Hod Carrier

That’s lucky. I guess your build doesn’t include any of the parts where LDD fails to agree completely with Bricklink. As well as modifying your build to suit Bricklink, be aware that you can also look for alternative parts within the Bricklink catalogue. There are often minor variations in design, but LDD doesn’t differentiate between different versions of the same part (e.g. 1x2 tile with or without grooves). Also, some parts have more than one part number, sometimes because of a part being reissued or having some minor internal redesign. By exploring these differences in the catalogue you can sometimes find an alternative part which looks the same but in greater quantities and, therefore, at a lower price. Basically, I use LDD as a design tool and a way of compiling a parts list, but I rarely stick faithfully to this list when making Bricklink orders.

It’s supposed to but I’ve never found it to work. If there is any single brick in your build that is not correctly described in terms of it’s shape, colour or part number, or if a part you have used does not actually exist, it will throw the whole list out. You may say that this should not happen given that LDD is the official software released by TLG themselves, but it’s all too common in my experience. If you want to try I believe that Bricklink gives you the option to upload to the website rather than it being an option within LDD. It’s so long ago that I last tried it that I can’t honestly remember all the details.

Nope. I think you’re going through the same process I went through. The more I visualise, design and build the less I wish to buy TLG’s official offerings. Surely the whole point of LEGO is that you can build whatever your mind can imagine.

I'm not really a set builder, but I did pick up the Mustang, Fiesta WRC and Porsche 919 at the weekend from my local supermarket. I'd been toying with the idea of getting involved with the Speed Champs theme for a while but nothing had tickled my fancy before. I have to say that the Mustang is my new favourite thing. It looks cool and the colours are great, and I even applied the stickers (got to love those gold stripes on green and black). Given the limitations imposed by using LEGO bricks I think they've done a great job of capturing the shapes of the original. If anything some of the details, like the tail lights, could have ended up as a sticker, but they've actually bothered to design them to be built in brick!! I'm not at all disappointed with it. All three sets were satisfying to build, and I guess it's unavoidable that racing cars will require a whole load of stickers. But taking my time to ensure that they were all correctly positioned paid dividends and all three models look very sharp. If I had to make any criticism it would be that the proportions of the Fiesta are wrong, but apart from that the essence of the car is still there. Will I be buying more Speed Champs sets...? Quite probably.

I take my inspirations from what I see around me rather than from specific builders or models. Working on the railways gives me plenty of exposure to lots of interesting prototypes as well as an understanding of function as well as form. I often look at different things and wonder how I might make them in LEGO. Many of my ideas fail to get beyond the thinking stage, but some ideas show more promise than others. Apologies if this is not in keeping with the ethos of this thread.

Another intriguing solution from outside the box. You clearly have a very fertile imagination.

Sounds like you've found a good combination of parts to make it work so well. That's excellent!! And yes, I can confirm that your lamp code is correct.

Oh, now that is rather nice. Even though the proportions do look wrong, the early tinplate Hornby locos did have that slightly tall and ungainly appearance that you've recreated very well. I'm pleased that the performance has improved too. What do you think made the difference? Was it the basic flywheel, the BBB Wheels or something else?

What options do you have to re-scale the bogies? If you could make them shorter it would give you more space for a larger fuel tank. Sometimes the answer is not to scale things correctly but to apply correct proportions.

Lovely little engine. I do like that very much. Ultimately weight helps traction, so having a tiny little loco without any onboard power or control features does limit how much adhesion you're going to get. To get the best out of the 4-wide scale TRAXX loco I built I needed the weight of the loco plus that of the PP3 battery, SBrick and even a 2x6x2 weight brick to make it run properly. A few initial thoughts occur to me. I'm wondering if a chassis redesign might help to get more from your loco. Powering both axles might help with power transmission and reducing the wheelbase from 7 to 5 studs might help reduce any friction you're suffering in the curves. I also found with my TRAXX that the LEGO traction bands are appalling, so I swapped them for rubber O-rings of equivalent size and there was much less wheelspin as a consequence. What's the problem with power pick-up? Are the pick-ups themselves not staying in contact with the rails or is it something else? If it's a question of contact, you really need to try and get them as close to the line of the axles as you can. Short of making the wheels conductive (which would remove the option to use traction bands), I can't immediately see another way. Maybe you need to think outside the box a bit. How about overhead collection using a pantograph or trolley pole with common return through the track? BTW, are my eyes deceiving me or is that wagon self-steering? It looks fairly long and might be a significant source of friction.

