Congratulations on effectively modelling two completely different trains, at a very high level of detail, and with some great technical solutions, and all in a short timeframe. A hard earned and well deserved win!

Sorry for bringing this back up from the depths, but I wanted to post an update.

As I mentioned during the building phase of the project, I was not entirely satisfied with the close coupling system I had employed for this build as it wasn't very well optimised for an articulated train. Part of the problem was that the geometry did not automatically centre the cars which meant that found myself having to resort to using strong elastic bands to achieve this, plus it did not fully separate the articulation of the cars from the rotation of the bogies. It was an OK solution but not ideal as it caused a few unwanted side-effects, such as causing the fully-articulated middle car to lean alarmingly outwards on any curves due to the change in the weight distribution as a consequence of the pivot point shifting with the articulation. It also needed a very strong pull to achieve any centreing.

After a good long break from the build I decided that I needed to revisit the design and address these problems and try to come up with something a bit better. And here is the fruit of my labours.

The innovation is the diagonal linkage (coloured red). This provides the force to centre the cars and also acts to stabilise the middle car to prevent it from leaning. It has necessitated a bit of a redesign inside the railcar to accommodate all the changes, but these alterations now allow for the coupling gap to be shortened if necessary for larger radius curves. I have also altered the design of the central member (coloured white) to make it more compact.

The results are just as I had hoped. The cars now articulate independently of the bogies and the middle car is now stabilised. It can still negotiate R40 radius curves and handles points/switches with ease. Here's a couple of very short videos of it in action.

Edited June 19, 20231 yr by Hod Carrier
Fixed video link

Well done! Impressive how well it works with the long cars and tight curves.

Dave

@bogieman Thanks Dave. 

That's some crazy black magic you are messing with there. I still can't completely wrap my head around all of the dynamics (and no, I'm not asking you to try to explain it using small words, ignorance is bliss, as they say).

Just one thought, could the red axle in your schematic pull apart? I assume you are not using a technic beam because the spacing is not an integer number of studs, no? If so, I'd suggest a bit of cragle

On 6/19/2023 at 9:20 AM, Hod Carrier said:

 

20 hours ago, zephyr1934 said:

That's some crazy black magic you are messing with there. I still can't completely wrap my head around all of the dynamics (and no, I'm not asking you to try to explain it using small words, ignorance is bliss, as they say).

It's geometry Jim, but not as we know it. 

20 hours ago, zephyr1934 said:

Just one thought, could the red axle in your schematic pull apart?

It's possible. Perhaps I'm a little less squeamish than some, but I'm happy to glue these parts to prevent that from happening.

20 hours ago, zephyr1934 said:

I assume you are not using a technic beam because the spacing is not an integer number of studs, no? If so, I'd suggest a bit of cragle

That's right. I'd happily take a suggestion. 

how long is that cross axle? i might have a solution depending on how long that is.

you can make it longer or shorter by varying the length of the tile or by adding plates between the technic bricks and the brackets. for a slimer solution you have to make the brackets go over the technic bricks holes. it should have more strenght in tension for shure.

 

Edited June 25, 20231 yr by XG BC

@XG BC That's a great idea for an adjustable link, but unfortunately it's a bit too bulky to work in the railcar. I really need the link to end with pin connectors otherwise there won't be enough space for it to articulate.

On 6/25/2023 at 7:23 AM, Hod Carrier said:

On 6/24/2023 at 11:06 AM, zephyr1934 said:

I assume you are not using a technic beam because the spacing is not an integer number of studs, no? If so, I'd suggest a bit of cragle

That's right. I'd happily take a suggestion. 

You hadn't said why the technic axle or that you were using glue, so my surmising was correct. These are important points for someone who is attempting to replicate (I say as someone who finds this design enticing). You expanded on that in the other thread. Glue is as good as anything else in this situation for the non-purist. One could also 3D print a link of exactly the right length but it would probably be more expensive.

Great work

3 hours ago, Hod Carrier said:

@XG BC That's a great idea for an adjustable link, but unfortunately it's a bit too bulky to work in the railcar. I really need the link to end with pin connectors otherwise there won't be enough space for it to articulate.

fair enough.

On 6/25/2023 at 1:23 PM, Hod Carrier said:

but I'm happy to glue these parts

Same here

What I sometimes do is drilling a hole (e.g. 1 mm diameter or less) through the carefully adjusted pieces (here Technic axle and Technic axle connector) and then locking them into place with a 1 mm dia (or less) short piece of wire bent at both ends, so it does not slip out.

Best,
Thorsten   

On 6/27/2023 at 4:45 PM, zephyr1934 said:

You hadn't said why the technic axle or that you were using glue, so my surmising was correct. These are important points for someone who is attempting to replicate (I say as someone who finds this design enticing). You expanded on that in the other thread.

That's kind of why I started the close-coupling round up thread, so that information and discussion could be focused there rather than being scattered around in different threads. It's easier for anyone who stumbles upon the idea and wants to copy it to find all the information in one place rather than having to search for it in different threads where it really is only a side-topic.

I am happy to signpost readers to different parts of other threads if that is considered helpful, but really I'd rather it be done from the thread specifically relating to the topic to show examples where it has been applied.