Oo couplings

[34theletterbetweenB&D]

On 22/10/2023 at 12:44, andyman7 said:

...It is more challenging to fit a CCM to a traditional short wheelbase UK 4 wheel wagon chassis - the examples noted above are (I think) all LWB or bogie modern freight stock. Has there been a 00 short wheelbase traditional wagon so-fitted?

For a camming type close coupling arrangement to function adequately requires a bogie pivotting in a vehicle frame on both the vehicles coupled. This arrangenment works well for bogie coaches and bogie wagons.

 

Rigid wheelbase vehicles, better not, and especially not as train weight increases: the drawbar load through the couplers tends to overcome the minimal force available to recentre the coupling mounting after curves. This is now being regularly demonstrated by the ill-advised fitting of such units to couple steam locos and tenders. The mechanism may well work with no load behind, but give it 60 wagons or a dozen coaches behind and the loco and tender maintain a skewed position relative to each other on exiting the first curve the train passes through.

[melmerby]

41 minutes ago, 34theletterbetweenB&D said:

But that doesn't mean it has to be mounted at Kadee's height specification. And having tried it out mounted higher than specification - joy unbounded! - it still works on Kadee's magnetic uncouplers; when first trying this I thought it might be necessary to straighten out the tails a little to obtain reliable magnetic uncoupling, but not so.

Which magnets?

I use the between rail magnets and they don't work well if the pin is not close enough.

[34theletterbetweenB&D]

 

2 minutes ago, melmerby said:

Which magnets?

Both Kadee's permanent magnet 'between the rails' and electromagnet under track type.

[The Johnster]

On 23/10/2023 at 10:27, BachelorBoy said:

Mind you, the lighting on this picture is all over the shop. The "white" light on the left is actually yellow, and the white light on the right is probably daylight. Not ideal for comparing colours.

 

This explains in part why discussions about colours are such a rabbit hole.  We are modellers, and one assumes that our intention is to have models that are as accurate to the form and appearance of the prototype as we can manage to our chosen scale.  Success in this endeavour depends on a degree of obsessiveness. 

 

As applied to dimensions (and remember we can't even get our track gauges right), this is simple enough in principle, if not always so in practice; you scale down the dimension recorded on the prototype and reproduce that dimension as closely as possible, where's the problem with that (don't start...).  But you can't do that so easily with colour, and liveries are of great significance in establishing not only detail but period.

 

Colour depends on far too many variables to be modelled by scaling it down:-

 

. It doesn't look the same on a small area as it does on a big one, so the side of a big diesel loco in 4mm tends to look darker to our senses as something about an inch by 10" than a real Peak, 8'x over 60.  Subjective perceptual issue.

 

. In reality the colour changes according to the ambient lighting conditions.  Weather-related of course, but the level of lighting is affected by atmospheric pollution, reflection from the surroundings especially the lower foreground, artificial backlighting including camera flash.  Rail Blue is a particularly hard one to pin  down, it could look almost green, purple, or grey depending on natural lighting on the same loco on the same day.

 

. In a colour film photo, the colour is affected by the camera settings, the film, and the ambient temperature, then further affected by the developing and printing process.

 

. The film then degrades subject to ambient temperatures and humidity.

 

. As does the print.

 

. In a digital photo, the colour is affected by the camera settings and the sensor.

 

. Film photos that have been digitised are further affected.

 

. Ok, all the images are digital now, so the problems are over, right?  Yeah, right.  The image now has to be reproduced on a monitor, and no two of those are the same even before we put our individual settings into the mix.

 

. Then we get the chance to post-edit, bringing up shadow, reducing/increasing exposure, contrast, tint, saturation. blah-de-blah.  This is not actually changing the image file, simply altering it's display to bring out features contained within the original data, and is usually 'corrective', but it is another stage away from the original exposure of reality.

