mxp

awesome, I think you're right, it's a whip. Thank you all so much!!!

Hi community, I found that great graveyard on flickr (https://www.flickr.com/photos/vitreolum/20920542846/in/pool-lego/) that contains a brown hose/tube-like part (see image). Despite extensive search I don't seem to be able to identify that part. Does anyone know what part number that is or if it's even original Lego? Thanks for your help! Sebastian

Thanks @suffocation I will try 1:9 and see how that works. I could post some pictures once I'm done, but that might take a while

Thank you everybody for your feedback, I really appreciate it. There seems to be a consensus here what I should do: So I will go with hard coupled motors that are directly connected to the sprockets. @suffocation Thank you for your advice and even trying it out. That's seems to be what I will be needing (also from what others said) @Saberwing40k Why would I be offended? Thank you so much for your feedback and advice. So unfortunately, I can't reduce the model's size. It's probably not what you were thinking of and in most people's opinion here probably not a great build, but since you asked, here is a video. What I'm trying to do is to put the following on to wheels/treads: It's WIP and I'm still working on some details. It weighs (including the base that will be removed later) 8.8kg. I assume that with a structure that can drive it, it will come out somewhere around 12-15kg. @Sariel Wow, thanks for your answer. I actually read your book and watch your workshop reports on youtube every month. So thanks for taking the time and helping me. I was actually afraid of the bevel gears breaking, that's why I wanted to gear up a lot. But from what you and other people are saying here that doesn't seem to work. So I will go with connecting the motors directly to the sprockets and hard coupling multiple of them. @Doug72 Thanks for your suggestion Doug. I think your idea would work. The only problem is, that because I need to couple so many motors to get enough torque to move 12kg that I would need a lot of those differentials. Since it is quiet big, the model would become even heavier and bigger. It's a good idea but I think in my specific case, I will go with the simpler design. Again, thank you everybody for your feedback. It was very helpful and I really appreciate it.

I would use a combination of an 8 tooth gear and a 24 tooth gear twice, giving me a ratio of 1:9. Do you think I would need even more gearing up? The batteries shouldn't be an issue, I'm not using the lego battery box but will build my own, using AA or LiPo batteries. The lego battery box is just too limited.

Hi Everyone, I have a pretty heavy model that I would like to put on treads. The final model will probably weigh something around 12-15kg. The model is also supposed to move at a certain speed (around 10cm per second). As a result I think I will need to combine several PF XL motors to get the necessary torque and speed. In my opinion I have 2 options: Option 1: Adders + Subtractor I would connect several PF XL motors via adders for torque and then a subtractor for steering. I think I would need to heavily (9:1) gear up each motor before the differentials because the small 12 tooth bevel gears in the differentials (for adders and subtractor) don't handle torque very well. So I would first gear up and then, behind the subtractor gear down, so that I get more torque again. Advantage: Model can go straight (thanks to the subtractor); No hard-coupling (motors won't suffer) Disadvantage: A lot of power from the motors gets lost because there are so many gears. I'm not sure how fast lego gears and axles can spin for a long time without breaking (PF XL motor 200rpm with 9:1 gear up = 1800rpm) Option 2: Several PF XL motors on each tread I would have multiple sprocket wheals for each tread that is driven by a PF XL motor. Advantage: Simpler construction; less power loss Disadvantage: Hard-coupled motors (coupled through the tread links); model never goes straight because all motors won't turn at exactly the same speed. My question is, do any of you have experience with very heavy treaded models? What's the best way to drive them? (so that they can go straight) How many PF XL motors would I roughly need for a 12-15kg model? Thanks for your help and let me know if my description of the problem doesn't make sense :)