You beat me to it!! The bigger the curve radius the happier these vehicles will be. The trick is to tailor the amount of axle articulation to suit the smallest radius that they are likely to encounter; so the bigger the radius the less articulation you will need. Eventually, as @Paperinik77pk says, you will get to a radius big enough that the axles don't need to articulate at all and can be fixed.

A very clever idea, but not a new one. Some of the earliest ideas for radio waves was to use them to create a wireless power network to send electrical power over long distances. Although this may not necessarily affect LEGO trains, I’m not keen on constantly charging. If I understand correctly, the life of a lipo is affected by the number of charging cycles it is subjected to. Therefore using this could potentially shorten the life of a device.

This is where your three axle design has the advantage over the two axle designs. Because all three of your axles influence and steer each other, the centre axle is centring the two outer axles and reducing the deflection which is the source of the unwanted friction. With a passive steering two axle design the axle at the blue end of the vehicle would still be turning hard left against the direction of the curve because the axle of the red end would be turning into the curve under the action of the coupling to the neighbouring car.

@moustic Yes I tried it but it doesn't work. The problem is that the length of the car is so great that a fixed axle at one end is not actually following the curve but trying to drive across it. This turns the wheels against the inside of the rails and the friction this generates is enormous. @Ludo I have removed the steering link between the axles. I thought the steering link was a good idea when I was testing the prototypes, but I now think the vans works better without it. As @LEGO Train 12 Volts said, the steering link sometimes turns the wheels the wrong way at the wrong time and I discovered it can cause more problems when running heavy vans like the VGAs. The vans do need the extra regular wagon at the end to control the last axle, though. Add the elastic bands to the magnets too and these wagons will now run anywhere on any track, forwards or backwards.

I think I've reached the end of the developmental line too and hit the bufferstops. While it wasn't possible to hit all the targets I had set for myself I still feel happy with the progress made. Maybe someone brighter than me will come along and solve the free axle problem. In the meantime, I shall be making sure that my VGAs are coupled at both ends.

Ooo, I don’t know. As a majority 4-wide modeller I would love a good chat about narrow gauge. But then I can’t get to Chicago in June, so perhaps I don’t get much of a say.

I like it. I’m not sure you’re going to get the shape of the nose much closer to the real train than you already have. With regard to the bogies, perhaps you need to build the bodysides down towards the track and maybe fit some skirts to the bogies to hide them a bit.

I thought about this too but abandoned the idea because I couldn't see how to make it work reliably. It would be fine if the axles lined up properly as they should so that they could engage with each pivot in turn, but they don't always. At this point perhaps we might have a little recap because the thread is starting to get quite long and there are lots of ideas contained within it, some that have been tried and tested and some that have not. I think we have established that long wheelbase cars are possible and that there are various techniques you can use to make this happen. The consensus seems to be that independent axles are better than those rigidly linked and that self-centring couplers are necessary if you want to push these cars without excessive friction due to "bunching". Where axles are coupled to a neighbouring car the vehicle is happy to go anywhere, forwards or backwards, and even through standard points. The issue still to be resolved is how to control a free axle that is not coupled to another car, especially when pushing the train. @Paperinik77pk, would you agree that this is the current situation?

Some very interesting thoughts. I look forward to seeing the results of your research in action. The problem that causes "bunching" on straights is to do with a hinged lever's natural tendency to try and shorten itself when under compression. The forces acting on the coupling to push it out of line only need to be very slightly away from perpendicular to the axles to cause the coupling mechanism to fold up and cause "bunching". Most often just coming out of a bend onto a straight provides enough deflection for "bunching" to take over because the axles are turned. To overcome this there needs to be a way to impose a straight line on the entire mechanism either through a) centring the axles or b) centring the couplers. Personally I favour option b because any force that is acting on the axle to centre it must be overcome in order to induce it to self-steer. Another possibility might be to try and find a geometry whereby the length of the entire mechanism between the magnetic coupler and the axle assembly pivot is shortest when it's in it's central position. You're absolutely correct to say that the size of the force will be proportional to the length of the lever, but it will also be proportional to the mass of the object being pushed and the resistance due to friction. I've not weighed the VGAs yet but, at over 700 parts each, I expect they will be pretty close to 1kg. That's quite a lot of weight to push. Add in the friction from the axles themselves and the forces acting through the couplers under compression will be quite high. I'm beginning to be persuaded that a passive steering link might not be entirely helpful. I put the links back on the VGAs and suddenly I was in a world of problems with derailments and other issues. It might be because of the modification to the couplers, but I'm still trying to understand why the cars now behave this way. In addition to this, I do agree with @LEGO Train 12 Volts regarding the need for axles to be fully independent. When you start getting out to very long wheelbases it's very likely that the passive steering will cause the axles to be turned in the wrong direction at the wrong time, as is the case with my cars when I try pushing them through points. Hopefully you will be able to come up with a better solution than mine that eliminates this problem. I think I may have misunderstood something you said earlier about the behaviour of your cars. Did you say that the wheels are steering in the opposite direction when being pushed through curves? Is that still happening?