 

.  And the monitor colour is affected by the ambient level and cast of the room, bus, train, aircraft, Iceni war chariot, or whatever we are in when we are looking at the image. 

 

. RTR manufacturers have the same problems when they are producing models as we do when we are looking at them or images of them.  They can match the colour on the model by referencing the original paint specification or matching a swatch to the real loco, but the scale perception problem still messes things up, never mind communication issues with the Chinese.  I'm always amazed that they get it as right as most of them do most of the time...

 

. Gloss, eggshell. or matt?  Cars are usually polished and shiny, go outside your house and look at some.  If they are more than about twenty feet away they look a bit matt, shininess is more apparent close up.  Twenty feet in 4mm is 8cm, couple of inches.  Gloss finishes look darker because they reflect more light and absorb less.

 

. Colour will fade in different and unpredictable ways under exposure to light over time.

 

. My ability to interpret and analyse any of the above may change over time and be radically different to yours.

 

 

That's fourteen variables, some of which are beyond any control, most of which are beyond my control, and none of which can be controlled or expressed in an objective quantifiable way.  Rabbit hole.

 

The top Peak is the correct version.  Discuss...

[markw]

6 hours ago, 34theletterbetweenB&D said:

For a camming type close coupling arrangement to function adequately requires a bogie pivotting in a vehicle frame on both the vehicles coupled. This arrangenment works well for bogie coaches and bogie wagons.

 

Rigid wheelbase vehicles, better not, and especially not as train weight increases: the drawbar load through the couplers tends to overcome the minimal force available to recentre the coupling mounting after curves. This is now being regularly demonstrated by the ill-advised fitting of such units to couple steam locos and tenders. The mechanism may well work with no load behind, but give it 60 wagons or a dozen coaches behind and the loco and tender maintain a skewed position relative to each other on exiting the first curve the train passes through.

If designed correctly the close coupling cam arrangement works fine with both bogies and rigid wheelbase wagons.

Both the Accurascale HAAs and Bachmann IPAs work perfectly with long heavy trains.

The spring is there to centre the coupling when it is not coupled and performs no function when coupled with a rigid coupling.

I have no experiance of the loco to tender couplings, sounds like poor implementation.

[adb968008]

All this about colour shade is good discussion, but the end state should be a standard….

so that way we have coaches and locos in a shade that matches, as a basic starting point.

 

Tbh I feel sorry for Br steam modellers… Hornby cant even get a consistent BR green on different models of the same class, let alone different models in Br green.. Ive a bunch of Bulleids, none of them match, but them try putting it next to a king, a castle or a grange…

 

BR had a standard, we should start there, and go by exception imo.

 

On couplings we have kind of adopted NEM, but do we know if the heights agree between manufacturers ?

Dapol are joining the butterfly nem pocket, but we really are seeing new innovation in this area, beyond the traditional hook/loop, but even the there is no standard and everyones doing their own style.

 

Edited October 24, 2023 by adb968008

[BachelorBoy]

7 hours ago, The Johnster said:

 

 

. My ability to interpret and analyse any of the above may change over time and be radically different to yours.

(I am not an ophthalmologist ... but this is roughly what one told me once. If there are any eye professionals here, please correct if necessary)

 

We become less sensitive to green light as our eyes age, so what we see is actually more orange/yellow, but our brains compensate so it doesn't seem that way. Colours appear less vivid, and our ability to distinguish between dark colours lessens.

 

Add to that the effects of ageing on memory, and the chances that a particular livery matches what you remember from your youth -- or think you remember -- reduce considerably.

 

Meanwhile, which locos are the correct colour in this photo? (Answer: they all are.)

 

 

[melmerby]

8 hours ago, adb968008 said:

Tbh I feel sorry for Br steam modellers… Hornby cant even get a consistent BR green on different models of the same class, let alone different models in Br green.. Ive a bunch of Bulleids, none of them match, but them try putting it next to a king, a castle or a grange…

 

BR had a standard, we should start there, and go by exception imo.

