ozacek

I was suspecting something like that, but I'm surprised it's 'massive'. Do you think it comes from just having more gears, or from something else?

That's a really good idea, I like that! It's clean, simple, and certainly enough for my needs.

Then still about axle twisting, if I need to transmit high torque over a fairly long distance, say 16L, one 16L axle or two 8L is probably not the best choice, but it there some rule of thumb? Should I go all the way down to 2L and just have a series or axle connectors, or something in-between? Thank you.

Thank you for the insight. Though by weaker, I meant that it's more prone to twisting under high torque. It's much easier to twist an 11L axle than a 5L one. Edit: I see what you mean, the twisting only applies over the length between where the gears transmit the torque, which is indeed the same. I hadn't thought about it this way - thanks!

There's something about which I can't quite make up my mind, and I was wondering if others have an opinion. In a case like this, where a lot of torque goes through (like lifting up a heavy vehicle), is there a preferable approach? In the top setup, the axle has better support, but it's weaker because it's 9L long. In the bottom setup, it's the opposite. Also, if you think the top setup is better, would that still be the case if the axle had to be 11L ? Thanks!

I completed the model and made instructions, in case anyone is interested. https://rebrickable.com/mocs/MOC-37412/olivierz/crawler-crane-42097-with-motorized-legs

I made a mod to have all outriggers deploy, lower & extend with a single motor, i.e. replacing 12 manual gears:

The 42054 is somewhat old news, but with this year's 42102 refresh, I thought it was a good time to go back to my previous attempt of adding RC steering & drive. More than one of this mod already exists, but I had different goals. While the existing mods tend to heavily modify the internal structure, I wanted to preserve it, and most importantly, keep intact the steering mode selection mechanism & cabin rotation mechanism, which I personally find to be among the best of any technic set. I also wanted to preserve the side-panel switches. The entire mod use very few extra parts, probably less than 100. I do not plan to make instructions, as I'm using MLCad and its single-threaded software renderer makes it unusable on models above ~1000 parts. But I'm uploading a bunch of pictures, for those interested, or to give potential ideas to other modders. Summary of changes: Removed inner gearing that controls tool shaft & cabin rotation, to make space for a servo-motor that replaces manual steering. the M-motor is moved up to the cabin, in place of the manual steering mechanism. There's also a clutch gear now (the original design uses two clutch gears for the tool shaft and none for the cabin - it seems like a mistake) XL-motor takes the place of the M-motor, feeding into a 2-speed LO/HI gearbox, then to all wheels (4x4). Both axles now have differentials. Battery box moved out as a tool-attachment, to the back in order to balance the overall weight. Otherwise there is much too much weight in the front. IR-receiver takes the place of the battery box, under the hood, poping out where black stripes used to be, making it nearly invisible. One of the side panel's switches still control the cabin rotation, while the other controls the LO/HI gear switching. Drawbacks: I've only decided to add a gearbox later on, and there wasn't enough horizontal space left to secure one end, it's only supported vertically by other gears. Because of that, there's gear clicking when the tractor starts to move. the rear tool shaft is gone, and the front one is coupled to the drive, i.e. it only functions when driving. the original cabin rotation uses a heafty 25:1 speed reduction, which I couldn't achieve in such little space up in the cabin, so it's 2.8 time too fast.

Where is the right place to continue this discussion then? (or is there no place at all on this forum?)

For anyone interested, out of curiosity, I've tried building one technic set of most of the brands that make technic sets. I'd rate the manufacturing quality of the parts as follows, Lego being 10/10: - Mould King 9/10 - Sembo 8.5/10 - Cada 7/10 - Lepin 5/10 - Winner 4.5/10 Anything 5/10 or less isn't good enough for moving parts to work properly. Note that I'm only talking about the quality itself - most of them chose to have much tighter pin & axle connection, which I personally really don't like, but I guess that's a design choice. For the PF system, I'd say Mould King beats Lego hands down. (sorry in case all this it too off-topic)

Actually I just finished building a CADA set out of curiosity, and just about every part down to the pins is distinguishable from Lego.

I also tried chrome tracks, but it doesn't look as good as I had hoped. Actually it even looks a bit weird, like they're wrapped in aluminium foil. Too bad, because those were real expensive :)

That's great!! Personally I find that's one of the most desirable feature of a big car, and one most often missing.

What happened with this project, is it off? It was looking very promising..

Sorry for reviving this old post, but I stumbled upon it while looking for something else. Then I thought I had to add my 2 cents. I have to say, the greatest mechanism I have ever seen is the one behind Akiyuki's Catch & Spin Robots. If you see it in action knowing that there are no sensors, just gears, then your first thought is "impossible".