I was idly watching the VGAs going round and round on my kitchen floor earlier today, seeing that taunting Z shape made by the axles and couplers as they failed to centre properly, and wondering what it was that I might have missed. Then it dawned on me. I'd spent so much time concentrating on the axle pivots that I'd completely forgotten that there was another set of pivots at play; the ones on the magnetic couplers. What would happen if I could make them self-centre, and what effect might that have on the behaviour of the axles? Well, click on the image below and see.

Interesting stuff. You’re right about “dumb” and “smart” axles. It’s an analogy I’ve used too. The challenge is working out how each axle “knows” which way to articulate at any particular moment. Sadly I’m at work at the moment so I can’t share a little discovery I made earlier today until much later tonight, but it’s something that seems to help. I’m wondering if maybe we’ve both had the same idea.

That's very kind. Thank you. I wasn't consciously going for a studless look, but it just seems to have turned out that way. There are some exposed studs on the chassis, but only a very few. Most kind. May I have a chocolate chip...?

Oh, I see. So there are still issues even with this set-up. I can see how the stop pins will prevent the axles wandering off in their own direction, but I can also see how much they restrict the amount of articulation. The way the wheels are scrubbing against the rails in that last photo looks painful. If you had a heavier car the friction that would generate could stop the train dead in it's tracks. It's also interesting to see where you've decided to put the axle assembly pivot point. You've given me some things to think about and try out.

That’s an interesting concept. I’d like to build and test it too and see how it works out, if that’s OK.

I've carried out a few tests off camera. I hope no-one minds there not being a video but time is tight at present. If there's demand I may find time on another day to do some filming. I modified the VGAs to have elastic bands for centring and removed the passive steering mechanism. Being a Sunday and having been at work it was only done with table scraps, but I followed the principles laid down by @LEGO Train 12 Volts. Rather than a single band I used a pair of thin bands on each axle assembly (actually each band was a pair of "loom bands" linked together to give the necessary length). Running both vans together the behaviour of the coupled axles was little different to how they would behave if the axles were free castering. The self-steering was near identical and the axles centred as they would without assistance. In light of this observation I removed the elastic band centring from the lead VGA and continued the test. This was when I noticed that the self-steering was less on the van with elastic bands compared to the van without. Even halving the centring force applied to the axles by removing one of the pair of bands did not noticeably improve the level of articulation compared to the free castering axles. This reduction in articulation did result in an increase in friction between the wheels and rails. Even while running forwards the train slowed marginally, although noticeably, when going through bends. Where things were different was with the last axle. As @LEGO Train 12 Volts predicted this axle stays pretty well centred but, as I feared, this was mostly because it didn't seem to articulate very much at all. About the only time it seemed to move dramatically was when the wheel caught one of the check rails on the points when being pushed through. There seems not to be any force acting on it to induce a steering effect strong enough to overcome both the friction in the pivot or the centring force exerted by the elastic bands. On the plus side, it did at least keep the axle sufficiently centred to prevent the wheels steering themselves through the gap in the frog when being pushed through points at low speed, although the train did stall due to friction and even derailed a couple of times further through the points. I then tried @zephyr1934's idea of removing the pivot altogether from the rear axle, but sadly the wheels scrubbed so badly that the friction was simply disastrous. I'm beginning to wonder if there are any simple answers to this conundrum. My initial thought was to try and find some way to make long wheelbase cars viable without having to worry about having lots of different systems requiring operators to know where in the train they should go or which way round they should run or what types of track or track formations to avoid. However, I now think that this was perhaps too ambitious. I appreciate that I'm probably pushing things quite far with a 24 stud wheelbase, but then if a system works it should work for the longest of cars as well as the shortest. The idea of having each axle independently steered, as @zephyr1934 suggests, is obviously a good one. But how can it be implemented? How does an axle know which way it should be pointing without reference to some external factor? Those axles that are coupled act under the influence of each other, but the last axle is a problem because it is not coupled to another axle. Perhaps the simple answer is to stick with free castering axles, but don't try pushing these long cars through any R40 points unless you have a conventional non-castering car to keep the last axle under control. Oh, and make sure you use a BIG loco to overcome the friction due to "bunching" if you ever need to push them. Discuss.