Except IMHO the BR Green seemed to vary anyway.

As I've said before, the BR Green on Kings and Castles always looked richer than that on Jubilees and Royal Scots

[34theletterbetweenB&D]

9 hours ago, adb968008 said:

On couplings we have kind of adopted NEM <coupler pockets> but do we know if the heights agree between manufacturers ?

As regards OO produced to date, the answer would be 'not consistently', it's a real mess. And it's not just height variation above rail top but several other key dimensions too, within the pocket, horizontality, outside face position relative to vehicle structure. Strangely the worst offender to date drawn from my experience  of nine current brand's offerings in RTR OO is Heljan; you might have thought that with a background in RTR HO they would be playing to a strength...

6 hours ago, BachelorBoy said:

the chances that a particular livery matches what you remember from your youth -- or think you remember -- reduce considerably.

Colour perception is fraught with difficulty. I am what was termed a 'divergent trichromat' in my youth, but now appears to be called 'anomalous trichromat'. I see the Sodium D lines as bright orange, these were defined as 'yellow' for the purposes of supplying the 'correct' answer in the Physics O level of the 1960s, no explanation available.

 

It wasn't until I got my hands on a university library that an explanation was found: there's a range of human colour perception, even with fully trichromatic colour sense, and unless an individual has been tested to determine that they conform very closely to the modal perception, you cannot trust their opinion. That starts with mine, I see Hornby's BR green as within the acceptable range, but I know why, and thus the reason why it will also be unacceptable for many.

[No Decorum]

17 hours ago, 34theletterbetweenB&amp;D said:

I use Kadee, and of course it is height sensitive in terms of identical position above rail top on each vehicle for maximum reliability. 

 

But that doesn't mean it has to be mounted at Kadee's height specification. And having tried it out mounted higher than specification - joy unbounded! - it still works on Kadee's magnetic uncouplers; when first trying this I thought it might be necessary to straighten out the tails a little to obtain reliable magnetic uncoupling, but not so.

 

Roco pattern, fixed link and  and magnetic couplers also work, it's no problem.

That's your opinion. Mine would be that it was a sensible adaption for use with OO, which Bachmann sadly failed to properly explain: and had they put the effort into communicating this, possibly there might have been greater design focus on consistent placement on their product.

We seem to have wandered OT into the realm of colour! Avoiding that, I have to agree very strongly with your last comment. The NEM pocket is an excellent idea but it’s in the wrong place. Bachmann’s idea was superb and it’s a bit of a shame it wasn’t taken further, for example with magnetic brake hoses which, I believe, have been produced in the USA. I still prefer tension lock for earlier times when a lot of shunting took place but for modern block trains, I fit the shortest Kadee coupling which will work. Tension locks are unsighlly and the old huge D types even more so but by abandoning the latter we have created a raft of new problems which complicated CCT mechanisms attempt to solve.

[adb968008]

Surely the obvious solution is a necklace chain cut to length, placed over drawbar hooks which are mounted on a spring loaded pivot for corners.

 

Now you could make the drawbar hooks magnetic, and the bufferbeam metal…,

 

so the hooks and chain are a single piece, and all you need to do is stick the drawbar hooks onto the right place on the bufferbeam and hey ho instant reality.

[markw]

2 hours ago, adb968008 said:

Surely the obvious solution is a necklace chain cut to length, placed over drawbar hooks which are mounted on a spring loaded pivot for corners.

 

Now you could make the drawbar hooks magnetic, and the bufferbeam metal…,

 

so the hooks and chain are a single piece, and all you need to do is stick the drawbar hooks onto the right place on the bufferbeam and hey ho instant reality.

Something like this ?

It needs a better way to make a representation of the three link coupling.

For vac braked stock I use a representation of the vac pipe hanging below the buffer beam which is easy to make from copper wire.

