing, but it wouldn’t look very  attractive. If it’s running along the rails on the straight bits, alright, but on a bend??? That’s a nice spreadsheet you've got out.

[uax6]

I'm going to ask a daft question now:

 

Why not identify an area where there is a large amount of pre-grouping engines available and then produce a rake of accurate 4 and 6 wheelers to go behind those locos? I think that was the original intention looking at the fact that the original designs were obviously based on companies that made up the Southern Railway.

Get these really accurate, and paint them in the correct liveries and they WILL sell.

 

Then in a couple of years time select another suitable pre-grouping company (say those making up the LNER group) and do the same, and they will sell too.

 

And repeat.

 

This way eventually there will be good models of real coaches for some companies for which there are already locos, rather than something that will be neither fish nor foul for everyone.

 

Andy G

Edited October 18, 2019 by uax6