This is not a universal solution though. It is not usable if any shunting is required.

 

[adb968008]

6 hours ago, markw said:

Something like this ?

It needs a better way to make a representation of the three link coupling.

For vac braked stock I use a representation of the vac pipe hanging below the buffer beam which is easy to make from copper wire.

This is not a universal solution though. It is not usable if any shunting is required.

 

Yes along that lines…

now if the draw bar was on a pivot it could handle corners like conventional couplings. As well as be easy to fit and maintain as a chain.

 

i’m solutionising now.

[markw]

1 hour ago, adb968008 said:

Yes along that lines…

now if the draw bar was on a pivot it could handle corners like conventional couplings. As well as be easy to fit and maintain as a chain.

 

i’m solutionising now.

The round magnets behind the buffer beam and on the ends of the coupling create thier own pivot.

[melmerby]

Now if we could only get rid of the buffers..........😄

[34theletterbetweenB&D]

11 hours ago, melmerby said:

Now if we could only get rid of the buffers..........😄

In their current form, typically rigid. If the bufferheads were single pole magnetic (North left, South right)  with the shaft able to slide in the stocks, these could be the couplers. But with scale sized heads the curve limit would lie somewhere between 36" and 24" radius in 4mm.

[frobisher]

30 minutes ago, 34theletterbetweenB&amp;D said:

In their current form, typically rigid. If the bufferheads were single pole magnetic (North left, South right)  with the shaft able to slide in the stocks, these could be the couplers. But with scale sized heads the curve limit would lie somewhere between 36" and 24" radius in 4mm.

 

In theory, if you could clip a clear plastic shim across the face of both buffers you'd have something that might go down to set track radii.

[34theletterbetweenB&D]

1 minute ago, frobisher said:

 

In theory, if you could clip a clear plastic shim across the face of both buffers you'd have something that might go down to set track radii.

That's a version of 'the old way' with three or screw link couplers, usually a wire across the buffer faces. That was pretty reliable down to 24" radius.

 

Set track is a non starter because of the extreme reverse curve of the R2 substitution radius points arranged as a crossover.  That's the turd in the punchbowl of UK OO set track, it so needs a larger radius standard point that integrates into the geometry. It's perfectly possible, seen it done with Peco medium radius points; but it is typically too costly of space on layouts shorter than about 12 feet, to be generally acceptable.

[34theletterbetweenB&D]

On 24/10/2023 at 23:52, markw said:

If designed correctly the close coupling cam arrangement works fine with both bogies and rigid wheelbase wagons.

Both the Accurascale HAAs and Bachmann IPAs work perfectly with long heavy trains.

The spring is there to centre the coupling when it is not coupled and performs no function when coupled with a rigid coupling.

I have no experiance of the loco to tender couplings, sounds like poor implementation.

I have a selection of Accurascale 4 wheel coal wagons, of the 21T and 24.5T types and lovely models they are, and very neat coupled with rigid bar couplers of both the Roco and magnetic types. But they are mostly on 'restricted duties', essentially yard scenery, for the simple reason that they are not unconditionally reliable.

 

My expectation is that everything the prototype did, the models shall perform. In traction they nearly made it, but propelling across a point network are unreliable. My diagnosis was too much flex in the pillar between the cam and the pocket. The 21T examples selected for improvement are doing fine with a coupler pocket cemented in place, and now work as well as the Bachmann, kit and Hornby fleet. KISS.

 

As for the loco to tender camming couplings, apparently none of the designers at Bachmann, Hornby or Rapido (my sample set to date)  have grasped the intent of these mechanisms: on straight track the loco to tender spacing should be true scale, and on curves the cam action then proportionately increases the spacing such that the specified minimum radius can be negotiated. But no, they are spaced off overscale on straight track as though no camming mechanism was fitted, and then further disgrace themselves by failure to restore to straight alignment as they come off curves when trailing load exceeds a kilogram

 

Bachmann and Hornby coaches with camming coupler mechanisms perform as they should, but only if the owner fits an appropriate NEM specification coupler. The 'rigid bar' type couplers supplied with all the models I have purchased to date are overlong and space off the vehicles on straight track quite unnecessarily, in the same manner as the loco to tender couplers. Unfortunately with the latter there is no readily substituted alternative so butchery happens... The loco models it should be said are otherwise fine, and as is always the case with appearance, having the loco and tender ensemble correctly spaced further 'ices the cake'.

 

I have written to Bachmann regarding this aspect of their V2 model, and received a polite acknowledgement.

[sparaxis]

Strangely enough, the major European manufacturers (including the Hornby subsidiaries) have got close coupling mechanisms well sorted out. Many steam locos have effective loco-tender mechanisms too. Coupler pockets of both types are to specification, including the little swallowtail NEM 363 that is intended to be mounted on a kinematic mechanism. The standard UK implementation where the NEM 363 is mounted at a non-standard location and a bendy NEM 362 is mounted in it is just bizarre. As for wagon size being a "problem", some of the Trix 19th century wagons are tiny (eg Trix 24099). Ironically, Bachmann in their Liliput brand makes a very nice close coupling, which is basically a mini-tension lock with guiding horns to make it "rigid" (Liliput L939105) . How do I know this? With well over a 1000 pieces of rolling stock, there are very few that have problems, and those are typically where the designer has deviated from proven practice.

 

As far as UK outline is concerned, within passenger rakes, I use a variety of European couplings, depending on what works best in the circumstances. For goods wagons, I have given up and I remove the NEM mounts and install long-shank Kadees as the NEM mount ones are both ugly and expensive.

[melmerby]

54 minutes ago, sparaxis said:

As far as UK outline is concerned, within passenger rakes, I use a variety of European couplings, depending on what works best in the circumstances. For goods wagons, I have given up and I remove the NEM mounts and install long-shank Kadees as the NEM mount ones are both ugly and expensive.

I use #146 on UK 4 wheel wagons, mounted on the underside of the floor, it gives the correct height for the Kadee gauge and is long enough for buffers not to touch.(and lock on reverse curves)

Passenger vehicles with kinematic mount get Roco close couplers. (Kadee are useless on these.)

[melmerby]

Just now, melmerby said:

the NEM mount ones are both ugly and expensive.

They used to be about the same price as #146 with gearbox but are a lot more now.

[frobisher]

On 26/10/2023 at 11:43, 34theletterbetweenB&amp;D said:

That's the turd in the punchbowl of UK OO set track, it so needs a larger radius standard point that integrates into the geometry.

 

Erm the Express Point surely does this?

[34theletterbetweenB&D]

Folowing some experimentation, everything 4 or 6 wheeled brake fitted will have magnetic coupling, or Roco type where there is effective kinematic provision, which in the RTR OO I have means bogie vehicles, with end of train vehicles having Kadee on the outer end, mounted in the bufferbeam.

 

Unfitted wagons, Bachmann miniature tension lock as it provides a reliable loose coupling effect. (Convertor wagons with a Kadee to enable Kadee fitted locos to operate loose coupled trains.)

 

(Kadee for loco to train coupling selected because it works, and all LNER and BR gangwayed had it fitted so it looks appropriate.)

4 minutes ago, frobisher said:

Erm the Express Point surely does this?

I would have hoped so, but have been told (quite forcefully, some time in the past) that it doesn't integrate properly into the set track geometry. Whether this is correct I neither know nor care, but if somone who has used this item can comment one way or the other, it might be useful to others?

[sparaxis]

1 hour ago, melmerby said:

They used to be about the same price as #146 with gearbox but are a lot more now.

I buy the #156 in bulk packs, "scale size" they are a little neater than the #146. But they work great considering that a loose coupled train should be about 3mm between buffers when in tension.